JSONObject.java

package org.json;

import java.io.Closeable;

/*
 Copyright (c) 2002 JSON.org

 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
 in the Software without restriction, including without limitation the rights
 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 copies of the Software, and to permit persons to whom the Software is
 furnished to do so, subject to the following conditions:

 The above copyright notice and this permission notice shall be included in all
 copies or substantial portions of the Software.

 The Software shall be used for Good, not Evil.

 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 */

import java.io.IOException;
import java.io.StringWriter;
import java.io.Writer;
import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.Collection;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Locale;
import java.util.Map;
import java.util.Map.Entry;
import java.util.ResourceBundle;
import java.util.Set;
import java.util.regex.Pattern;

/**
 * A JSONObject is an unordered collection of name/value pairs. Its external
 * form is a string wrapped in curly braces with colons between the names and
 * values, and commas between the values and names. The internal form is an
 * object having <code>get</code> and <code>opt</code> methods for accessing
 * the values by name, and <code>put</code> methods for adding or replacing
 * values by name. The values can be any of these types: <code>Boolean</code>,
 * <code>JSONArray</code>, <code>JSONObject</code>, <code>Number</code>,
 * <code>String</code>, or the <code>JSONObject.NULL</code> object. A
 * JSONObject constructor can be used to convert an external form JSON text
 * into an internal form whose values can be retrieved with the
 * <code>get</code> and <code>opt</code> methods, or to convert values into a
 * JSON text using the <code>put</code> and <code>toString</code> methods. A
 * <code>get</code> method returns a value if one can be found, and throws an
 * exception if one cannot be found. An <code>opt</code> method returns a
 * default value instead of throwing an exception, and so is useful for
 * obtaining optional values.
 * <p>
 * The generic <code>get()</code> and <code>opt()</code> methods return an
 * object, which you can cast or query for type. There are also typed
 * <code>get</code> and <code>opt</code> methods that do type checking and type
 * coercion for you. The opt methods differ from the get methods in that they
 * do not throw. Instead, they return a specified value, such as null.
 * <p>
 * The <code>put</code> methods add or replace values in an object. For
 * example,
 *
 * <pre>
 * myString = new JSONObject()
 *         .put(&quot;JSON&quot;, &quot;Hello, World!&quot;).toString();
 * </pre>
 *
 * produces the string <code>{"JSON": "Hello, World"}</code>.
 * <p>
 * The texts produced by the <code>toString</code> methods strictly conform to
 * the JSON syntax rules. The constructors are more forgiving in the texts they
 * will accept:
 * <ul>
 * <li>An extra <code>,</code>&nbsp;<small>(comma)</small> may appear just
 * before the closing brace.</li>
 * <li>Strings may be quoted with <code>'</code>&nbsp;<small>(single
 * quote)</small>.</li>
 * <li>Strings do not need to be quoted at all if they do not begin with a
 * quote or single quote, and if they do not contain leading or trailing
 * spaces, and if they do not contain any of these characters:
 * <code>{ } [ ] / \ : , #</code> and if they do not look like numbers and
 * if they are not the reserved words <code>true</code>, <code>false</code>,
 * or <code>null</code>.</li>
 * </ul>
 *
 * @author JSON.org, modified by Immo Schulz-Gerlach
 * @version 2019-07-01
 */
public class JSONObject {
    /**
     * JSONObject.NULL is equivalent to the value that JavaScript calls null,
     * whilst Java's null is equivalent to the value that JavaScript calls
     * undefined.
     */
    private static final class Null {

        /**
         * There is only intended to be a single instance of the NULL object,
         * so the clone method returns itself.
         *
         * @return NULL.
         */
        @Override
        protected final Object clone() {
            return this;
        }

        /**
         * A Null object is equal to the null value and to itself.
         *
         * @param object
         *            An object to test for nullness.
         * @return true if the object parameter is the JSONObject.NULL object or
         *         null.
         */
        @Override
        public boolean equals(Object object) {
            return object == null || object == this;
        }
        /**
         * A Null object is equal to the null value and to itself.
         *
         * @return always returns 0.
         */
        @Override
        public int hashCode() {
            return 0;
        }

        /**
         * Get the "null" string value.
         *
         * @return The string "null".
         */
        @Override
        public String toString() {
            return "null";
        }
    }
    
    /**
     *  Regular Expression Pattern that matches JSON Numbers. This is primarily used for
     *  output to guarantee that we are always writing valid JSON. 
     */
    static final Pattern NUMBER_PATTERN = Pattern.compile("-?(?:0|[1-9]\\d*)(?:\\.\\d+)?(?:[eE][+-]?\\d+)?");

    /**
     * The map where the JSONObject's properties are kept.
     */
    private final Map<String, Object> map;

    /**
     * It is sometimes more convenient and less ambiguous to have a
     * <code>NULL</code> object than to use Java's <code>null</code> value.
     * <code>JSONObject.NULL.equals(null)</code> returns <code>true</code>.
     * <code>JSONObject.NULL.toString()</code> returns <code>"null"</code>.
     */
    public static final Object NULL = new Null();

    /**
     * Construct an empty JSONObject.
     */
    public JSONObject() {
        // HashMap is used on purpose to ensure that elements are unordered by 
        // the specification.
        // JSON tends to be a portable transfer format to allows the container 
        // implementations to rearrange their items for a faster element 
        // retrieval based on associative access.
        // Therefore, an implementation mustn't rely on the order of the item.
        this.map = new HashMap<String, Object>();
    }
    
    /**
     * Construct an emtpy JSONObject with a user-defined factory function for the object's property map.
     * The caller can choose the map implementation by passing a map supplier which should always create a new, empty map. 
     * This may be used especially to influence the iteration order of {@link #keySet()} or {@link #toString(int)}'s output:
     * By choosing a sorted map, the output will be ordered by key.
     * By choosing a linked map, the output will be in insertion order (oder of put calls).
     * <p>Example call with Java 8 function reference syntax:
     * <code>JSONObject o = new JSONObject(LinkedHashMap::new);</code>
     * <p>In Java 6 and 7 you'll need to create a class implementing the MapSupplier interface instead (which may be an anonymous inner class).</p>
     * @param mapSupplier Supplier for a new map, typically a method reference to a constructor or factory method.
     */
    public JSONObject(MapSupplier mapSupplier) {
        this.map = mapSupplier.get();
    }

    /**
     * Construct a JSONObject from a subset of another JSONObject. An array of
     * strings is used to identify the keys that should be copied. Missing keys
     * are ignored.
     *
     * @param jo
     *            A JSONObject.
     * @param names
     *            An array of strings.
     */
    public JSONObject(JSONObject jo, String[] names) {
        this(names.length);
        for (int i = 0; i < names.length; i += 1) {
            try {
                this.putOnce(names[i], jo.opt(names[i]));
            } catch (Exception ignore) {
            }
        }
    }

    /**
     * Construct a JSONObject from a JSONTokener.
     *
     * @param x
     *            A JSONTokener object containing the source string.
     * @throws JSONException
     *             If there is a syntax error in the source string or a
     *             duplicated key.
     */
    public JSONObject(JSONTokener x) throws JSONException {
        this();
        char c;
        String key;

        if (x.nextClean() != '{') {
            throw x.syntaxError("A JSONObject text must begin with '{'");
        }
        for (;;) {
            c = x.nextClean();
            switch (c) {
            case 0:
                throw x.syntaxError("A JSONObject text must end with '}'");
            case '}':
                return;
            default:
                x.back();
                key = x.nextValue().toString();
            }

            // The key is followed by ':'.

            c = x.nextClean();
            if (c != ':') {
                throw x.syntaxError("Expected a ':' after a key");
            }
            
            // Use syntaxError(..) to include error location
            
            if (key != null) {
                // Check if key exists
                if (this.opt(key) != null) {
                    // key already exists
                    throw x.syntaxError("Duplicate key \"" + key + "\"");
                }
                // Only add value if non-null
                Object value = x.nextValue();
                if (value!=null) {
                    this.put(key, value);
                }
            }

            // Pairs are separated by ','.

            switch (x.nextClean()) {
            case ';':
            case ',':
                if (x.nextClean() == '}') {
                    return;
                }
                x.back();
                break;
            case '}':
                return;
            default:
                throw x.syntaxError("Expected a ',' or '}'");
            }
        }
    }

    /**
     * Construct a JSONObject from a Map.
     *
     * @param m
     *            A map object that can be used to initialize the contents of
     *            the JSONObject.
     * @throws JSONException
     *            If a value in the map is non-finite number.
     * @throws NullPointerException
     *            If a key in the map is <code>null</code>
     */
    public JSONObject(Map<?, ?> m) {
        if (m == null) {
            this.map = new HashMap<String, Object>();
        } else {
            this.map = new HashMap<String, Object>(m.size());
        	for (final Entry<?, ?> e : m.entrySet()) {
        	    if(e.getKey() == null) {
        	        throw new NullPointerException("Null key.");
        	    }
                final Object value = e.getValue();
                if (value != null) {
                    this.map.put(String.valueOf(e.getKey()), wrap(value));
                }
            }
        }
    }

    /**
     * Construct a JSONObject from an Object using bean getters. It reflects on
     * all of the public methods of the object. For each of the methods with no
     * parameters and a name starting with <code>"get"</code> or
     * <code>"is"</code> followed by an uppercase letter, the method is invoked,
     * and a key and the value returned from the getter method are put into the
     * new JSONObject.
     * <p>
     * The key is formed by removing the <code>"get"</code> or <code>"is"</code>
     * prefix. If the second remaining character is not upper case, then the
     * first character is converted to lower case.
     * <p>
     * Methods that are <code>static</code>, return <code>void</code>,
     * have parameters, or are "bridge" methods, are ignored.
     * <p>
     * For example, if an object has a method named <code>"getName"</code>, and
     * if the result of calling <code>object.getName()</code> is
     * <code>"Larry Fine"</code>, then the JSONObject will contain
     * <code>"name": "Larry Fine"</code>.
     * <p>
     * The {@link JSONPropertyName} annotation can be used on a bean getter to
     * override key name used in the JSONObject. For example, using the object
     * above with the <code>getName</code> method, if we annotated it with:
     * <pre>
     * &#64;JSONPropertyName("FullName")
     * public String getName() { return this.name; }
     * </pre>
     * The resulting JSON object would contain <code>"FullName": "Larry Fine"</code>
     * <p>
     * Similarly, the {@link JSONPropertyName} annotation can be used on non-
     * <code>get</code> and <code>is</code> methods. We can also override key
     * name used in the JSONObject as seen below even though the field would normally
     * be ignored:
     * <pre>
     * &#64;JSONPropertyName("FullName")
     * public String fullName() { return this.name; }
     * </pre>
     * The resulting JSON object would contain <code>"FullName": "Larry Fine"</code>
     * <p>
     * The {@link JSONPropertyIgnore} annotation can be used to force the bean property
     * to not be serialized into JSON. If both {@link JSONPropertyIgnore} and
     * {@link JSONPropertyName} are defined on the same method, a depth comparison is
     * performed and the one closest to the concrete class being serialized is used.
     * If both annotations are at the same level, then the {@link JSONPropertyIgnore}
     * annotation takes precedent and the field is not serialized.
     * For example, the following declaration would prevent the <code>getName</code>
     * method from being serialized:
     * <pre>
     * &#64;JSONPropertyName("FullName")
     * &#64;JSONPropertyIgnore 
     * public String getName() { return this.name; }
     * </pre>
     * <p>
     * 
     * @param bean
     *            An object that has getter methods that should be used to make
     *            a JSONObject.
     */
    public JSONObject(Object bean) {
        this();
        this.populateMap(bean);
    }

    /**
     * Construct a JSONObject from an Object, using reflection to find the
     * public members. The resulting JSONObject's keys will be the strings from
     * the names array, and the values will be the field values associated with
     * those keys in the object. If a key is not found or not visible, then it
     * will not be copied into the new JSONObject.
     *
     * @param object
     *            An object that has fields that should be used to make a
     *            JSONObject.
     * @param names
     *            An array of strings, the names of the fields to be obtained
     *            from the object.
     */
    public JSONObject(Object object, String names[]) {
        this(names.length);
        Class<?> c = object.getClass();
        for (int i = 0; i < names.length; i += 1) {
            String name = names[i];
            try {
                this.putOpt(name, c.getField(name).get(object));
            } catch (Exception ignore) {
            }
        }
    }

    /**
     * Construct a JSONObject from a source JSON text string. This is the most
     * commonly used JSONObject constructor.
     *
     * @param source
     *            A string beginning with <code>{</code>&nbsp;<small>(left
     *            brace)</small> and ending with <code>}</code>
     *            &nbsp;<small>(right brace)</small>.
     * @exception JSONException
     *                If there is a syntax error in the source string or a
     *                duplicated key.
     */
    public JSONObject(String source) throws JSONException {
        this(new JSONTokener(source));
    }

    /**
     * Construct a JSONObject from a ResourceBundle.
     *
     * @param baseName
     *            The ResourceBundle base name.
     * @param locale
     *            The Locale to load the ResourceBundle for.
     * @throws JSONException
     *             If any JSONExceptions are detected.
     */
    public JSONObject(String baseName, Locale locale) throws JSONException {
        this();
        ResourceBundle bundle = ResourceBundle.getBundle(baseName, locale,
                Thread.currentThread().getContextClassLoader());

// Iterate through the keys in the bundle.

        Enumeration<String> keys = bundle.getKeys();
        while (keys.hasMoreElements()) {
            Object key = keys.nextElement();
            if (key != null) {

// Go through the path, ensuring that there is a nested JSONObject for each
// segment except the last. Add the value using the last segment's name into
// the deepest nested JSONObject.

                String[] path = ((String) key).split("\\.");
                int last = path.length - 1;
                JSONObject target = this;
                for (int i = 0; i < last; i += 1) {
                    String segment = path[i];
                    JSONObject nextTarget = target.optJSONObject(segment);
                    if (nextTarget == null) {
                        nextTarget = new JSONObject();
                        target.put(segment, nextTarget);
                    }
                    target = nextTarget;
                }
                target.put(path[last], bundle.getString((String) key));
            }
        }
    }
    
    /**
     * Constructor to specify an initial capacity of the internal map. Useful for library 
     * internal calls where we know, or at least can best guess, how big this JSONObject
     * will be.
     * 
     * @param initialCapacity initial capacity of the internal map.
     */
    protected JSONObject(int initialCapacity){
        this.map = new HashMap<String, Object>(initialCapacity);
    }

    /**
     * Accumulate values under a key. It is similar to the put method except
     * that if there is already an object stored under the key then a JSONArray
     * is stored under the key to hold all of the accumulated values. If there
     * is already a JSONArray, then the new value is appended to it. In
     * contrast, the put method replaces the previous value.
     *
     * If only one value is accumulated that is not a JSONArray, then the result
     * will be the same as using put. But if multiple values are accumulated,
     * then the result will be like append.
     *
     * @param key
     *            A key string.
     * @param value
     *            An object to be accumulated under the key.
     * @return this.
     * @throws JSONException
     *            If the value is non-finite number.
     * @throws NullPointerException
     *            If the key is <code>null</code>.
     */
    public JSONObject accumulate(String key, Object value) throws JSONException {
        testValidity(value);
        Object object = this.opt(key);
        if (object == null) {
            this.put(key,
                    value instanceof JSONArray ? new JSONArray().put(value)
                            : value);
        } else if (object instanceof JSONArray) {
            ((JSONArray) object).put(value);
        } else {
            this.put(key, new JSONArray().put(object).put(value));
        }
        return this;
    }

    /**
     * Append values to the array under a key. If the key does not exist in the
     * JSONObject, then the key is put in the JSONObject with its value being a
     * JSONArray containing the value parameter. If the key was already
     * associated with a JSONArray, then the value parameter is appended to it.
     *
     * @param key
     *            A key string.
     * @param value
     *            An object to be accumulated under the key.
     * @return this.
     * @throws JSONException
     *            If the value is non-finite number or if the current value associated with
     *             the key is not a JSONArray.
     * @throws NullPointerException
     *            If the key is <code>null</code>.
     */
    public JSONObject append(String key, Object value) throws JSONException {
        testValidity(value);
        Object object = this.opt(key);
        if (object == null) {
            this.put(key, new JSONArray().put(value));
        } else if (object instanceof JSONArray) {
            this.put(key, ((JSONArray) object).put(value));
        } else {
            throw new JSONException("JSONObject[" + key
                    + "] is not a JSONArray.");
        }
        return this;
    }

    /**
     * Produce a string from a double. The string "null" will be returned if the
     * number is not finite.
     *
     * @param d
     *            A double.
     * @return A String.
     */
    public static String doubleToString(double d) {
        if (Double.isInfinite(d) || Double.isNaN(d)) {
            return "null";
        }

// Shave off trailing zeros and decimal point, if possible.

        String string = Double.toString(d);
        if (string.indexOf('.') > 0 && string.indexOf('e') < 0
                && string.indexOf('E') < 0) {
            while (string.endsWith("0")) {
                string = string.substring(0, string.length() - 1);
            }
            if (string.endsWith(".")) {
                string = string.substring(0, string.length() - 1);
            }
        }
        return string;
    }

    /**
     * Get the value object associated with a key.
     *
     * @param key
     *            A key string.
     * @return The object associated with the key.
     * @throws JSONException
     *             if the key is not found.
     */
    public Object get(String key) throws JSONException {
        if (key == null) {
            throw new JSONException("Null key.");
        }
        Object object = this.opt(key);
        if (object == null) {
            throw new JSONException("JSONObject[" + quote(key) + "] not found.");
        }
        return object;
    }

    /**
     * Get the enum value associated with a key.
     * 
     * @param <E>
     *            Enum Type
     * @param clazz
     *           The type of enum to retrieve.
     * @param key
     *           A key string.
     * @return The enum value associated with the key
     * @throws JSONException
     *             if the key is not found or if the value cannot be converted
     *             to an enum.
     */
    public <E extends Enum<E>> E getEnum(Class<E> clazz, String key) throws JSONException {
        E val = optEnum(clazz, key);
        if(val==null) {
            // JSONException should really take a throwable argument.
            // If it did, I would re-implement this with the Enum.valueOf
            // method and place any thrown exception in the JSONException
            throw new JSONException("JSONObject[" + quote(key)
                    + "] is not an enum of type " + quote(clazz.getSimpleName())
                    + ".");
        }
        return val;
    }

    /**
     * Get the boolean value associated with a key.
     *
     * @param key
     *            A key string.
     * @return The truth.
     * @throws JSONException
     *             if the value is not a Boolean or the String "true" or
     *             "false".
     */
    public boolean getBoolean(String key) throws JSONException {
        Object object = this.get(key);
        if (object.equals(Boolean.FALSE)
                || (object instanceof String && ((String) object)
                        .equalsIgnoreCase("false"))) {
            return false;
        } else if (object.equals(Boolean.TRUE)
                || (object instanceof String && ((String) object)
                        .equalsIgnoreCase("true"))) {
            return true;
        }
        throw new JSONException("JSONObject[" + quote(key)
                + "] is not a Boolean.");
    }

    /**
     * Get the BigInteger value associated with a key.
     *
     * @param key
     *            A key string.
     * @return The numeric value.
     * @throws JSONException
     *             if the key is not found or if the value cannot 
     *             be converted to BigInteger.
     */
    public BigInteger getBigInteger(String key) throws JSONException {
        Object object = this.get(key);
        BigInteger ret = objectToBigInteger(object, null);
        if (ret != null) {
            return ret;
        }
        throw new JSONException("JSONObject[" + quote(key)
                + "] could not be converted to BigInteger (" + object + ").");
    }

    /**
     * Get the BigDecimal value associated with a key. If the value is float or
     * double, the the {@link BigDecimal#BigDecimal(double)} constructor will
     * be used. See notes on the constructor for conversion issues that may
     * arise.
     *
     * @param key
     *            A key string.
     * @return The numeric value.
     * @throws JSONException
     *             if the key is not found or if the value
     *             cannot be converted to BigDecimal.
     */
    public BigDecimal getBigDecimal(String key) throws JSONException {
        Object object = this.get(key);
        BigDecimal ret = objectToBigDecimal(object, null);
        if (ret != null) {
            return ret;
        }
        throw new JSONException("JSONObject[" + quote(key)
                + "] could not be converted to BigDecimal (" + object + ").");
    }

    /**
     * Get the double value associated with a key.
     *
     * @param key
     *            A key string.
     * @return The numeric value.
     * @throws JSONException
     *             if the key is not found or if the value is not a Number
     *             object and cannot be converted to a number.
     */
    public double getDouble(String key) throws JSONException {
        return this.getNumber(key).doubleValue();
    }

    /**
     * Get the float value associated with a key.
     *
     * @param key
     *            A key string.
     * @return The numeric value.
     * @throws JSONException
     *             if the key is not found or if the value is not a Number
     *             object and cannot be converted to a number.
     */
    public float getFloat(String key) throws JSONException {
        return this.getNumber(key).floatValue();
    }

    /**
     * Get the Number value associated with a key.
     *
     * @param key
     *            A key string.
     * @return The numeric value.
     * @throws JSONException
     *             if the key is not found or if the value is not a Number
     *             object and cannot be converted to a number.
     */
    public Number getNumber(String key) throws JSONException {
        Object object = this.get(key);
        try {
            if (object instanceof Number) {
                return (Number)object;
            }
            return stringToNumber(object.toString());
        } catch (Exception e) {
            throw new JSONException("JSONObject[" + quote(key)
                    + "] is not a number.", e);
        }
    }

    /**
     * Get the int value associated with a key.
     *
     * @param key
     *            A key string.
     * @return The integer value.
     * @throws JSONException
     *             if the key is not found or if the value cannot be converted
     *             to an integer.
     */
    public int getInt(String key) throws JSONException {
        return this.getNumber(key).intValue();
    }

    /**
     * Get the JSONArray value associated with a key.
     *
     * @param key
     *            A key string.
     * @return A JSONArray which is the value.
     * @throws JSONException
     *             if the key is not found or if the value is not a JSONArray.
     */
    public JSONArray getJSONArray(String key) throws JSONException {
        Object object = this.get(key);
        if (object instanceof JSONArray) {
            return (JSONArray) object;
        }
        throw new JSONException("JSONObject[" + quote(key)
                + "] is not a JSONArray.");
    }

    /**
     * Get the JSONObject value associated with a key.
     *
     * @param key
     *            A key string.
     * @return A JSONObject which is the value.
     * @throws JSONException
     *             if the key is not found or if the value is not a JSONObject.
     */
    public JSONObject getJSONObject(String key) throws JSONException {
        Object object = this.get(key);
        if (object instanceof JSONObject) {
            return (JSONObject) object;
        }
        throw new JSONException("JSONObject[" + quote(key)
                + "] is not a JSONObject.");
    }

    /**
     * Get the long value associated with a key.
     *
     * @param key
     *            A key string.
     * @return The long value.
     * @throws JSONException
     *             if the key is not found or if the value cannot be converted
     *             to a long.
     */
    public long getLong(String key) throws JSONException {
        return this.getNumber(key).longValue();
    }

    /**
     * Get an array of field names from a JSONObject.
     *
     * @param jo
     *            JSON object
     * @return An array of field names, or null if there are no names.
     */
    public static String[] getNames(JSONObject jo) {
        if (jo.isEmpty()) {
            return null;
        }
        return jo.keySet().toArray(new String[jo.length()]);
    }

    /**
     * Get an array of public field names from an Object.
     *
     * @param object
     *            object to read
     * @return An array of field names, or null if there are no names.
     */
    public static String[] getNames(Object object) {
        if (object == null) {
            return null;
        }
        Class<?> klass = object.getClass();
        Field[] fields = klass.getFields();
        int length = fields.length;
        if (length == 0) {
            return null;
        }
        String[] names = new String[length];
        for (int i = 0; i < length; i += 1) {
            names[i] = fields[i].getName();
        }
        return names;
    }

    /**
     * Get the string associated with a key.
     *
     * @param key
     *            A key string.
     * @return A string which is the value.
     * @throws JSONException
     *             if there is no string value for the key.
     */
    public String getString(String key) throws JSONException {
        Object object = this.get(key);
        if (object instanceof String) {
            return (String) object;
        }
        throw new JSONException("JSONObject[" + quote(key) + "] not a string.");
    }

    /**
     * Determine if the JSONObject contains a specific key.
     *
     * @param key
     *            A key string.
     * @return true if the key exists in the JSONObject.
     */
    public boolean has(String key) {
        return this.map.containsKey(key);
    }

    /**
     * Increment a property of a JSONObject. If there is no such property,
     * create one with a value of 1. If there is such a property, and if it is
     * an Integer, Long, Double, or Float, then add one to it.
     *
     * @param key
     *            A key string.
     * @return this.
     * @throws JSONException
     *             If there is already a property with this name that is not an
     *             Integer, Long, Double, or Float.
     */
    public JSONObject increment(String key) throws JSONException {
        Object value = this.opt(key);
        if (value == null) {
            this.put(key, 1);
        } else if (value instanceof BigInteger) {
            this.put(key, ((BigInteger)value).add(BigInteger.ONE));
        } else if (value instanceof BigDecimal) {
            this.put(key, ((BigDecimal)value).add(BigDecimal.ONE));
        } else if (value instanceof Integer) {
            this.put(key, ((Integer) value).intValue() + 1);
        } else if (value instanceof Long) {
            this.put(key, ((Long) value).longValue() + 1L);
        } else if (value instanceof Double) {
            this.put(key, ((Double) value).doubleValue() + 1.0d);
        } else if (value instanceof Float) {
            this.put(key, ((Float) value).floatValue() + 1.0f);
        } else {
            throw new JSONException("Unable to increment [" + quote(key) + "].");
        }
        return this;
    }

    /**
     * Determine if the value associated with the key is <code>null</code> or if there is no
     * value.
     *
     * @param key
     *            A key string.
     * @return true if there is no value associated with the key or if the value
     *        is the JSONObject.NULL object.
     */
    public boolean isNull(String key) {
        return JSONObject.NULL.equals(this.opt(key));
    }

    /**
     * Get an enumeration of the keys of the JSONObject. Modifying this key Set will also
     * modify the JSONObject. Use with caution.
     *
     * @see Set#iterator()
     * 
     * @return An iterator of the keys.
     */
    public Iterator<String> keys() {
        return this.keySet().iterator();
    }

    /**
     * Get a set of keys of the JSONObject. Modifying this key Set will also modify the
     * JSONObject. Use with caution.
     *
     * @see Map#keySet()
     *
     * @return A keySet.
     */
    public Set<String> keySet() {
        return this.map.keySet();
    }

    /**
     * Get a set of entries of the JSONObject. These are raw values and may not
     * match what is returned by the JSONObject get* and opt* functions. Modifying 
     * the returned EntrySet or the Entry objects contained therein will modify the
     * backing JSONObject. This does not return a clone or a read-only view.
     * 
     * Use with caution.
     *
     * @see Map#entrySet()
     *
     * @return An Entry Set
     */
    protected Set<Entry<String, Object>> entrySet() {
        return this.map.entrySet();
    }

    /**
     * Get the number of keys stored in the JSONObject.
     *
     * @return The number of keys in the JSONObject.
     */
    public int length() {
        return this.map.size();
    }

    /**
     * Check if JSONObject is empty.
     *
     * @return true if JSONObject is empty, otherwise false.
     */
    public boolean isEmpty() {
        return this.map.isEmpty();
    }

    /**
     * Produce a JSONArray containing the names of the elements of this
     * JSONObject.
     *
     * @return A JSONArray containing the key strings, or null if the JSONObject
     *        is empty.
     */
    public JSONArray names() {
    	if(this.map.isEmpty()) {
    		return null;
    	}
        return new JSONArray(this.map.keySet());
    }

    /**
     * Produce a string from a Number.
     *
     * @param number
     *            A Number
     * @return A String.
     * @throws JSONException
     *             If n is a non-finite number.
     */
    public static String numberToString(Number number) throws JSONException {
        if (number == null) {
            throw new JSONException("Null pointer");
        }
        testValidity(number);

        // Shave off trailing zeros and decimal point, if possible.

        String string = number.toString();
        if (string.indexOf('.') > 0 && string.indexOf('e') < 0
                && string.indexOf('E') < 0) {
            while (string.endsWith("0")) {
                string = string.substring(0, string.length() - 1);
            }
            if (string.endsWith(".")) {
                string = string.substring(0, string.length() - 1);
            }
        }
        return string;
    }

    /**
     * Get an optional value associated with a key.
     *
     * @param key
     *            A key string.
     * @return An object which is the value, or null if there is no value.
     */
    public Object opt(String key) {
        return key == null ? null : this.map.get(key);
    }

    /**
     * Get the enum value associated with a key.
     * 
     * @param <E>
     *            Enum Type
     * @param clazz
     *            The type of enum to retrieve.
     * @param key
     *            A key string.
     * @return The enum value associated with the key or null if not found
     */
    public <E extends Enum<E>> E optEnum(Class<E> clazz, String key) {
        return this.optEnum(clazz, key, null);
    }

    /**
     * Get the enum value associated with a key.
     * 
     * @param <E>
     *            Enum Type
     * @param clazz
     *            The type of enum to retrieve.
     * @param key
     *            A key string.
     * @param defaultValue
     *            The default in case the value is not found
     * @return The enum value associated with the key or defaultValue
     *            if the value is not found or cannot be assigned to <code>clazz</code>
     */
    public <E extends Enum<E>> E optEnum(Class<E> clazz, String key, E defaultValue) {
        try {
            Object val = this.opt(key);
            if (NULL.equals(val)) {
                return defaultValue;
            }
            if (clazz.isAssignableFrom(val.getClass())) {
                // we just checked it!
                @SuppressWarnings("unchecked")
                E myE = (E) val;
                return myE;
            }
            return Enum.valueOf(clazz, val.toString());
        } catch (IllegalArgumentException e) {
            return defaultValue;
        } catch (NullPointerException e) {
            return defaultValue;
        }
    }

    /**
     * Get an optional boolean associated with a key. It returns false if there
     * is no such key, or if the value is not Boolean.TRUE or the String "true".
     *
     * @param key
     *            A key string.
     * @return The truth.
     */
    public boolean optBoolean(String key) {
        return this.optBoolean(key, false);
    }

    /**
     * Get an optional boolean associated with a key. It returns the
     * defaultValue if there is no such key, or if it is not a Boolean or the
     * String "true" or "false" (case insensitive).
     *
     * @param key
     *            A key string.
     * @param defaultValue
     *            The default.
     * @return The truth.
     */
    public boolean optBoolean(String key, boolean defaultValue) {
        Object val = this.opt(key);
        if (NULL.equals(val)) {
            return defaultValue;
        }
        if (val instanceof Boolean){
            return ((Boolean) val).booleanValue();
        }
        try {
            // we'll use the get anyway because it does string conversion.
            return this.getBoolean(key);
        } catch (Exception e) {
            return defaultValue;
        }
    }

    /**
     * Get an optional BigDecimal associated with a key, or the defaultValue if
     * there is no such key or if its value is not a number. If the value is a
     * string, an attempt will be made to evaluate it as a number. If the value
     * is float or double, then the {@link BigDecimal#BigDecimal(double)}
     * constructor will be used. See notes on the constructor for conversion
     * issues that may arise.
     *
     * @param key
     *            A key string.
     * @param defaultValue
     *            The default.
     * @return An object which is the value.
     */
    public BigDecimal optBigDecimal(String key, BigDecimal defaultValue) {
        Object val = this.opt(key);
        return objectToBigDecimal(val, defaultValue);
    }

    /**
     * @param val value to convert
     * @param defaultValue default value to return is the conversion doesn't work or is null.
     * @return BigDecimal conversion of the original value, or the defaultValue if unable
     *          to convert. 
     */
    static BigDecimal objectToBigDecimal(Object val, BigDecimal defaultValue) {
        if (NULL.equals(val)) {
            return defaultValue;
        }
        if (val instanceof BigDecimal){
            return (BigDecimal) val;
        }
        if (val instanceof BigInteger){
            return new BigDecimal((BigInteger) val);
        }
        if (val instanceof Double || val instanceof Float){
            final double d = ((Number) val).doubleValue();
            if(Double.isNaN(d)) {
                return defaultValue;
            }
            return new BigDecimal(((Number) val).doubleValue());
        }
        if (val instanceof Long || val instanceof Integer
                || val instanceof Short || val instanceof Byte){
            return new BigDecimal(((Number) val).longValue());
        }
        // don't check if it's a string in case of unchecked Number subclasses
        try {
            return new BigDecimal(val.toString());
        } catch (Exception e) {
            return defaultValue;
        }
    }

    /**
     * Get an optional BigInteger associated with a key, or the defaultValue if
     * there is no such key or if its value is not a number. If the value is a
     * string, an attempt will be made to evaluate it as a number.
     *
     * @param key
     *            A key string.
     * @param defaultValue
     *            The default.
     * @return An object which is the value.
     */
    public BigInteger optBigInteger(String key, BigInteger defaultValue) {
        Object val = this.opt(key);
        return objectToBigInteger(val, defaultValue);
    }

    /**
     * @param val value to convert
     * @param defaultValue default value to return is the conversion doesn't work or is null.
     * @return BigInteger conversion of the original value, or the defaultValue if unable
     *          to convert. 
     */
    static BigInteger objectToBigInteger(Object val, BigInteger defaultValue) {
        if (NULL.equals(val)) {
            return defaultValue;
        }
        if (val instanceof BigInteger){
            return (BigInteger) val;
        }
        if (val instanceof BigDecimal){
            return ((BigDecimal) val).toBigInteger();
        }
        if (val instanceof Double || val instanceof Float){
            final double d = ((Number) val).doubleValue();
            if(Double.isNaN(d)) {
                return defaultValue;
            }
            return new BigDecimal(d).toBigInteger();
        }
        if (val instanceof Long || val instanceof Integer
                || val instanceof Short || val instanceof Byte){
            return BigInteger.valueOf(((Number) val).longValue());
        }
        // don't check if it's a string in case of unchecked Number subclasses
        try {
            // the other opt functions handle implicit conversions, i.e. 
            // jo.put("double",1.1d);
            // jo.optInt("double"); -- will return 1, not an error
            // this conversion to BigDecimal then to BigInteger is to maintain
            // that type cast support that may truncate the decimal.
            final String valStr = val.toString();
            if(isDecimalNotation(valStr)) {
                return new BigDecimal(valStr).toBigInteger();
            }
            return new BigInteger(valStr);
        } catch (Exception e) {
            return defaultValue;
        }
    }

    /**
     * Get an optional double associated with a key, or NaN if there is no such
     * key or if its value is not a number. If the value is a string, an attempt
     * will be made to evaluate it as a number.
     *
     * @param key
     *            A string which is the key.
     * @return An object which is the value.
     */
    public double optDouble(String key) {
        return this.optDouble(key, Double.NaN);
    }

    /**
     * Get an optional double associated with a key, or the defaultValue if
     * there is no such key or if its value is not a number. If the value is a
     * string, an attempt will be made to evaluate it as a number.
     *
     * @param key
     *            A key string.
     * @param defaultValue
     *            The default.
     * @return An object which is the value.
     */
    public double optDouble(String key, double defaultValue) {
        Number val = this.optNumber(key);
        if (val == null) {
            return defaultValue;
        }
        final double doubleValue = val.doubleValue();
        // if (Double.isNaN(doubleValue) || Double.isInfinite(doubleValue)) {
        // return defaultValue;
        // }
        return doubleValue;
    }

    /**
     * Get the optional double value associated with an index. NaN is returned
     * if there is no value for the index, or if the value is not a number and
     * cannot be converted to a number.
     *
     * @param key
     *            A key string.
     * @return The value.
     */
    public float optFloat(String key) {
        return this.optFloat(key, Float.NaN);
    }

    /**
     * Get the optional double value associated with an index. The defaultValue
     * is returned if there is no value for the index, or if the value is not a
     * number and cannot be converted to a number.
     *
     * @param key
     *            A key string.
     * @param defaultValue
     *            The default value.
     * @return The value.
     */
    public float optFloat(String key, float defaultValue) {
        Number val = this.optNumber(key);
        if (val == null) {
            return defaultValue;
        }
        final float floatValue = val.floatValue();
        // if (Float.isNaN(floatValue) || Float.isInfinite(floatValue)) {
        // return defaultValue;
        // }
        return floatValue;
    }

    /**
     * Get an optional int value associated with a key, or zero if there is no
     * such key or if the value is not a number. If the value is a string, an
     * attempt will be made to evaluate it as a number.
     *
     * @param key
     *            A key string.
     * @return An object which is the value.
     */
    public int optInt(String key) {
        return this.optInt(key, 0);
    }

    /**
     * Get an optional int value associated with a key, or the default if there
     * is no such key or if the value is not a number. If the value is a string,
     * an attempt will be made to evaluate it as a number.
     *
     * @param key
     *            A key string.
     * @param defaultValue
     *            The default.
     * @return An object which is the value.
     */
    public int optInt(String key, int defaultValue) {
        final Number val = this.optNumber(key, null);
        if (val == null) {
            return defaultValue;
        }
        return val.intValue();
    }

    /**
     * Get an optional JSONArray associated with a key. It returns null if there
     * is no such key, or if its value is not a JSONArray.
     *
     * @param key
     *            A key string.
     * @return A JSONArray which is the value.
     */
    public JSONArray optJSONArray(String key) {
        Object o = this.opt(key);
        return o instanceof JSONArray ? (JSONArray) o : null;
    }

    /**
     * Get an optional JSONObject associated with a key. It returns null if
     * there is no such key, or if its value is not a JSONObject.
     *
     * @param key
     *            A key string.
     * @return A JSONObject which is the value.
     */
    public JSONObject optJSONObject(String key) {
        Object object = this.opt(key);
        return object instanceof JSONObject ? (JSONObject) object : null;
    }

    /**
     * Get an optional long value associated with a key, or zero if there is no
     * such key or if the value is not a number. If the value is a string, an
     * attempt will be made to evaluate it as a number.
     *
     * @param key
     *            A key string.
     * @return An object which is the value.
     */
    public long optLong(String key) {
        return this.optLong(key, 0);
    }

    /**
     * Get an optional long value associated with a key, or the default if there
     * is no such key or if the value is not a number. If the value is a string,
     * an attempt will be made to evaluate it as a number.
     *
     * @param key
     *            A key string.
     * @param defaultValue
     *            The default.
     * @return An object which is the value.
     */
    public long optLong(String key, long defaultValue) {
        final Number val = this.optNumber(key, null);
        if (val == null) {
            return defaultValue;
        }
        
        return val.longValue();
    }
    
    /**
     * Get an optional {@link Number} value associated with a key, or <code>null</code>
     * if there is no such key or if the value is not a number. If the value is a string,
     * an attempt will be made to evaluate it as a number ({@link BigDecimal}). This method
     * would be used in cases where type coercion of the number value is unwanted.
     *
     * @param key
     *            A key string.
     * @return An object which is the value.
     */
    public Number optNumber(String key) {
        return this.optNumber(key, null);
    }

    /**
     * Get an optional {@link Number} value associated with a key, or the default if there
     * is no such key or if the value is not a number. If the value is a string,
     * an attempt will be made to evaluate it as a number. This method
     * would be used in cases where type coercion of the number value is unwanted.
     *
     * @param key
     *            A key string.
     * @param defaultValue
     *            The default.
     * @return An object which is the value.
     */
    public Number optNumber(String key, Number defaultValue) {
        Object val = this.opt(key);
        if (NULL.equals(val)) {
            return defaultValue;
        }
        if (val instanceof Number){
            return (Number) val;
        }
        
        try {
            return stringToNumber(val.toString());
        } catch (Exception e) {
            return defaultValue;
        }
    }
    
    /**
     * Get an optional string associated with a key. It returns an empty string
     * if there is no such key. If the value is not a string and is not null,
     * then it is converted to a string.
     *
     * @param key
     *            A key string.
     * @return A string which is the value.
     */
    public String optString(String key) {
        return this.optString(key, "");
    }

    /**
     * Get an optional string associated with a key. It returns the defaultValue
     * if there is no such key.
     *
     * @param key
     *            A key string.
     * @param defaultValue
     *            The default.
     * @return A string which is the value.
     */
    public String optString(String key, String defaultValue) {
        Object object = this.opt(key);
        return NULL.equals(object) ? defaultValue : object.toString();
    }

    /**
     * Populates the internal map of the JSONObject with the bean properties. The
     * bean can not be recursive.
     *
     * @see JSONObject#JSONObject(Object)
     *
     * @param bean
     *            the bean
     */
    private void populateMap(Object bean) {
        Class<?> klass = bean.getClass();

        // If klass is a System class then set includeSuperClass to false.

        boolean includeSuperClass = klass.getClassLoader() != null;

        Method[] methods = includeSuperClass ? klass.getMethods() : klass.getDeclaredMethods();
        for (final Method method : methods) {
            final int modifiers = method.getModifiers();
            if (Modifier.isPublic(modifiers)
                    && !Modifier.isStatic(modifiers)
                    && method.getParameterTypes().length == 0
                    && !method.isBridge()
                    && method.getReturnType() != Void.TYPE
                    && isValidMethodName(method.getName())) {
                final String key = getKeyNameFromMethod(method);
                if (key != null && !key.isEmpty()) {
                    try {
                        final Object result = method.invoke(bean);
                        if (result != null) {
                            this.map.put(key, wrap(result));
                            // we don't use the result anywhere outside of wrap
                            // if it's a resource we should be sure to close it
                            // after calling toString
                            if (result instanceof Closeable) {
                                try {
                                    ((Closeable) result).close();
                                } catch (IOException ignore) {
                                }
                            }
                        }
                    } catch (IllegalAccessException ignore) {
                    } catch (IllegalArgumentException ignore) {
                    } catch (InvocationTargetException ignore) {
                    }
                }
            }
        }
    }

    private boolean isValidMethodName(String name) {
        return !"getClass".equals(name) && !"getDeclaringClass".equals(name);
    }

    private String getKeyNameFromMethod(Method method) {
        final int ignoreDepth = getAnnotationDepth(method, JSONPropertyIgnore.class);
        if (ignoreDepth > 0) {
            final int forcedNameDepth = getAnnotationDepth(method, JSONPropertyName.class);
            if (forcedNameDepth < 0 || ignoreDepth <= forcedNameDepth) {
                // the hierarchy asked to ignore, and the nearest name override
                // was higher or non-existent
                return null;
            }
        }
        JSONPropertyName annotation = getAnnotation(method, JSONPropertyName.class);
        if (annotation != null && annotation.value() != null && !annotation.value().isEmpty()) {
            return annotation.value();
        }
        String key;
        final String name = method.getName();
        if (name.startsWith("get") && name.length() > 3) {
            key = name.substring(3);
        } else if (name.startsWith("is") && name.length() > 2) {
            key = name.substring(2);
        } else {
            return null;
        }
        // if the first letter in the key is not uppercase, then skip.
        // This is to maintain backwards compatibility before PR406
        // (https://github.com/stleary/JSON-java/pull/406/)
        if (Character.isLowerCase(key.charAt(0))) {
            return null;
        }
        if (key.length() == 1) {
            key = key.toLowerCase(Locale.ROOT);
        } else if (!Character.isUpperCase(key.charAt(1))) {
            key = key.substring(0, 1).toLowerCase(Locale.ROOT) + key.substring(1);
        }
        return key;
    }

    /**
     * Searches the class hierarchy to see if the method or it's super
     * implementations and interfaces has the annotation.
     *
     * @param <A>
     *            type of the annotation
     *
     * @param m
     *            method to check
     * @param annotationClass
     *            annotation to look for
     * @return the {@link Annotation} if the annotation exists on the current method
     *         or one of it's super class definitions
     */
    private static <A extends Annotation> A getAnnotation(final Method m, final Class<A> annotationClass) {
        // if we have invalid data the result is null
        if (m == null || annotationClass == null) {
            return null;
        }

        if (m.isAnnotationPresent(annotationClass)) {
            return m.getAnnotation(annotationClass);
        }

        // if we've already reached the Object class, return null;
        Class<?> c = m.getDeclaringClass();
        if (c.getSuperclass() == null) {
            return null;
        }

        // check directly implemented interfaces for the method being checked
        for (Class<?> i : c.getInterfaces()) {
            try {
                Method im = i.getMethod(m.getName(), m.getParameterTypes());
                return getAnnotation(im, annotationClass);
            } catch (final SecurityException ex) {
                continue;
            } catch (final NoSuchMethodException ex) {
                continue;
            }
        }

        try {
            return getAnnotation(
                    c.getSuperclass().getMethod(m.getName(), m.getParameterTypes()),
                    annotationClass);
        } catch (final SecurityException ex) {
            return null;
        } catch (final NoSuchMethodException ex) {
            return null;
        }
    }

    /**
     * Searches the class hierarchy to see if the method or it's super
     * implementations and interfaces has the annotation. Returns the depth of the
     * annotation in the hierarchy.
     *
     * @param <A>
     *            type of the annotation
     *
     * @param m
     *            method to check
     * @param annotationClass
     *            annotation to look for
     * @return Depth of the annotation or -1 if the annotation is not on the method.
     */
    private static int getAnnotationDepth(final Method m, final Class<? extends Annotation> annotationClass) {
        // if we have invalid data the result is -1
        if (m == null || annotationClass == null) {
            return -1;
        }

        if (m.isAnnotationPresent(annotationClass)) {
            return 1;
        }

        // if we've already reached the Object class, return -1;
        Class<?> c = m.getDeclaringClass();
        if (c.getSuperclass() == null) {
            return -1;
        }

        // check directly implemented interfaces for the method being checked
        for (Class<?> i : c.getInterfaces()) {
            try {
                Method im = i.getMethod(m.getName(), m.getParameterTypes());
                int d = getAnnotationDepth(im, annotationClass);
                if (d > 0) {
                    // since the annotation was on the interface, add 1
                    return d + 1;
                }
            } catch (final SecurityException ex) {
                continue;
            } catch (final NoSuchMethodException ex) {
                continue;
            }
        }

        try {
            int d = getAnnotationDepth(
                    c.getSuperclass().getMethod(m.getName(), m.getParameterTypes()),
                    annotationClass);
            if (d > 0) {
                // since the annotation was on the superclass, add 1
                return d + 1;
            }
            return -1;
        } catch (final SecurityException ex) {
            return -1;
        } catch (final NoSuchMethodException ex) {
            return -1;
        }
    }

    /**
     * Put a key/boolean pair in the JSONObject.
     *
     * @param key
     *            A key string.
     * @param value
     *            A boolean which is the value.
     * @return this.
     * @throws JSONException
     *            If the value is non-finite number.
     * @throws NullPointerException
     *            If the key is <code>null</code>.
     */
    public JSONObject put(String key, boolean value) throws JSONException {
        return this.put(key, value ? Boolean.TRUE : Boolean.FALSE);
    }

    /**
     * Put a key/value pair in the JSONObject, where the value will be a
     * JSONArray which is produced from a Collection.
     *
     * @param key
     *            A key string.
     * @param value
     *            A Collection value.
     * @return this.
     * @throws JSONException
     *            If the value is non-finite number.
     * @throws NullPointerException
     *            If the key is <code>null</code>.
     */
    public JSONObject put(String key, Collection<?> value) throws JSONException {
        return this.put(key, new JSONArray(value));
    }

    /**
     * Put a key/double pair in the JSONObject.
     *
     * @param key
     *            A key string.
     * @param value
     *            A double which is the value.
     * @return this.
     * @throws JSONException
     *            If the value is non-finite number.
     * @throws NullPointerException
     *            If the key is <code>null</code>.
     */
    public JSONObject put(String key, double value) throws JSONException {
        return this.put(key, Double.valueOf(value));
    }
    
    /**
     * Put a key/float pair in the JSONObject.
     *
     * @param key
     *            A key string.
     * @param value
     *            A float which is the value.
     * @return this.
     * @throws JSONException
     *            If the value is non-finite number.
     * @throws NullPointerException
     *            If the key is <code>null</code>.
     */
    public JSONObject put(String key, float value) throws JSONException {
        return this.put(key, Float.valueOf(value));
    }

    /**
     * Put a key/int pair in the JSONObject.
     *
     * @param key
     *            A key string.
     * @param value
     *            An int which is the value.
     * @return this.
     * @throws JSONException
     *            If the value is non-finite number.
     * @throws NullPointerException
     *            If the key is <code>null</code>.
     */
    public JSONObject put(String key, int value) throws JSONException {
        return this.put(key, Integer.valueOf(value));
    }

    /**
     * Put a key/long pair in the JSONObject.
     *
     * @param key
     *            A key string.
     * @param value
     *            A long which is the value.
     * @return this.
     * @throws JSONException
     *            If the value is non-finite number.
     * @throws NullPointerException
     *            If the key is <code>null</code>.
     */
    public JSONObject put(String key, long value) throws JSONException {
        return this.put(key, Long.valueOf(value));
    }

    /**
     * Put a key/value pair in the JSONObject, where the value will be a
     * JSONObject which is produced from a Map.
     *
     * @param key
     *            A key string.
     * @param value
     *            A Map value.
     * @return this.
     * @throws JSONException
     *            If the value is non-finite number.
     * @throws NullPointerException
     *            If the key is <code>null</code>.
     */
    public JSONObject put(String key, Map<?, ?> value) throws JSONException {
        return this.put(key, new JSONObject(value));
    }

    /**
     * Put a key/value pair in the JSONObject. If the value is <code>null</code>, then the
     * key will be removed from the JSONObject if it is present.
     *
     * @param key
     *            A key string.
     * @param value
     *            An object which is the value. It should be of one of these
     *            types: Boolean, Double, Integer, JSONArray, JSONObject, Long,
     *            String, or the JSONObject.NULL object.
     * @return this.
     * @throws JSONException
     *            If the value is non-finite number.
     * @throws NullPointerException
     *            If the key is <code>null</code>.
     */
    public JSONObject put(String key, Object value) throws JSONException {
        if (key == null) {
            throw new NullPointerException("Null key.");
        }
        if (value != null) {
            testValidity(value);
            this.map.put(key, value);
        } else {
            this.remove(key);
        }
        return this;
    }

    /**
     * Put a key/value pair in the JSONObject, but only if the key and the value
     * are both non-null, and only if there is not already a member with that
     * name.
     *
     * @param key
     *            key to insert into
     * @param value
     *            value to insert
     * @return this.
     * @throws JSONException
     *             if the key is a duplicate
     */
    public JSONObject putOnce(String key, Object value) throws JSONException {
        if (key != null && value != null) {
            if (this.opt(key) != null) {
                throw new JSONException("Duplicate key \"" + key + "\"");
            }
            return this.put(key, value);
        }
        return this;
    }

    /**
     * Put a key/value pair in the JSONObject, but only if the key and the value
     * are both non-null.
     *
     * @param key
     *            A key string.
     * @param value
     *            An object which is the value. It should be of one of these
     *            types: Boolean, Double, Integer, JSONArray, JSONObject, Long,
     *            String, or the JSONObject.NULL object.
     * @return this.
     * @throws JSONException
     *             If the value is a non-finite number.
     */
    public JSONObject putOpt(String key, Object value) throws JSONException {
        if (key != null && value != null) {
            return this.put(key, value);
        }
        return this;
    }

    /**
     * Creates a JSONPointer using an initialization string and tries to 
     * match it to an item within this JSONObject. For example, given a
     * JSONObject initialized with this document:
     * <pre>
     * {
     *     "a":{"b":"c"}
     * }
     * </pre>
     * and this JSONPointer string: 
     * <pre>
     * "/a/b"
     * </pre>
     * Then this method will return the String "c".
     * A JSONPointerException may be thrown from code called by this method.
     *   
     * @param jsonPointer string that can be used to create a JSONPointer
     * @return the item matched by the JSONPointer, otherwise null
     */
    public Object query(String jsonPointer) {
        return query(new JSONPointer(jsonPointer));
    }
    /**
     * Uses a user initialized JSONPointer  and tries to 
     * match it to an item within this JSONObject. For example, given a
     * JSONObject initialized with this document:
     * <pre>
     * {
     *     "a":{"b":"c"}
     * }
     * </pre>
     * and this JSONPointer: 
     * <pre>
     * "/a/b"
     * </pre>
     * Then this method will return the String "c".
     * A JSONPointerException may be thrown from code called by this method.
     *   
     * @param jsonPointer string that can be used to create a JSONPointer
     * @return the item matched by the JSONPointer, otherwise null
     */
    public Object query(JSONPointer jsonPointer) {
        return jsonPointer.queryFrom(this);
    }
    
    /**
     * Queries and returns a value from this object using {@code jsonPointer}, or
     * returns null if the query fails due to a missing key.
     * 
     * @param jsonPointer the string representation of the JSON pointer
     * @return the queried value or {@code null}
     * @throws IllegalArgumentException if {@code jsonPointer} has invalid syntax
     */
    public Object optQuery(String jsonPointer) {
    	return optQuery(new JSONPointer(jsonPointer));
    }
    
    /**
     * Queries and returns a value from this object using {@code jsonPointer}, or
     * returns null if the query fails due to a missing key.
     * 
     * @param jsonPointer The JSON pointer
     * @return the queried value or {@code null}
     * @throws IllegalArgumentException if {@code jsonPointer} has invalid syntax
     */
    public Object optQuery(JSONPointer jsonPointer) {
        try {
            return jsonPointer.queryFrom(this);
        } catch (JSONPointerException e) {
            return null;
        }
    }

    /**
     * Produce a string in double quotes with backslash sequences in all the
     * right places. A backslash will be inserted within &lt;/, producing
     * &lt;\/, allowing JSON text to be delivered in HTML. In JSON text, a
     * string cannot contain a control character or an unescaped quote or
     * backslash.
     *
     * @param string
     *            A String
     * @return A String correctly formatted for insertion in a JSON text.
     */
    public static String quote(String string) {
        StringWriter sw = new StringWriter();
        synchronized (sw.getBuffer()) {
            try {
                return quote(string, sw).toString();
            } catch (IOException ignored) {
                // will never happen - we are writing to a string writer
                return "";
            }
        }
    }

    public static Writer quote(String string, Writer w) throws IOException {
        if (string == null || string.isEmpty()) {
            w.write("\"\"");
            return w;
        }

        char b;
        char c = 0;
        String hhhh;
        int i;
        int len = string.length();

        w.write('"');
        for (i = 0; i < len; i += 1) {
            b = c;
            c = string.charAt(i);
            switch (c) {
            case '\\':
            case '"':
                w.write('\\');
                w.write(c);
                break;
            case '/':
                if (b == '<') {
                    w.write('\\');
                }
                w.write(c);
                break;
            case '\b':
                w.write("\\b");
                break;
            case '\t':
                w.write("\\t");
                break;
            case '\n':
                w.write("\\n");
                break;
            case '\f':
                w.write("\\f");
                break;
            case '\r':
                w.write("\\r");
                break;
            default:
                if (c < ' ' || (c >= '\u0080' && c < '\u00a0')
                        || (c >= '\u2000' && c < '\u2100')) {
                    w.write("\\u");
                    hhhh = Integer.toHexString(c);
                    w.write("0000", 0, 4 - hhhh.length());
                    w.write(hhhh);
                } else {
                    w.write(c);
                }
            }
        }
        w.write('"');
        return w;
    }

    /**
     * Remove a name and its value, if present.
     *
     * @param key
     *            The name to be removed.
     * @return The value that was associated with the name, or null if there was
     *         no value.
     */
    public Object remove(String key) {
        return this.map.remove(key);
    }

    /**
     * Determine if two JSONObjects are similar.
     * They must contain the same set of names which must be associated with
     * similar values.
     *
     * @param other The other JSONObject
     * @return true if they are equal
     */
    public boolean similar(Object other) {
        try {
            if (!(other instanceof JSONObject)) {
                return false;
            }
            if (!this.keySet().equals(((JSONObject)other).keySet())) {
                return false;
            }
            for (final Entry<String,?> entry : this.entrySet()) {
                String name = entry.getKey();
                Object valueThis = entry.getValue();
                Object valueOther = ((JSONObject)other).get(name);
                if(valueThis == valueOther) {
                	continue;
                }
                if(valueThis == null) {
                	return false;
                }
                if (valueThis instanceof JSONObject) {
                    if (!((JSONObject)valueThis).similar(valueOther)) {
                        return false;
                    }
                } else if (valueThis instanceof JSONArray) {
                    if (!((JSONArray)valueThis).similar(valueOther)) {
                        return false;
                    }
                } else if (!valueThis.equals(valueOther)) {
                    return false;
                }
            }
            return true;
        } catch (Throwable exception) {
            return false;
        }
    }
    
    /**
     * Tests if the value should be tried as a decimal. It makes no test if there are actual digits.
     * 
     * @param val value to test
     * @return true if the string is "-0" or if it contains '.', 'e', or 'E', false otherwise.
     */
    protected static boolean isDecimalNotation(final String val) {
        return val.indexOf('.') > -1 || val.indexOf('e') > -1
                || val.indexOf('E') > -1 || "-0".equals(val);
    }
    
    /**
     * Converts a string to a number using the narrowest possible type. Possible 
     * returns for this function are BigDecimal, Double, BigInteger, Long, and Integer.
     * When a Double is returned, it should always be a valid Double and not NaN or +-infinity.
     * 
     * @param val value to convert
     * @return Number representation of the value.
     * @throws NumberFormatException thrown if the value is not a valid number. A public
     *      caller should catch this and wrap it in a {@link JSONException} if applicable.
     */
    protected static Number stringToNumber(final String val) throws NumberFormatException {
        char initial = val.charAt(0);
        if ((initial >= '0' && initial <= '9') || initial == '-') {
            // decimal representation
            if (isDecimalNotation(val)) {
                // quick dirty way to see if we need a BigDecimal instead of a Double
                // this only handles some cases of overflow or underflow
                if (val.length()>14) {
                    return new BigDecimal(val);
                }
                final Double d = Double.valueOf(val);
                if (d.isInfinite() || d.isNaN()) {
                    // if we can't parse it as a double, go up to BigDecimal
                    // this is probably due to underflow like 4.32e-678
                    // or overflow like 4.65e5324. The size of the string is small
                    // but can't be held in a Double.
                    return new BigDecimal(val);
                }
                return d;
            }
            // integer representation.
            // This will narrow any values to the smallest reasonable Object representation
            // (Integer, Long, or BigInteger)
            
            // string version
            // The compare string length method reduces GC,
            // but leads to smaller integers being placed in larger wrappers even though not
            // needed. i.e. 1,000,000,000 -> Long even though it's an Integer
            // 1,000,000,000,000,000,000 -> BigInteger even though it's a Long
            //if(val.length()<=9){
            //    return Integer.valueOf(val);
            //}
            //if(val.length()<=18){
            //    return Long.valueOf(val);
            //}
            //return new BigInteger(val);
            
            // BigInteger version: We use a similar bitLenth compare as
            // BigInteger#intValueExact uses. Increases GC, but objects hold
            // only what they need. i.e. Less runtime overhead if the value is
            // long lived. Which is the better tradeoff? This is closer to what's
            // in stringToValue.
            BigInteger bi = new BigInteger(val);
            if(bi.bitLength()<=31){
                return Integer.valueOf(bi.intValue());
            }
            if(bi.bitLength()<=63){
                return Long.valueOf(bi.longValue());
            }
            return bi;
        }
        throw new NumberFormatException("val ["+val+"] is not a valid number.");
    }

    /**
     * Try to convert a string into a number, boolean, or null. If the string
     * can't be converted, return the string.
     *
     * @param string
     *            A String. can not be null.
     * @return A simple JSON value.
     * @throws NullPointerException
     *             Thrown if the string is null.
     */
    // Changes to this method must be copied to the corresponding method in
    // the XML class to keep full support for Android
    public static Object stringToValue(String string) {
        if ("".equals(string)) {
            return string;
        }

        // check JSON key words true/false/null
        if ("true".equalsIgnoreCase(string)) {
            return Boolean.TRUE;
        }
        if ("false".equalsIgnoreCase(string)) {
            return Boolean.FALSE;
        }
        if ("null".equalsIgnoreCase(string)) {
            return JSONObject.NULL;
        }

        /*
         * If it might be a number, try converting it. If a number cannot be
         * produced, then the value will just be a string.
         */

        char initial = string.charAt(0);
        if ((initial >= '0' && initial <= '9') || initial == '-') {
            try {
                // if we want full Big Number support the contents of this
                // `try` block can be replaced with:
                // return stringToNumber(string);
                if (isDecimalNotation(string)) {
                    Double d = Double.valueOf(string);
                    if (!d.isInfinite() && !d.isNaN()) {
                        return d;
                    }
                } else {
                    Long myLong = Long.valueOf(string);
                    if (string.equals(myLong.toString())) {
                        if (myLong.longValue() == myLong.intValue()) {
                            return Integer.valueOf(myLong.intValue());
                        }
                        return myLong;
                    }
                }
            } catch (Exception ignore) {
            }
        }
        return string;
    }

    /**
     * Throw an exception if the object is a NaN or infinite number.
     *
     * @param o
     *            The object to test.
     * @throws JSONException
     *             If o is a non-finite number.
     */
    public static void testValidity(Object o) throws JSONException {
        if (o != null) {
            if (o instanceof Double) {
                if (((Double) o).isInfinite() || ((Double) o).isNaN()) {
                    throw new JSONException(
                            "JSON does not allow non-finite numbers.");
                }
            } else if (o instanceof Float) {
                if (((Float) o).isInfinite() || ((Float) o).isNaN()) {
                    throw new JSONException(
                            "JSON does not allow non-finite numbers.");
                }
            }
        }
    }

    /**
     * Produce a JSONArray containing the values of the members of this
     * JSONObject.
     *
     * @param names
     *            A JSONArray containing a list of key strings. This determines
     *            the sequence of the values in the result.
     * @return A JSONArray of values.
     * @throws JSONException
     *             If any of the values are non-finite numbers.
     */
    public JSONArray toJSONArray(JSONArray names) throws JSONException {
        if (names == null || names.isEmpty()) {
            return null;
        }
        JSONArray ja = new JSONArray();
        for (int i = 0; i < names.length(); i += 1) {
            ja.put(this.opt(names.getString(i)));
        }
        return ja;
    }

    /**
     * Make a JSON text of this JSONObject. For compactness, no whitespace is
     * added. If this would not result in a syntactically correct JSON text,
     * then null will be returned instead.
     * <p><b>
     * Warning: This method assumes that the data structure is acyclical.
     * </b>
     * 
     * @return a printable, displayable, portable, transmittable representation
     *         of the object, beginning with <code>{</code>&nbsp;<small>(left
     *         brace)</small> and ending with <code>}</code>&nbsp;<small>(right
     *         brace)</small>.
     */
    @Override
    public String toString() {
        try {
            return this.toString(0);
        } catch (Exception e) {
            return null;
        }
    }

    /**
     * Make a pretty-printed JSON text of this JSONObject.
     * 
     * <p>If <code>indentFactor > 0</code> and the {@link JSONObject}
     * has only one key, then the object will be output on a single line:
     * <pre>{@code {"key": 1}}</pre>
     * 
     * <p>If an object has 2 or more keys, then it will be output across
     * multiple lines: <code><pre>{
     *  "key1": 1,
     *  "key2": "value 2",
     *  "key3": 3
     * }</pre></code>
     * <p><b>
     * Warning: This method assumes that the data structure is acyclical.
     * </b>
     *
     * @param indentFactor
     *            The number of spaces to add to each level of indentation.
     * @return a printable, displayable, portable, transmittable representation
     *         of the object, beginning with <code>{</code>&nbsp;<small>(left
     *         brace)</small> and ending with <code>}</code>&nbsp;<small>(right
     *         brace)</small>.
     * @throws JSONException
     *             If the object contains an invalid number.
     */
    public String toString(int indentFactor) throws JSONException {
        StringWriter w = new StringWriter();
        synchronized (w.getBuffer()) {
            return this.write(w, indentFactor, 0).toString();
        }
    }

    /**
     * Make a JSON text of an Object value. If the object has an
     * value.toJSONString() method, then that method will be used to produce the
     * JSON text. The method is required to produce a strictly conforming text.
     * If the object does not contain a toJSONString method (which is the most
     * common case), then a text will be produced by other means. If the value
     * is an array or Collection, then a JSONArray will be made from it and its
     * toJSONString method will be called. If the value is a MAP, then a
     * JSONObject will be made from it and its toJSONString method will be
     * called. Otherwise, the value's toString method will be called, and the
     * result will be quoted.
     *
     * <p>
     * Warning: This method assumes that the data structure is acyclical.
     *
     * @param value
     *            The value to be serialized.
     * @return a printable, displayable, transmittable representation of the
     *         object, beginning with <code>{</code>&nbsp;<small>(left
     *         brace)</small> and ending with <code>}</code>&nbsp;<small>(right
     *         brace)</small>.
     * @throws JSONException
     *             If the value is or contains an invalid number.
     */
    public static String valueToString(Object value) throws JSONException {
    	// moves the implementation to JSONWriter as:
    	// 1. It makes more sense to be part of the writer class
    	// 2. For Android support this method is not available. By implementing it in the Writer
    	//    Android users can use the writer with the built in Android JSONObject implementation.
        return JSONWriter.valueToString(value);
    }

    /**
     * Wrap an object, if necessary. If the object is <code>null</code>, return the NULL
     * object. If it is an array or collection, wrap it in a JSONArray. If it is
     * a map, wrap it in a JSONObject. If it is a standard property (Double,
     * String, et al) then it is already wrapped. Otherwise, if it comes from
     * one of the java packages, turn it into a string. And if it doesn't, try
     * to wrap it in a JSONObject. If the wrapping fails, then null is returned.
     *
     * @param object
     *            The object to wrap
     * @return The wrapped value
     */
    public static Object wrap(Object object) {
        try {
            if (object == null) {
                return NULL;
            }
            if (object instanceof JSONObject || object instanceof JSONArray
                    || NULL.equals(object) || object instanceof JSONString
                    || object instanceof Byte || object instanceof Character
                    || object instanceof Short || object instanceof Integer
                    || object instanceof Long || object instanceof Boolean
                    || object instanceof Float || object instanceof Double
                    || object instanceof String || object instanceof BigInteger
                    || object instanceof BigDecimal || object instanceof Enum) {
                return object;
            }

            if (object instanceof Collection) {
                Collection<?> coll = (Collection<?>) object;
                return new JSONArray(coll);
            }
            if (object.getClass().isArray()) {
                return new JSONArray(object);
            }
            if (object instanceof Map) {
                Map<?, ?> map = (Map<?, ?>) object;
                return new JSONObject(map);
            }
            Package objectPackage = object.getClass().getPackage();
            String objectPackageName = objectPackage != null ? objectPackage
                    .getName() : "";
            if (objectPackageName.startsWith("java.")
                    || objectPackageName.startsWith("javax.")
                    || object.getClass().getClassLoader() == null) {
                return object.toString();
            }
            return new JSONObject(object);
        } catch (Exception exception) {
            return null;
        }
    }

    /**
     * Write the contents of the JSONObject as JSON text to a writer. For
     * compactness, no whitespace is added.
     * <p><b>
     * Warning: This method assumes that the data structure is acyclical.
     * </b>
     * 
     * @return The writer.
     * @throws JSONException
     */
    public Writer write(Writer writer) throws JSONException {
        return this.write(writer, 0, 0);
    }

    static final Writer writeValue(Writer writer, Object value,
            int indentFactor, int indent) throws JSONException, IOException {
        if (value == null || value.equals(null)) {
            writer.write("null");
        } else if (value instanceof JSONString) {
            Object o;
            try {
                o = ((JSONString) value).toJSONString();
            } catch (Exception e) {
                throw new JSONException(e);
            }
            writer.write(o != null ? o.toString() : quote(value.toString()));
        } else if (value instanceof Number) {
            // not all Numbers may match actual JSON Numbers. i.e. fractions or Imaginary
            final String numberAsString = numberToString((Number) value);
            if(NUMBER_PATTERN.matcher(numberAsString).matches()) {
                writer.write(numberAsString);
            } else {
                // The Number value is not a valid JSON number.
                // Instead we will quote it as a string
                quote(numberAsString, writer);
            }
        } else if (value instanceof Boolean) {
            writer.write(value.toString());
        } else if (value instanceof Enum<?>) {
            writer.write(quote(((Enum<?>)value).name()));
        } else if (value instanceof JSONObject) {
            ((JSONObject) value).write(writer, indentFactor, indent);
        } else if (value instanceof JSONArray) {
            ((JSONArray) value).write(writer, indentFactor, indent);
        } else if (value instanceof Map) {
            Map<?, ?> map = (Map<?, ?>) value;
            new JSONObject(map).write(writer, indentFactor, indent);
        } else if (value instanceof Collection) {
            Collection<?> coll = (Collection<?>) value;
            new JSONArray(coll).write(writer, indentFactor, indent);
        } else if (value.getClass().isArray()) {
            new JSONArray(value).write(writer, indentFactor, indent);
        } else {
            quote(value.toString(), writer);
        }
        return writer;
    }

    static final void indent(Writer writer, int indent) throws IOException {
        for (int i = 0; i < indent; i += 1) {
            writer.write(' ');
        }
    }

    /**
     * Write the contents of the JSONObject as JSON text to a writer.
     * 
     * <p>If <code>indentFactor > 0</code> and the {@link JSONObject}
     * has only one key, then the object will be output on a single line:
     * <pre>{@code {"key": 1}}</pre>
     * 
     * <p>If an object has 2 or more keys, then it will be output across
     * multiple lines: <code><pre>{
     *  "key1": 1,
     *  "key2": "value 2",
     *  "key3": 3
     * }</pre></code>
     * <p><b>
     * Warning: This method assumes that the data structure is acyclical.
     * </b>
     *
     * @param writer
     *            Writes the serialized JSON
     * @param indentFactor
     *            The number of spaces to add to each level of indentation.
     * @param indent
     *            The indentation of the top level.
     * @return The writer.
     * @throws JSONException
     */
    public Writer write(Writer writer, int indentFactor, int indent)
            throws JSONException {
        try {
            boolean commanate = false;
            final int length = this.length();
            writer.write('{');

            if (length == 1) {
            	final Entry<String,?> entry = this.entrySet().iterator().next();
                final String key = entry.getKey();
                writer.write(quote(key));
                writer.write(':');
                if (indentFactor > 0) {
                    writer.write(' ');
                }
                try{
                    writeValue(writer, entry.getValue(), indentFactor, indent);
                } catch (Exception e) {
                    throw new JSONException("Unable to write JSONObject value for key: " + key, e);
                }
            } else if (length != 0) {
                final int newindent = indent + indentFactor;
                for (final Entry<String,?> entry : this.entrySet()) {
                    if (commanate) {
                        writer.write(',');
                    }
                    if (indentFactor > 0) {
                        writer.write('\n');
                    }
                    indent(writer, newindent);
                    final String key = entry.getKey();
                    writer.write(quote(key));
                    writer.write(':');
                    if (indentFactor > 0) {
                        writer.write(' ');
                    }
                    try {
                        writeValue(writer, entry.getValue(), indentFactor, newindent);
                    } catch (Exception e) {
                        throw new JSONException("Unable to write JSONObject value for key: " + key, e);
                    }
                    commanate = true;
                }
                if (indentFactor > 0) {
                    writer.write('\n');
                }
                indent(writer, indent);
            }
            writer.write('}');
            return writer;
        } catch (IOException exception) {
            throw new JSONException(exception);
        }
    }

    /**
     * Returns a java.util.Map containing all of the entries in this object.
     * If an entry in the object is a JSONArray or JSONObject it will also
     * be converted.
     * <p>
     * Warning: This method assumes that the data structure is acyclical.
     *
     * @return a java.util.Map containing the entries of this object
     */
    public Map<String, Object> toMap() {
        Map<String, Object> results = new HashMap<String, Object>();
        for (Entry<String, Object> entry : this.entrySet()) {
            Object value;
            if (entry.getValue() == null || NULL.equals(entry.getValue())) {
                value = null;
            } else if (entry.getValue() instanceof JSONObject) {
                value = ((JSONObject) entry.getValue()).toMap();
            } else if (entry.getValue() instanceof JSONArray) {
                value = ((JSONArray) entry.getValue()).toList();
            } else {
                value = entry.getValue();
            }
            results.put(entry.getKey(), value);
        }
        return results;
    }
}