Local broadcast receiver used as observer in loader

app/src/main/java/com/philliphsu/clock2/model/AlarmDatabaseHelper.java

@@ -9,6 +9,7 @@ import android.database.sqlite.SQLiteOpenHelper;
 import android.util.Log;
 
 import com.philliphsu.clock2.Alarm;
+import com.philliphsu.clock2.util.LocalBroadcastHelper;
 
 import static com.philliphsu.clock2.DaysOfWeek.FRIDAY;
 import static com.philliphsu.clock2.DaysOfWeek.MONDAY;
@@ -65,8 +66,13 @@ public class AlarmDatabaseHelper extends SQLiteOpenHelper {
     private static final String SORT_ORDER =
             COLUMN_RING_TIME_MILLIS + " ASC, " + COLUMN_ID + " ASC";
 
+    private final Context mAppContext;
+
     public AlarmDatabaseHelper(Context context) {
         super(context, DB_NAME, null, VERSION_1);
+        // Since DatabaseManager calls this with the application
+        // context, we can safely hold onto this context.
+        mAppContext = context;
     }
 
     @Override
@@ -105,6 +111,7 @@ public class AlarmDatabaseHelper extends SQLiteOpenHelper {
         long id = getWritableDatabase().insert(TABLE_ALARMS,
                 null, toContentValues(alarm));
         alarm.setId(id);
+        notifyContentChanged();
         return id;
     }
 
@@ -115,26 +122,32 @@ public class AlarmDatabaseHelper extends SQLiteOpenHelper {
     public int updateAlarm(Alarm oldAlarm, Alarm newAlarm) {
         newAlarm.setId(oldAlarm.id());
         SQLiteDatabase db = getWritableDatabase();
-        return db.update(TABLE_ALARMS,
+        int rowsUpdated = db.update(TABLE_ALARMS,
                 toContentValues(newAlarm),
                 COLUMN_ID + " = " + newAlarm.id(),
                 null);
+        notifyContentChanged();
+        return rowsUpdated;
     }
 
     public int updateAlarm(long id, Alarm newAlarm) {
         newAlarm.setId(id);
         SQLiteDatabase db = getWritableDatabase();
-        return db.update(TABLE_ALARMS,
+        int rowsUpdated = db.update(TABLE_ALARMS,
                 toContentValues(newAlarm),
                 COLUMN_ID + " = " + id,
                 null);
+        notifyContentChanged();
+        return rowsUpdated;
     }
 
     public int deleteAlarm(Alarm alarm) {
         SQLiteDatabase db = getWritableDatabase();
-        return db.delete(TABLE_ALARMS,
+        int rowsDeleted = db.delete(TABLE_ALARMS,
                 COLUMN_ID + " = " + alarm.id(),
                 null);
+        notifyContentChanged();
+        return rowsDeleted;
     }
 
     public AlarmCursor queryAlarm(long id) {
@@ -184,6 +197,12 @@ public class AlarmDatabaseHelper extends SQLiteOpenHelper {
         return values;
     }
 
+    private void notifyContentChanged() {
+        Log.d(TAG, "notifyContentChanged()");
+        LocalBroadcastHelper.sendBroadcast(mAppContext,
+                SQLiteCursorLoader.ACTION_CHANGE_CONTENT);
+    }
+
     // An alternative method to creating an Alarm from a cursor is to
     // make an Alarm constructor that takes an Cursor param. However,
     // this method has the advantage of keeping all the constants

app/src/main/java/com/philliphsu/clock2/model/SQLiteCursorLoader.java

@@ -1,8 +1,13 @@
 package com.philliphsu.clock2.model;
 
+import android.content.BroadcastReceiver;
 import android.content.Context;
+import android.content.Intent;
 import android.database.Cursor;
 import android.support.v4.content.AsyncTaskLoader;
+import android.util.Log;
+
+import com.philliphsu.clock2.util.LocalBroadcastHelper;
 
 /**
  * Created by Phillip Hsu on 6/28/2016.
@@ -12,7 +17,10 @@ import android.support.v4.content.AsyncTaskLoader;
 public abstract class SQLiteCursorLoader extends AsyncTaskLoader<Cursor> {
     private static final String TAG = "SQLiteCursorLoader";
 
+    public static final String ACTION_CHANGE_CONTENT = "com.philliphsu.clock2.model.action.CHANGE_CONTENT";
+
     private Cursor mCursor;
+    private OnContentChangeReceiver mOnContentChangeReceiver;
 
     public SQLiteCursorLoader(Context context) {
         super(context);
@@ -66,30 +74,54 @@ public abstract class SQLiteCursorLoader extends AsyncTaskLoader<Cursor> {
         if (mCursor != null) {
             deliverResult(mCursor);
         }
+
+        if (mOnContentChangeReceiver == null) {
+            mOnContentChangeReceiver = new OnContentChangeReceiver();
+            LocalBroadcastHelper.registerReceiver(getContext(),
+                    mOnContentChangeReceiver, ACTION_CHANGE_CONTENT);
+        }
+
         if (takeContentChanged() || mCursor == null) {
             forceLoad();
         }
     }
+
     @Override
     protected void onStopLoading() {
         // Attempt to cancel the current load task if possible.
         cancelLoad();
     }
+
     @Override
     public void onCanceled(Cursor cursor) {
         if (cursor != null && !cursor.isClosed()) {
             cursor.close();
         }
     }
+
     @Override
     protected void onReset() {
         super.onReset();
         // Ensure the loader is stopped
         onStopLoading();
+
         if (mCursor != null && !mCursor.isClosed()) {
             mCursor.close();
         }
         mCursor = null;
+
+        if (mOnContentChangeReceiver != null) {
+            LocalBroadcastHelper.unregisterReceiver(getContext(),
+                    mOnContentChangeReceiver);
+            mOnContentChangeReceiver = null;
+        }
     }
 
+    private final class OnContentChangeReceiver extends BroadcastReceiver {
+        @Override
+        public void onReceive(Context context, Intent intent) {
+            Log.d(TAG, "Received content change event");
+            onContentChanged();
+        }
+    }
 }