Merge pull request #25 from Yarikx/shared-preferences-observable

Add fromSharedPreferencesChanges Observable

src/main/java/rx/android/observables/AndroidObservable.java

@@ -17,6 +17,7 @@
 
 import static rx.android.schedulers.AndroidSchedulers.mainThread;
 
+import android.content.SharedPreferences;
 import rx.Observable;
 import rx.functions.Func1;
 import rx.android.operators.OperatorBroadcastRegister;
@@ -30,6 +31,7 @@
 import android.content.IntentFilter;
 import android.os.Build;
 import android.os.Handler;
+import rx.operators.OperatorSharedPreferenceChange;
 
 
 public final class AndroidObservable {
@@ -150,4 +152,13 @@ public static Observable<Intent> fromBroadcast(Context context, IntentFilter fil
     public static Observable<Intent> fromLocalBroadcast(Context context, IntentFilter filter){
         return Observable.create(new OperatorLocalBroadcastRegister(context, filter));
     }
+
+    /**
+     * Create Observable that emits String keys whenever it changes in provided SharedPreferences
+     *
+     * Items will be observed on the main Android UI thread
+     */
+    public static Observable<String> fromSharedPreferencesChanges(SharedPreferences sharedPreferences){
+        return Observable.create(new OperatorSharedPreferenceChange(sharedPreferences));
+    }
 }

src/main/java/rx/operators/OperatorSharedPreferenceChange.java

@@ -0,0 +1,50 @@
+/**
+ * Copyright 2014 Netflix, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package rx.operators;
+
+import android.content.SharedPreferences;
+import rx.Observable;
+import rx.Subscriber;
+import rx.functions.Action0;
+import rx.subscriptions.Subscriptions;
+
+public class OperatorSharedPreferenceChange implements Observable.OnSubscribe<String>{
+
+    private final SharedPreferences sharedPreferences;
+
+    public OperatorSharedPreferenceChange(SharedPreferences sharedPreferences) {
+        this.sharedPreferences = sharedPreferences;
+    }
+
+    @Override
+    public void call(final Subscriber<? super String> subscriber) {
+        final SharedPreferences.OnSharedPreferenceChangeListener listener = new SharedPreferences.OnSharedPreferenceChangeListener() {
+            @Override
+            public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
+                subscriber.onNext(key);
+            }
+        };
+
+        subscriber.add(Subscriptions.create(new Action0() {
+            @Override
+            public void call() {
+                sharedPreferences.unregisterOnSharedPreferenceChangeListener(listener);
+            }
+        }));
+
+        sharedPreferences.registerOnSharedPreferenceChangeListener(listener);
+    }
+}

src/test/java/rx/android/operators/OperatorSharedPreferencesChangeTest.java

@@ -0,0 +1,64 @@
+/**
+ * Copyright 2014 Netflix, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package rx.android.operators;
+
+import android.app.Application;
+import android.content.SharedPreferences;
+import android.preference.PreferenceManager;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.InOrder;
+import org.robolectric.Robolectric;
+import org.robolectric.RobolectricTestRunner;
+import rx.Observable;
+import rx.Observer;
+import rx.Subscription;
+import rx.android.observables.AndroidObservable;
+import rx.observers.TestObserver;
+
+import static org.mockito.Matchers.any;
+import static org.mockito.Mockito.*;
+
+@RunWith(RobolectricTestRunner.class)
+public class OperatorSharedPreferencesChangeTest {
+
+    @Test
+    public void testSharedPreferences() {
+        Application application = Robolectric.application;
+        SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(application);
+        Observable<String> observable = AndroidObservable.fromSharedPreferencesChanges(sharedPreferences);
+        final Observer<String> observer = mock(Observer.class);
+        final Subscription subscription = observable.subscribe(new TestObserver<String>(observer));
+
+        final InOrder inOrder = inOrder(observer);
+
+        inOrder.verify(observer, never()).onNext(any(String.class));
+
+        sharedPreferences.edit().putBoolean("a", true).commit();
+        inOrder.verify(observer, times(1)).onNext("a");
+
+        sharedPreferences.edit().putInt("b", 9).commit();
+        inOrder.verify(observer, times(1)).onNext("b");
+
+        subscription.unsubscribe();
+
+        sharedPreferences.edit().putInt("c", 42).commit();
+        inOrder.verify(observer, never()).onNext(any(String.class));
+        inOrder.verify(observer, never()).onError(any(Throwable.class));
+        inOrder.verify(observer, never()).onCompleted();
+    }
+
+}