Question

How do I retain the state of an activity in android? I have two layouts for portrait and landscape in layout and layout-land. I am loading the value from service at the time I am showing progress dialog. If loaded user rotates the device to landscape at the time also loading. How do I avoid that? user typed content in webview that also refreshed. How do I avoid that, can anybody provide an example?

Thanks

Answer 1

You can use the onRetainNonConfigurationChange() callback to store arbitrary data. It is called just before your application is about to be recreated.

Then, in onCreate() just check if some data were put aside by calling getLastNonConfigurationInstance() that returns the Object you put aside or null.

See this article on android developers.

Here’s a sample borrowed from the link above:

@Override
public Object onRetainNonConfigurationInstance() {
    //this is called by the framework when needed
    //Just return what you want to save here.

    return MyBigObjectThatContainsEverythingIWantToSave;
}

Automagic restore of previously saved state:

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

    final MyDataObject MyBigObjectThatContainsEverythingIWantToSave = (MyDataObject) getLastNonConfigurationInstance();
    if (MyBigObjectThatContainsEverythingIWantToSave == null) {
        //No saved state
        MyBigObjectThatContainsEverythingIWantToSave = loadMyData();
    } else {
        //State was restored, no need to download again.
    }
    ...
}