Is this possible to restore the state of data in UI of fragment while calling fragment again?

Question

If I have Fragment A and Fragment B. I call Fragment B from A using below code

FragmentManager fragmentManager =getFragmentManager();
    FragmentTransaction fragmentTransaction =
            fragmentManager.beginTransaction();


    fragmentTransaction.add(R.id.frame_step, fragment,TAG).hide(SourceFragment.this).addToBackStack((SourceFragment.class.getName()));
    fragmentTransaction.commit();

Now in Fragment B I have EditText & I have entered "Hello" in it, if I press back button from Fragment B then according to getSupportFragmentManager().popBackStack(); it will resume Fragment A

Now if I again call Fragment B from Fragment A I want that FragmentB will not get created again and still I can see "Hello" inside EditText.

Note -- I do not want to use variables or shared pref for this as i have multiple fragments with multiple views like a big form. Is there anything that can just call fragment from its resume state instead of calling it again or if i can check if this fragment has already created . Thanks in advance

Answer 1

What you want is possible. You need to save fragment state before forward navigation and restore it after fragment is restored from backstack.

In Fragment

private Bundle savedState = null;

 @Override
    public void onDestroyView() {
        super.onDestroyView();
        savedState = saveState();
    }

    private Bundle saveState() { /* called either from onDestroyView() or onSaveInstanceState() */
        Bundle state = new Bundle();
        state.putCharSequence("TEXT_HELLO_WORD", helloWordTextView.getText());
        return state;
    }

 @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        /* (...) */

        if(savedInstanceState != null && savedState == null) {
            savedState = savedInstanceState.getBundle("FRAGMENT_HELLO_WORD");
        }
        if(savedState != null) {
         helloWordTextView.setText(savedState.getCharSequence("TEXT_HELLO_WORD"));
        }
        savedState = null;

        /* (...) */
        return view;
    }
...
@Override
public void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);

    //Save the fragment's state here somehow like this
    outState.putBundle("FRAGMENT_HELLO_WORD", (savedState != null) ? savedState : saveState());
}

in Activity

public void onCreate(Bundle savedInstanceState) {
    ...
    if (savedInstanceState != null) {
        //Restore the fragment's instance
        mContent = getSupportFragmentManager().getFragment(savedInstanceState, "myFragmentName");
        ...
    }
    ...
}

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

    //Save the fragment's instance
    getSupportFragmentManager().putFragment(outState, "myFragmentName", mContent);
}

Answer compiled from here and here

Hope it helps.