How to keep user inputs on screen orientation change with Android DataBinding library?

Question

I\'m at the very beginning of a new Android project. After playing around with MVP in my last project, I want to implement MVVM with Data Binding this time.

I have a

Answer 1

You need to save state of your view model by overriding of method onSaveInstanceState()in your activity class and restore it in onCreate() method.

private static final String QUESTION = "testViewModel.question";
private TestViewModel mTestViewModel;

@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    ActivityTestBinding binding = DataBindingUtil.setContentView(this, R.layout.activity_test);

    mTestViewModel = new TestViewModel();
    // Check whether we're recreating a previously destroyed instance
    if (savedInstanceState != null) {
         // restore view model state
         String questionVal = savedInstanceState.getString(QUESTION, "");
         mTestViewModel.setQuestion(questionVal);
    }
    binding.setVm(mTestViewModel);
}

@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
    // Save current view model state
    savedInstanceState.putString(QUESTION, mTestViewModel.getQuestion());

    // Always call the superclass so it can save the view hierarchy state
    super.onSaveInstanceState(savedInstanceState);
}

More information about "save-restore" technology you can read at this part of documentation