Question

I need to act differently in onStart() method depending on how onCreate() was called in result
of orientation change or not. Is that possible to check it?

Actually what I need is to do something when activity starts except a case when user changes orientation.

I need to clearly distinguish cases when user just switched to another application and returned back OR he changed device’s orientation.

Answer 1

public class MyActivity extends Activity {
    boolean fromOrientation=false;
    SharedPreferences myPrefLogin;
    Editor prefsEditor;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        prefsEditor = myPrefLogin.edit();
        myPrefLogin = this.getSharedPreferences("myPrefs", Context.MODE_WORLD_READABLE);
        fromOrientation = myPrefLogin.getString("fromOrient", false);

        if(fromOrientation) {
             // do as per need--- logic of orientation changed.
        } else {
             // do as per need--- logic of default onCreate().
        }
    }

    @Override
    public Object onRetainNonConfigurationInstance() {
        prefsEditor.putString("fromOrient", true);
        prefsEditor.commit();
        return null;
    }

    @Override
    protected void onDestroy() {
        if(fromOrientation) {
            prefsEditor.putString("fromOrient", false);
            prefsEditor.commit();
        }
        super.onDestroy();
    }  
}

flag fromOrientation(tells the state either configuration had been change or not)
above we had done like by defalut we are considering that onCreate() is not called from by changing orientation. If orientation changed(onRetainNonConfigurationInstance()) then we set the flag value in preference which let us know whether onCreate() is called from on orientation or not.
And finally onDestroy() we again reset the orientation flag.