ViewPager inside Fragment causes NullPointerException

Question

I am trying to use ViewPager inside a Fragment and get

03-01 15:23:05.375 3937-3937/com.example.android.navigationdrawerexample E/AndroidRuntime﹕ FATAL EXCEPTION: main java.lang.NullPointerException at com.example.android.navigationdrawerexample.SpaFragment.onCreateView(SpaFragment.java:50) at android.app.Fragment.performCreateView(Fragment.java:1695)

Code:

public class SpaFragment extends Fragment { public SpaFragment(){} private SpaList mSpa; private TabHost tabs; private FragmentActivity mFragmentActivity; private View rootView; public void setSpa(SpaList s) { mSpa=s; } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { rootView = inflater.inflate(R.layout.fragment_spa, container, false); ViewPager pager = (ViewPager) rootView.findViewById(R.id.pager); pager.setAdapter(new MyPagerAdapter(mFragmentActivity.getSupportFragmentManager())); return rootView; } @Override public void onAttach(Activity activity) { mFragmentActivity = (FragmentActivity) activity; Log.d("ACTIVITY on attach"+mFragmentActivity,"\n"); super.onAttach(activity); } private class MyPagerAdapter extends FragmentPagerAdapter { public MyPagerAdapter(FragmentManager fm) { super(fm); } @Override public CharSequence getPageTitle(int position) { return "Title " + position; } @Override public android.support.v4.app.Fragment getItem(int pos) { switch(pos) { case 0: return FirstFragment.newInstance("FirstFragment, Instance 1"); case 1: return SecondFragment.newInstance("SecondFragment, Instance 1"); default: return FirstFragment.newInstance("ThirdFragment, Default"); } } @Override public int getCount() { return 2; } } }

remove Log.d("ACTIVITY on create", String.valueOf(mFragmentActivity)); — M D
– M D, Commented Mar 3, 2014 at 16:26

Philipp Jahoda · Accepted Answer · 2014-03-03 16:29:21Z

1

You are running into a NullPointerException because you are invoking a method on an object that is NULL at that time.

This could be because your

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

method is called before your

 @Override public void onAttach(Activity activity) { }

method, and therefore, your variable mFragmentActivity is NULL. In that case, your code

String.valueOf(mFragmentActivity);

will throw a NullPointerException.

answered Mar 3, 2014 at 16:29

Philipp Jahoda

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6 Comments

M D Over a year ago

@PJ that's what i m talk in about.

SERG Over a year ago

i removed Log.d and still get the same error. How can i pass ref to Activity before onCreateView?

Philipp Jahoda Over a year ago

You also need to remove this line: pager.setAdapter(new MyPagerAdapter(mFragmentActivity.getSupportFragmentManager())); Just call getActivity() inside your onCreateView() method.

SERG Over a year ago

but i need to pass FragmentManager to MyPagerAdapter() in pager.setAdapter(new MyPagerAdapter()); i am new to java and simply dot get what is wrong. thanks

Philipp Jahoda Over a year ago

use ((FragmentActivity) getActivity()).getSupportFragmentManager() instead of mFragmentManager

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