popBackStack causes calling oncreateView of fragment again and again

Question

I have 3 fragment A, B,C.I wrote piece of code for replacing them and maintaining backstack:

 public void addFragment(Fragment fragmentToAdd, String fragmentTag)         


        

Answer 1

Remember the life cycle of a fragment. By the time we get back to this, it will start from oncreateView() always. But we can still save data that we will then process in the oncreated to fill our view. for you you can do that:

Main-activity.java

public class MainActivity extends AppCompatActivity implements Fragment2.myListener {
private static final String TAG = "MainActivity";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    Log.e(TAG, "onCreate: ");
    setContentView(R.layout.activity_main);

    Button button = (Button) findViewById(R.id.button);
    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Fragment1 fragment1 = Fragment1.newInstance();
            FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
            fragmentTransaction.replace(R.id.fragmentContainer, fragment1, Fragment1.TAG);
            fragmentTransaction.addToBackStack(Fragment1.TAG);
            fragmentTransaction.commit();
        }
    });

}

@Override
public void onSaveInstanceState(Bundle outState, PersistableBundle outPersistentState) {
    super.onSaveInstanceState(outState, outPersistentState);
    Log.e(TAG, "onSaveInstanceState");
}

@Override
protected void onDestroy() {
    super.onDestroy();
    Log.e(TAG, "onDestroy");
}

@Override
public void bindCount(int newCount) {
    ((Fragment1)getSupportFragmentManager().findFragmentByTag(Fragment1.TAG)).setCount(newCount);
}

}

Fragment1.java

public class Fragment1 extends Fragment {
public static final String TAG = "fragment1";
private static final String SAVE_COUNT = "save_count";

private int count;

public Fragment1() {
}

public static Fragment1 newInstance() {
    Fragment1 fragment = new Fragment1();
    return fragment;
}

@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    Log.e(TAG, "onCreate: ");
    if (savedInstanceState != null) {
        count = savedInstanceState.getInt(SAVE_COUNT);
    }
}

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

    View view =  inflater.inflate(R.layout.fragment_fragment1, container, false);


    Button goToButton = (Button) view.findViewById(R.id.button);
    goToButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Fragment2 fragment2 = Fragment2.newInstance();
            FragmentTransaction fragmentTransaction = getActivity().getSupportFragmentManager().beginTransaction();
            fragmentTransaction.replace(R.id.fragmentContainer, fragment2, Fragment2.TAG);
            fragmentTransaction.addToBackStack(Fragment2.TAG);
            fragmentTransaction.commit();
        }
    });

    return view;
}

public  void setCount(int newCount){
    count = newCount;
}

@Override
public void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    Log.e(TAG, "onSaveInstanceState: ");
    outState.putInt(SAVE_COUNT, count);
}

}

Fragment2.java

public class Fragment2 extends Fragment {
public static final String TAG = "fragment2";

public Fragment2() {
    // Required empty public constructor
}

public static Fragment2 newInstance() {
    Fragment2 fragment = new Fragment2();

    return fragment;
}

myListener listener;

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

    View view = inflater.inflate(R.layout.fragment_fragment2, container, false);
    //Here I am just modifying a value that wants to send to fragment1
    listener.bindCount(45);//newCount

    return view;
}

public interface myListener{
    void bindCount(int newCount);
}

@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
    //initialice listener
    listener = (myListener) getActivity();
}

}

So ... For the communication between fragments we will need your container activity, through interface. As we can see, Fragment2 has an interface that implements its activity and when it is executed, it calls a method where we change the count value in fragment1, which is stored in onSaveInstanceState, so we can resume any modification that occurs even when oncreateview is executed again. this can be used for many other data such as arraylist, string, float, long, object, etc.

sorry my "english"!!!!!