setUserVisibleHint called before onCreateView in Fragment

Question

I am working on ViewPager and using Fragment there I found

setUserVisibleHint() called before onCreateView() in Fragment

I am using Fragment from support library android.support.v4.app.Fragment

Is this is a problem with Library ?

How can I get rid of it ?

EDIT

I Override setUserVisibleHint() and not calling super to get rid of it.

@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
    //FIXED: setUserVisibleHint() called before onCreateView() in Fragment causes NullPointerException
    //super.setUserVisibleHint(isVisibleToUser);
}

Answer 1

// create boolean for fetching data
private boolean isViewShown = false;

@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
    super.setUserVisibleHint(isVisibleToUser);
    if (getView() != null) {
        isViewShown = true;
        // fetchdata() contains logic to show data when page is selected mostly asynctask to fill the data
        fetchData();
    } else {
        isViewShown = false;
    }
} 

Use isViewShown instance variable to decide whether to fetch data in onCreateView() or in setUserVisibleHint().

Below code contains logic for onCreateView():

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.main_layout, container, false);

   // view initialization steps.......

   if (!isViewShown) {
        fetchData();
   } 
   // do other stuff
}

This code will solve your problem. As It solved my problem. :)

This trick will fetch data in onCreateView() for direct jumping from one page to another, whereas when you swipe the view it will fetch the data from setUserVisibleHint() method. :)

Answer 2

you can use this logic, also you can turn off viewDidAppear any time by setting isVisible = false

public class MyFragment extends Fragment {
    private Boolean isStarted = false;
    private Boolean isVisible = false;

    @Override
    public void onStart() {
        super.onStart();
        isStarted = true;
        if (isVisible && isStarted){
            viewDidAppear();
        }
    }

    @Override
    public void setUserVisibleHint(boolean isVisibleToUser) {
        super.setUserVisibleHint(isVisibleToUser);
        isVisible = isVisibleToUser;
        if (isStarted && isVisible) {
            viewDidAppear();
        }
    }

    public void viewDidAppear() {
       // your logic
    }
}

Answer 3

I found the best solution

private boolean isVisible;
private boolean isStarted;

@Override
public void onStart() {
    super.onStart();
    isStarted = true;
    if (isVisible)
        sendRequest(); //your request method
}

@Override
public void onStop() {
    super.onStop();
    isStarted = false;
}

@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
    super.setUserVisibleHint(isVisibleToUser);
    isVisible = isVisibleToUser;
    if (isVisible && isStarted)
        sendRequest(); //your request method
}

It's improved version of fareed namrouti's answer. I tested this on many conditions. It's safe.