Which activity method is called when orientation changes occur?

Question

Which method of the lifecycle is called when orientation changes occur? My application executes the onResume() method or maybe reloads the whole activity because I've set one boolean to check whether it is first run or not. I've read onConfigurationChanged() starts when orientation change occur, is it true? How to handle this?

Trishatriskelion

developer.android.com/reference/android/app/… – Consciencestricken

If i add android:configChanges="orientation", the whole activity will not be restarted, but onConfigurationChanged() will be called instead? – Trishatriskelion

Remember that you can have separate layouts for portrait and landscape - then your activity needs to be recreated/reinflated. – Consciencestricken

@Marcin Gil I have a map and i have draw graphics on the users location, but when orientation occurs then the graphics is removed. I want to keep this. I have created reDraw() method which redraws the location, but the app restarts the whole activity... – Trishatriskelion

See here: developer.android.com/resources/articles/… – Consciencestricken

Answer 1

Interesting one...

Activity is start onResume() is which you declare in your XML by default.

And as I found from question answer on stack overflow is:

Orientation Change

• onSaveInstanceState
• onPause
• onStop
• onCreate
• onStart
• onRestoreInstanceState
• onResume

Switch TO Activity 2

• onSaveInstanceState
• onPause

Orientation Change WHILE IN Activity 2

• onStop
• onCreate
• onStart

Switchback BACK FROM Activity2

• onResume

I'm guessing that because Activity 1 is hidden at the time of rotation, onRestoreInstanceState isn't called because there is no 'view' (i.e., it can't be seen/viewed). Also, it is entirely possible to have 2 completely different layout files for portrait/landscape which potentially have different UI elements with different IDs.

As a result, I'd say if you want to use the Bundle in onSaveInstanceState to save your own data, then you need to add extra logic in your onCreate (in Activity 1) to process your own data there (as well as doing it conditionally in onRestoreInstanceState).

In particular, you could maintain a 'last known' orientation field so that onCreate knows that it needs to process your own data because orientation has changed, rather than relying on onRestoreInstanceState being called.

Gigolo

Actually Orientation change = onPause -> onSave... -> onStop -> onCreate -> onStart -> onResume – Nikolaos

Yep, in all cases onPause goes first, then onSaveInstanceState – Antananarivo

According to android documents, no one can anticipate whether onSaveInstanceState will be called before or after onPause. We can only say with surety that onSaveInstanceState is called after onStop developer.android.com/reference/android/app/… – Topsoil

^^ that's not correct. We can only say that onSaveInstanceState is called BEFORE onStop -> "If called, this method will occur before onStop(). There are no guarantees about whether it will occur before or after onPause()." – Guanajuato

in my case onDestroy is also getting called on rotation – Calicle

Orientation change = onPause() -> onSaveInstanceState() -> onStop() -> onDestroy() -> onCreate() -> onStart() -> onRestoreInstanceState() -> onResume() – Midweek

Answer 2

public class MainActivity extends AppCompatActivity {
private final static String TAG = "AppActivity";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    Log.d(TAG, "onCreate(Bundle) called");
    setContentView(R.layout.activity_main);
}

@Override
public void onStart() {
    super.onStart();
    Log.d(TAG, "onStart() called");
}

@Override
public void onPause() {
    super.onPause();
    Log.d(TAG, "onPause() called");
}

@Override
public void onResume() {
    super.onResume();
    Log.d(TAG, "onResume() called");
}

@Override
public void onStop() {
    super.onStop();
    Log.d(TAG, "onStop() called");
}

@Override
public void onDestroy() {
    super.onDestroy();
    Log.d(TAG, "onDestroy() called");
}

}

1) Try to run your app on your phone and/or emulator and open the Logcat => on top of the window select Verbose.

2) Now try to change the screen orientation (ex. from portrait => landscape mode).

I hope this alternative will give you more insight into the activity lifecycle.

Dirham