Fragment ViewState restored in onStart?

Question

When orientation changes, fragment viewState restored only in onStart. After onAttach, onCreateView, onViewCreated and onActivityCreated and even after onCreate. Why? This is too late.

I need to populate db query results to ListView based on some TextView value. Currently i try to do this in onViewCreated. But view state isn't restored at this step.

Can i force restore early? Or how to overcome this problem? Any ideas, please.

PS: i use actionbarsherlock and dependent android support-v4 r7 library

PS2: if i will load data in onStart then it will do additional queries when fragment is resumed after onStop (i can solve this by adding some boolean isLoaded - but this isn't best solution).

Answer 1

In Android API >= 17 (Android 4.2 Jelly Beans) there is a method: public void onViewStateRestored (Bundle savedInstanceState)

which is called before onStart() and after onActivityCreated() as mentioned in docs.

In Android API < 17 there is no such method. But there are two solutions:

1. Don't rely on view state while initializing Fragment and save all required initialization state as Fragment state (i.e. override Fragment#onSaveInstanceState()). Later you can restore fragment state in onCreate(), onCreateView() or onViewCreated().
2. Perform initialization in onStart() as specified in question.

Answer 2

[EDIT 1 - - - - - - -]

// Check to see if the Fragment back stack has been populated

// If not, create and populate the layout.

// so your fragment wont recreated

  YourFragment yourFragment = (YourFragment )fm.findFragmentById(R.id.fragment_container);

  if (yourFragment == null) {
       FragmentTransaction ft = fm.beginTransaction(); 
       ft.replace(R.id.fragment_container, new YourFragment ());       
       ft.commit();
  }

[EDIT 1 - - - - - - -]

/**
 * Listing 4-4: Fragment skeleton code
 * Listing 4-5: Fragment lifecycle event handlers
 */
package com.paad.fragments;

import android.app.Activity;
import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class MySkeletonFragment extends Fragment {

  // Called when the Fragment is attached to its parent Activity.
  @Override
  public void onAttach(Activity activity) {
    super.onAttach(activity);
    // Get a reference to the parent Activity.
  }

  // Called to do the initial creation of the Fragment.
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    // Initialize the Fragment.
  }

  // Called once the Fragment has been created in order for it to
  // create its user interface.
  @Override
  public View onCreateView(LayoutInflater inflater, 
                           ViewGroup container,
                           Bundle savedInstanceState) {
    // Create, or inflate the Fragment's UI, and return it. 
    // If this Fragment has no UI then return null.
    return inflater.inflate(R.layout.my_fragment, container, false);
  }



  // Called once the parent Activity and the Fragment's UI have 
  // been created.
  @Override
  public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
    // Complete the Fragment initialization Ğ particularly anything
    // that requires the parent Activity to be initialized or the 
    // Fragment's view to be fully inflated.
  }

  // Called at the start of the visible lifetime.
  @Override
  public void onStart(){
    super.onStart();
    // Apply any required UI change now that the Fragment is visible.
  }

  // Called at the start of the active lifetime.
  @Override
  public void onResume(){
    super.onResume();
    // Resume any paused UI updates, threads, or processes required
    // by the Fragment but suspended when it became inactive.
  }

  // Called at the end of the active lifetime.
  @Override
  public void onPause(){
    // Suspend UI updates, threads, or CPU intensive processes
    // that don't need to be updated when the Activity isn't
    // the active foreground activity.
    // Persist all edits or state changes
    // as after this call the process is likely to be killed.
    super.onPause();
  }

  // Called to save UI state changes at the
  // end of the active lifecycle.
  @Override
  public void onSaveInstanceState(Bundle savedInstanceState) {
    // Save UI state changes to the savedInstanceState.
    // This bundle will be passed to onCreate, onCreateView, and
    // onCreateView if the parent Activity is killed and restarted.
    super.onSaveInstanceState(savedInstanceState);
  }

  // Called at the end of the visible lifetime.
  @Override
  public void onStop(){
    // Suspend remaining UI updates, threads, or processing
    // that aren't required when the Fragment isn't visible.
    super.onStop();
  }

  // Called when the Fragment's View has been detached.
  @Override
  public void onDestroyView() {
    // Clean up resources related to the View.
    super.onDestroyView();
  }

  // Called at the end of the full lifetime.
  @Override
  public void onDestroy(){
    // Clean up any resources including ending threads,
    // closing database connections etc.
    super.onDestroy();
  }

  // Called when the Fragment has been detached from its parent Activity.
  @Override
  public void onDetach() {
    super.onDetach();
  }
}

source : Professional Android Development 4 - Reto Meier