Reduced duplication between ConfigUtil and JsonUserPrefsStorage

src/main/java/seedu/address/MainApp.java

@@ -14,13 +14,12 @@
 import seedu.address.logic.Logic;
 import seedu.address.logic.LogicManager;
 import seedu.address.model.*;
-import seedu.address.commons.util.ConfigUtil;
+import seedu.address.storage.ConfigStorage;
 import seedu.address.storage.Storage;
 import seedu.address.storage.StorageManager;
 import seedu.address.ui.Ui;
 import seedu.address.ui.UiManager;
 
-import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.util.Map;
 import java.util.Optional;
@@ -107,7 +106,7 @@ protected Config initConfig(String configFilePath) {
         logger.info("Using config file : " + configFilePathUsed);
 
         try {
-            Optional<Config> configOptional = ConfigUtil.readConfig(configFilePathUsed);
+            Optional<Config> configOptional = ConfigStorage.readConfig(configFilePathUsed);
             initializedConfig = configOptional.orElse(new Config());
         } catch (DataConversionException e) {
             logger.warning("Config file at " + configFilePathUsed + " is not in the correct format. " +
@@ -117,7 +116,7 @@ protected Config initConfig(String configFilePath) {
 
         //Update config file in case it was missing to begin with or there are new/unused fields
         try {
-            ConfigUtil.saveConfig(initializedConfig, configFilePathUsed);
+            ConfigStorage.saveConfig(initializedConfig, configFilePathUsed);
         } catch (IOException e) {
             logger.warning("Failed to save config file : " + StringUtil.getDetails(e));
         }

src/main/java/seedu/address/commons/core/Config.java

@@ -1,12 +1,14 @@
 package seedu.address.commons.core;
 
+import seedu.address.storage.JsonFile;
+
 import java.util.Objects;
 import java.util.logging.Level;
 
 /**
  * Config values used by the app
  */
-public class Config {
+public class Config extends JsonFile {
 
     public static final String DEFAULT_CONFIG_FILE = "config.json";
 

src/main/java/seedu/address/commons/util/FileUtil.java

@@ -5,9 +5,11 @@
 import java.nio.file.Files;
 
 /**
- * Writes and reads file
+ * Writes and reads files, includes methods for reading and writing to
+ * preference/config json files
  */
 public class FileUtil {
+
     private static final String CHARSET = "UTF-8";
 
     public static boolean isFileExists(File file) {
@@ -84,12 +86,4 @@ public static String getPath(String pathWithForwardSlash) {
         return pathWithForwardSlash.replace("/", File.separator);
     }
 
-    public static <T> void serializeObjectToJsonFile(File jsonFile, T objectToSerialize) throws IOException {
-        FileUtil.writeToFile(jsonFile, JsonUtil.toJsonString(objectToSerialize));
-    }
-
-    public static <T> T deserializeObjectFromJsonFile(File jsonFile, Class<T> classOfObjectToDeserialize)
-            throws IOException {
-        return JsonUtil.fromJsonString(FileUtil.readFromFile(jsonFile), classOfObjectToDeserialize);
-    }
 }

src/main/java/seedu/address/commons/util/JsonUtil.java

@@ -10,14 +10,77 @@
 import com.fasterxml.jackson.databind.deser.std.FromStringDeserializer;
 import com.fasterxml.jackson.databind.module.SimpleModule;
 import com.fasterxml.jackson.databind.ser.std.ToStringSerializer;
+import seedu.address.commons.core.LogsCenter;
+import seedu.address.commons.exceptions.DataConversionException;
+import seedu.address.storage.JsonFile;
 
+import java.io.File;
 import java.io.IOException;
+import java.util.Optional;
 import java.util.logging.Level;
+import java.util.logging.Logger;
 
 /**
  * Converts a Java object instance to JSON and vice versa
  */
 public class JsonUtil {
+
+    private static final Logger logger = LogsCenter.getLogger(JsonUtil.class);
+
+    public static <T> void serializeObjectToJsonFile(File jsonFile, T objectToSerialize) throws IOException {
+        FileUtil.writeToFile(jsonFile, toJsonString(objectToSerialize));
+    }
+
+    public static <T> T deserializeObjectFromJsonFile(File jsonFile, Class<T> classOfObjectToDeserialize)
+            throws IOException {
+        return fromJsonString(FileUtil.readFromFile(jsonFile), classOfObjectToDeserialize);
+    }
+
+    /**
+     * Returns the Json object from the given file or {@code Optional.empty()} object if the file is not found.
+     * If any values are missing from the file, default values will be used, as long as the file is a valid json file.
+     * @param filePath cannot be null.
+     * @param classOfObjectToDeserialize has to extend JsonFile.
+     * @throws DataConversionException if the file format is not as expected.
+     */
+    public static <T extends JsonFile> Optional<T> readJsonFile(
+            String filePath, Class<T> classOfObjectToDeserialize) throws DataConversionException {
+
+        assert filePath != null;
+
+        File file = new File(filePath);
+
+        if (!file.exists()) {
+            logger.info("Config file "  + file + " not found");
+            return Optional.empty();
+        }
+
+        T jsonFile;
+
+        try {
+            jsonFile = deserializeObjectFromJsonFile(file, classOfObjectToDeserialize);
+        } catch (IOException e) {
+            logger.warning("Error reading from jsonFile file " + file + ": " + e);
+            throw new DataConversionException(e);
+        }
+
+        return Optional.of(jsonFile);
+    }
+
+    /**
+     * Saves the Json object to the specified file.
+     * Overwrites existing file if it exists, creates a new file if it doesn't.
+     * @param jsonFile cannot be null
+     * @param filePath cannot be null
+     * @throws IOException if there was an error during writing to the file
+     */
+    public static <T extends JsonFile> void saveJsonFile(T jsonFile, String filePath) throws IOException {
+        assert jsonFile != null;
+        assert filePath != null;
+
+        serializeObjectToJsonFile(new File(filePath), jsonFile);
+    }
+
     private static class LevelDeserializer extends FromStringDeserializer<Level> {
 
         protected LevelDeserializer(Class<?> vc) {

src/main/java/seedu/address/model/UserPrefs.java

@@ -1,13 +1,14 @@
 package seedu.address.model;
 
 import seedu.address.commons.core.GuiSettings;
+import seedu.address.storage.JsonFile;
 
 import java.util.Objects;
 
 /**
  * Represents User's preferences.
  */
-public class UserPrefs {
+public class UserPrefs extends JsonFile {
 
     public GuiSettings guiSettings;
 

src/main/java/seedu/address/storage/ConfigStorage.java

@@ -0,0 +1,23 @@
+package seedu.address.storage;
+
+import seedu.address.commons.core.Config;
+import seedu.address.commons.exceptions.DataConversionException;
+import seedu.address.commons.util.JsonUtil;
+
+import java.io.IOException;
+import java.util.Optional;
+
+/**
+ * A class for accessing the Config File.
+ */
+public class ConfigStorage {
+
+    public static Optional<Config> readConfig(String configFilePath) throws DataConversionException {
+        return JsonUtil.readJsonFile(configFilePath, Config.class);
+    }
+
+    public static void saveConfig(Config config, String configFilePath) throws IOException {
+        JsonUtil.saveJsonFile(config, configFilePath);
+    }
+
+}

src/main/java/seedu/address/storage/JsonFile.java

@@ -0,0 +1,14 @@
+package seedu.address.storage;
+
+/**
+ * Purely a marker for FileUtil.
+ */
+public abstract class JsonFile {
+
+    public abstract boolean equals(Object other);
+
+    public abstract int hashCode();
+
+    public abstract String toString();
+
+}

src/main/java/seedu/address/storage/JsonUserPrefsStorage.java

@@ -1,22 +1,17 @@
 package seedu.address.storage;
 
-import seedu.address.commons.core.LogsCenter;
 import seedu.address.commons.exceptions.DataConversionException;
-import seedu.address.commons.util.FileUtil;
+import seedu.address.commons.util.JsonUtil;
 import seedu.address.model.UserPrefs;
 
-import java.io.File;
 import java.io.IOException;
 import java.util.Optional;
-import java.util.logging.Logger;
 
 /**
  * A class to access UserPrefs stored in the hard disk as a json file
  */
 public class JsonUserPrefsStorage implements UserPrefsStorage{
 
-    private static final Logger logger = LogsCenter.getLogger(JsonUserPrefsStorage.class);
-
     private String filePath;
 
     public JsonUserPrefsStorage(String filePath){
@@ -28,46 +23,13 @@ public Optional<UserPrefs> readUserPrefs() throws DataConversionException, IOExc
         return readUserPrefs(filePath);
     }
 
-    @Override
-    public void saveUserPrefs(UserPrefs userPrefs) throws IOException {
-        saveUserPrefs(userPrefs, filePath);
-    }
-
-    /**
-     * Similar to {@link #readUserPrefs()}
-     * @param prefsFilePath location of the data. Cannot be null.
-     * @throws DataConversionException if the file format is not as expected.
-     */
     public Optional<UserPrefs> readUserPrefs(String prefsFilePath) throws DataConversionException {
-        assert prefsFilePath != null;
-
-        File prefsFile = new File(prefsFilePath);
-
-        if (!prefsFile.exists()) {
-            logger.info("Prefs file "  + prefsFile + " not found");
-            return Optional.empty();
-        }
-
-        UserPrefs prefs;
-
-        try {
-            prefs = FileUtil.deserializeObjectFromJsonFile(prefsFile, UserPrefs.class);
-        } catch (IOException e) {
-            logger.warning("Error reading from prefs file " + prefsFile + ": " + e);
-            throw new DataConversionException(e);
-        }
-
-        return Optional.of(prefs);
+        return JsonUtil.readJsonFile(prefsFilePath, UserPrefs.class);
     }
 
-    /**
-     * Similar to {@link #saveUserPrefs(UserPrefs)}
-     * @param prefsFilePath location of the data. Cannot be null.
-     */
-    public void saveUserPrefs(UserPrefs userPrefs, String prefsFilePath) throws IOException {
-        assert userPrefs != null;
-        assert prefsFilePath != null;
-
-        FileUtil.serializeObjectToJsonFile(new File(prefsFilePath), userPrefs);
+    @Override
+    public void saveUserPrefs(UserPrefs userPrefs) throws IOException {
+        JsonUtil.saveJsonFile(userPrefs, filePath);
     }
+
 }

src/test/java/seedu/address/commons/util/FileUtilTest.java

@@ -4,17 +4,12 @@
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.ExpectedException;
-import seedu.address.testutil.SerializableTestClass;
-import seedu.address.testutil.TestUtil;
 
 import java.io.File;
-import java.io.IOException;
 
 import static org.junit.Assert.assertEquals;
 
 public class FileUtilTest {
-    private static final File SERIALIZATION_FILE = new File(TestUtil.getFilePathInSandboxFolder("serialize.json"));
-
 
     @Rule
     public ExpectedException thrown = ExpectedException.none();
@@ -34,25 +29,4 @@ public void getPath(){
         FileUtil.getPath("folder");
     }
 
-    @Test
-    public void serializeObjectToJsonFile_noExceptionThrown() throws IOException {
-        SerializableTestClass serializableTestClass = new SerializableTestClass();
-        serializableTestClass.setTestValues();
-
-        FileUtil.serializeObjectToJsonFile(SERIALIZATION_FILE, serializableTestClass);
-
-        assertEquals(FileUtil.readFromFile(SERIALIZATION_FILE), SerializableTestClass.JSON_STRING_REPRESENTATION);
-    }
-
-    @Test
-    public void deserializeObjectFromJsonFile_noExceptionThrown() throws IOException {
-        FileUtil.writeToFile(SERIALIZATION_FILE, SerializableTestClass.JSON_STRING_REPRESENTATION);
-
-        SerializableTestClass serializableTestClass = FileUtil
-                .deserializeObjectFromJsonFile(SERIALIZATION_FILE, SerializableTestClass.class);
-
-        assertEquals(serializableTestClass.getName(), SerializableTestClass.getNameTestValue());
-        assertEquals(serializableTestClass.getListOfLocalDateTimes(), SerializableTestClass.getListTestValues());
-        assertEquals(serializableTestClass.getMapOfIntegerToString(), SerializableTestClass.getHashMapTestValues());
-    }
 }