Why is my activity restarted despite all my efforts

Question

This is not a question of how I can avoid my activity restart and recreation on say config changes lie e.t.c This is a question of why, despite all my efforts, my activity still restarts.What could be the possible reason?

Here is my scenario.

My app a text editing application, with tabs, so I implemented a custom TabHost and a custom TabWidget. The app has the MainActivity and a single fragment, MainFragment.

On To ensure instance is retained in my MainFragment, I have these:

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setRetainInstance(true);
    setHasOptionsMenu(true);
}

@Override
public void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);

}

To ensure MainActivity instance is retained, I have this:

/**
 * @see android.app.Activity#onCreate(android.os.Bundle)
 */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    FrameLayout frame = new FrameLayout(this);
    frame.setId(android.R.id.content);
    setContentView(frame, new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
    actionBar = getSupportActionBar();
    if ((MyTextEditor.isSmallScreenSize(getResources()) || MyTextEditor.isNormalScreenSize(getResources())) 
            && getResources().getConfiguration().orientation == Configuration.ORIENTATION_PORTRAIT ) {
        actionBar.setDisplayShowTitleEnabled(false);
    }
    if (savedInstanceState != null) {
        editorFrag = (MyTedFragment) getSupportFragmentManager().getFragment(
                savedInstanceState, "editor");
    }
    if (editorFrag == null) {
        editorFrag = new MyTedFragment();
        getSupportFragmentManager().beginTransaction()
        .replace(android.R.id.content, editorFrag).commit();
    }
         ....
}
     @Override
protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    getSupportFragmentManager().putFragment(outState, "editor", editorFrag);
}

And the following in my AndroidManifest.xml

<application
    android:name="com.myapp.MyApp"
    android:debuggable="true"
    android:hardwareAccelerated="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/MyAppTheme" >

    <!-- Ted main activity ... ie a text field :)
     android:uiOptions="splitActionBarWhenNarrow" 
     android:windowSoftInputMode="adjustResize"
     android:configChanges="mcc|mnc|locale|touchscreen|keyboard|keyboardHidden|navigation|orientation|screenLayout|uiMode|fontScale|screenSize|smallestScreenSize">

  -->
    <activity
        android:name="com.myapp.texteditor.MainActivity"
         android:configChanges="mcc|mnc|locale|touchscreen|keyboard|keyboardHidden|navigation|orientation|screenLayout|uiMode|fontScale|screenSize|smallestScreenSize"
        android:launchMode="singleTask" android:windowSoftInputMode="adjustResize">

   </activity>
    ....
   </application>

Now the problem:

CASE 1: Android version: 2.3.6 Gingerbread on Samsung device

If I push my activity to the background and I relaunch my app in less than about 3 minutes , the main activity instance is restored just fine. If I choose to relaunch my app after a while longer, say 10 min or so,the app restarts afresh and this is bad for my app because if a user had any unsaved changes, they are lost.

CASE 2: Android Version: 4.3, running on Emulator

How long I choose to wait before relaunching the app, the instance is always restored. Looks like everything works fine.

What could be the reason for this? Is this associated with a bug around the activity life cycle or Activity Manager for Gingerbread?

Sounds just like common android behaviour to me. Eventually your app gets destroyed, when is determined by android. You just need to persist your data in a database or write a temporary file in onDestroy to enable restoring last known state. By the way the android:configChanges setting to handle orientation and so on is really a hack imo, you should do something else instead such as saving variables in onSaveInstanceState and restore it after orientation in onCreate. — cYrixmorten, Nov 06 '13 at 12:08
Thanks. This is really useful. I will work with a temp data at `onDestroy()`. But my challenge is doing this for all tabs the user will have opened.But thanks for the pointer to the right direction. — nmvictor, Nov 06 '13 at 15:00
Not onDestroy(), onPause(). Please read about and learn the Android activity life cycle. — Simon, Nov 06 '13 at 18:45

score 1 · Answer 1 · answered Nov 06 '13 at 12:11

1

Your 1st case is something that you can't really avoid. A real device can not keep your activities around for forever (memory pressure etc). If your app is in the background then it's considered not important for the user (as he's not interacting with it) and it's a good target for the OS to kill if needed.

answered Nov 06 '13 at 12:11

Tauno

66
3

Thanks.I appreciate the info. – nmvictor Nov 06 '13 at 15:02

score 0 · Answer 2 · edited May 23 '17 at 10:32

0

A perhaps useful option is SharedPreference.

This data will live until app is uninstalled but require a String key for each data entry, that it, is it not useful if the fragments are highly dynamic, though it often is possible to work around using arrays and the like.

Look at my answer to How to maintain fragment's state in the application for an example.

edited May 23 '17 at 10:32

Community

1
1

answered Nov 06 '13 at 15:30

cYrixmorten

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Why is my activity restarted despite all my efforts

2 Answers2