Detect if the application is manually closed or not

Question

I've written an android app which checks the network status by using a BroadcastReceiver inherited class:

public class NetworkChangeReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(final Context context, final Intent intent) {
        Log.d("mylog", "NetworkChangeReceiver Hit");
    }
}

which is registered in the manifest file like this:

<receiver
    android:name="foo.NetworkChangeReceiver"
    android:label="NetworkChangeReceiver" >
    <intent-filter>
        <action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
        <action android:name="android.net.wifi.WIFI_STATE_CHANGED" />
    </intent-filter>
</receiver>

I needed to handle the internet connection whenever it connects or disconnects. Actually, it works perfectly in normal situations.

But the problem is that when the application is closed manually (by minimizing the app and then closing it by swiping out the app icon in the Recents button menu), it still receives the network status changes. This sometimes causes some exceptions.

Even I have included all the code in receiver function in try/catch block, but still sometimes a toast message containing an error message is shown. This sometimes happen even after some days after the closure of the app.

Please note that the code in the receiver function is more complicated than the code that is shown here and has some access to internal classes and variables.

Answer 1

Your app will still receive events, even if it isn't running. Before you do anything in onReceive(), you can check if the activity is running by:

Option 1: Use a static variable in your activity to check it's state for access from the receiver :

public class YourActivity extends Activity {


 public static boolean isRunning = false;

 @Overrride
 public void onCreate(Bundle savedInstanceState){
 isRunning = true;
  ....
 }
   //We need receiver to work when app is minimized
   /*
      @Override
      public void onStart() {
         super.onStart();
         isRunning = true;
      } 


      @Override
      public void onStop() {
         super.onStop();
         isRunning = false;
      }
*/

}

And in the receiver:

public class NetworkChangeReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(final Context context, final Intent intent) {
        Log.d("mylog", "NetworkChangeReceiver Hit");
            if(!YourActivity.isRunning)
              return;
    }
}

Option 2 : Using the ActivityManager

public class NetworkChangeReceiver extends BroadcastReceiver {
@Override
public void onReceive(final Context context, final Intent intent) {

    if (isAppForground(context)) 
         return;

}

public boolean isAppForground(Context mContext) {

    ActivityManager am = (ActivityManager) mContext.getSystemService(Context.ACTIVITY_SERVICE);
    List<RunningTaskInfo> tasks = am.getRunningTasks(1);
    if (!tasks.isEmpty()) {
        ComponentName topActivity = tasks.get(0).topActivity;
        if (!topActivity.getPackageName().equals(mContext.getPackageName())) {
            return false;
        }
    }

    return true;
}

}

You'll need the permission:

<uses-permission android:name="android.permission.GET_TASKS" />

Answer 2

If you define receivers in your manifest, the app will receive events, even if it is not started.

http://developer.android.com/guide/topics/manifest/receiver-element.html

Broadcast receivers enable applications to receive intents that are broadcast by the system or by other applications, even when other components of the application are not running.

To fix this, just don't define the Receiver in the manifest, but do it programatically in onStart and unregister it again in onStop. The problem with this solution is, that you won't get messages if your app is in the background.

private BroadcastReceiver receiver;

@Overrride
public void onStart(){

   super.onStart();

   IntentFilter filter = new IntentFilter();
   filter.addAction("android.net.conn.CONNECTIVITY_CHANGE");
   filter.addAction("android.net.wifi.WIFI_STATE_CHANGED");

   receiver = new NetworkChangeReceiver();
   registerReceiver(receiver, filter);
}

@Override
protected void onStop() {
   super.onStop();
   //don't forget to unregister the receiver again
   unregisterReceiver(receiver);
}

EDIT: onCreate and onDestroy won't work, as onDestroy will not be called in every instance the app is closed (e.g. if it is closed with the task manager)

Answer 3

Solution Found:

I found a perfect solution to my problem. Thanks to the correct answer in Android service crashes after app is swiped out of the recent apps list, I found out that when an app is closed via Recents list, the whole process will be created again and all the static variables will be freshed to their default values, and the onCreate and all other methods will not be called. So the solution is something like:

public static boolean appStarted = false;
protected void onCreate(Bundle savedInstanceState) {
    appStarted = true;
    ...
}


public class NetworkChangeReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(final Context context, final Intent intent) {
        if (!MyActivity.appStarted)
            return;
        ...
    }
}

The key is to just keep track of when the app starts, and not when the app is closed (because the closing event of app is not dependable and in some situations doesn't work properly)