Fragment restarts when orientation is changed

Question

I have this Hierarchy in my android app

Activity contains the FragmentGame fragment, that contains the FragmentTypeOfGame;

Activity >> FragmentGame >> FragmentTypeOfGame

Inside FragmentGame, i got a timer and another labels, so, when I change the screen orientation, my game seems restarted, but i can check the timer keeps running (because it`s another thread, I guess).

So my question is, how can I manage to keep all screen running without restarting.

I have already seem these links, but i can't find out how to solve it?

Why not use always android:configChanges="keyboardHidden|orientation"?

Forcing Android to not redraw activity on orientation change

Here goes my manifest:

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme"
    >
    <meta-data android:name="com.facebook.sdk.ApplicationId" android:value="@string/facebook_app_id"/>
    <activity
        android:name=".MainActivity"
        android:label="@string/app_name"
        android:configChanges="orientation"
        >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

    <activity android:name="com.facebook.FacebookActivity"
        android:configChanges=
            "keyboard|keyboardHidden|screenLayout|screenSize|orientation"
        android:theme="@android:style/Theme.Translucent.NoTitleBar"
        android:label="@string/app_name" />

    <provider android:authorities="com.facebook.app.FacebookContentProviderXXXXXXXXX"
        android:name="com.facebook.FacebookContentProvider"
        android:exported="true" />
</application>

Here my GameFragment OnCreateView:

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

    //Default components start
    defaultComponentsStarting(inflater, container);

    FourBlocksGameStyle f = new FourBlocksGameStyle();
    frgManager.beginTransaction().replace(R.id.rl_root, f, "4blocks").addToBackStack(null).commit();

    if (savedInstanceState != null) {
        // Restore last state
        actualGameTime = savedInstanceState.getDouble("actualGameTime");
    }

    handler = new Handler(Looper.getMainLooper());
    mainRunnable = new Runnable() {
        @Override
        public void run() {
            // Do something and reschedule ourself

            if(GAMETIME <= actualGameTime){
                cancelTimer();

                setLabel(txtTimer, 0, GAMETIME / 1000);
                int countSum = Integer.parseInt(txtHits.getText().toString());

                //Devolve pra main cuidar da finalização
                Intent i = new Intent(ctx, MainActivity.class);
                i.putExtra("CountSum", countSum);
                startActivity(i);
            }
            else {
                actualGameTime += GAMEDELAY;
                double floatingTime = actualGameTime / 1000;

                setLabel(txtTimer, 0, floatingTime);
                handler.postDelayed(this, GAMEDELAY);
            }
        }
    };
    return view;
}

and here my MainActivity onCreate?

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    FacebookSdk.sdkInitialize(getApplicationContext());
    setContentView(R.layout.activity_main);

    this.setVolumeControlStream(AudioManager.STREAM_MUSIC);

    final SharedPreferences prefs = getSharedPreferences("hitColor", MODE_PRIVATE);
    int startHighscore = prefs.getInt("highScore", 0);

    gameOver = new GameOverFragment();
    highScoreGameOver = new HighScoreFragment();
    game = new GameFragment();

    Intent i = getIntent();
    int countSum = i.getIntExtra("CountSum", -1);

    if(countSum == -1) {
        //Log.d("GSS", "Primeira entrada");
        if(savedInstanceState == null) {
            Log.d("GSS", "savedInstace null");
            getFragmentManager()
                    .beginTransaction()
                    .replace(R.id.layout_root_view, game)
                    .addToBackStack(null)
                    .commit();
        }
    }
    else {
        Log.d("GSS", "COUNT: " + String.valueOf(countSum));
        Log.d("GSS", "HIGH: " + String.valueOf(startHighscore));

        finishGame(countSum, startHighscore, prefs);
    }
}

Answer 1

here is example how you can get the data from Fragment manually..

public class RetainedFragment extends Fragment {

// data object we want to retain
private MyDataObject data;

// this method is only called once for this fragment
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    // retain this fragment
    setRetainInstance(true);
}

public void setData(MyDataObject data) {
    this.data = data;
}

public MyDataObject getData() {
    return data;
}
 public Bitmap getBitmap() { return bitmap; }
 public void setBitmap(Bitmap bmp) { bitmap = bmp; }
}

then in your MainActivity, you get the data when the fragment restarts,

public class MyActivity extends Activity {

private RetainedFragment dataFragment;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    // find the retained fragment on activity restarts
    FragmentManager fm = getFragmentManager();
    dataFragment = (DataFragment) fm.findFragmentByTag(“data”);

    // create the fragment and data the first time
    if (dataFragment == null) {
        // add the fragment
        dataFragment = new DataFragment();
        fm.beginTransaction().add(dataFragment, “data”).commit();
        // load the data from the web
        dataFragment.setData(loadMyData());
    }

    // the data is available in dataFragment.getData()
    ...
}

@Override
public void onDestroy() {
    super.onDestroy();
    // store the data in the fragment
    dataFragment.setData(collectMyLoadedData());
}
}

still, you can restore the Object, but you should never pass an object that is tied to the Activity, such as a Drawable, an Adapter, a View or any other object that's associated with a Context. hope this helps ..

Also, you can set the restoration in the following method,

@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);

// Checks the orientation of the screen
if (newConfig.orientation == Configuration.ORIENTATION_LANDSCAPE) {
    Toast.makeText(this, "landscape", Toast.LENGTH_SHORT).show();
     // code for landscape configurtion // load the previous data.
} else if (newConfig.orientation == Configuration.ORIENTATION_PORTRAIT){
    Toast.makeText(this, "portrait", Toast.LENGTH_SHORT).show();
    // code for landscape configurtion // load the previous data.
}
}

Answer 2

With your current configuration for activity's configChanges, Your Fragment will recreate the UI when you change the Orientation. Since it will be totally new layout, it makes sense.

But your Fragment won't be calling onCreate again. It will start from onCreateView after calling onPause and onStop to destroy the Fragment's UI.

So when the Orientation Changes, meaning when the Fragment goes to onPause, you should save your UI data in a Bundle object (define it as a global variable inside the Fragment) in onPause. Since the Fragment will start from onCreateView you can restore your UI data after inflating your Layout in onCreateView method.

Bundle savedInstanceState will be null. It won't store your data when the configuration changes, so you cannot rely on that.