title: Switching to a specific fragment gives strange java.lang.NullPointerException
body: <p>Here is the problem i am currently facing. I have switched from Eclipse with ADT plugin to Android Studio recently and an error i never encountered on Eclipse appeared with Android studio.</p>
  
  <p>When I switch to a specific fragment called "LineFragment" I get the following error :</p>
  
  <pre><code>java.lang.NullPointerException: Attempt to write to field 'int android.support.v4.app.Fragment.mNextAnim' on a null object reference
          at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:708)
          at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1489)
          at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:486)
          at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141)
          at android.support.v4.view.ViewPager.populate(ViewPager.java:1073)
          at android.support.v4.view.ViewPager.populate(ViewPager.java:919)
          at android.support.v4.view.ViewPager$3.run(ViewPager.java:249)
          at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767)
          at android.view.Choreographer.doCallbacks(Choreographer.java:580)
          at android.view.Choreographer.doFrame(Choreographer.java:549)
          at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753)
          at android.os.Handler.handleCallback(Handler.java:739)
          at android.os.Handler.dispatchMessage(Handler.java:95)
          at android.os.Looper.loop(Looper.java:135)
          at android.app.ActivityThread.main(ActivityThread.java:5221)
          at java.lang.reflect.Method.invoke(Native Method)
          at java.lang.reflect.Method.invoke(Method.java:372)
          at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
  </code></pre>
  
  <p>It seems to have something to do with the fragment being null or so. I have search on the internet but only very few people have encoutered something like that.</p>
  
  <p>Here is the code of my fragment (it extends android.support.v4.app.Fragment like all the 3 fragments)</p>
  
  <pre><code>public class LineFragment extends Fragment{
  
  private View v;
  private ListView list;
  private LineList listAdapter;
  private Home home;  // Current activity
  
  public static LineFragment  newInstance(String chaine) {
      LineFragment  fragment = new LineFragment ();
      Bundle args = new Bundle();
      args.putString("LIGNE", chaine);
      fragment.setArguments(args);
      return fragment;
  }
  
  @Override
  public void onActivityCreated(Bundle savedState) {
      super.onActivityCreated(savedState);
      registerForContextMenu(list);
  }
  
  @Override
  public View onCreateView(LayoutInflater inflater, ViewGroup container,
      Bundle savedInstanceState) {
      v = inflater.inflate(R.layout.fragment_ligne, container, false); 
      home = (Home) this.getActivity();
      initInterface();
      attachReactions();
      setHasOptionsMenu(true);
      return v;
  }
  
  @Override
   public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {     
      inflater.inflate(R.menu.line_menu, menu);
  
    MenuItem searchMenuItem = menu.findItem(R.id.action_search);
  
    SearchManager searchManager = (SearchManager) getActivity().getSystemService( Context.SEARCH_SERVICE );
    SearchView search = (SearchView) MenuItemCompat.getActionView(searchMenuItem);
    SearchViewCompat.setInputType(search, InputType.TYPE_CLASS_TEXT|InputType.TYPE_TEXT_VARIATION_POSTAL_ADDRESS);
  
  
  search.setSearchableInfo(searchManager.getSearchableInfo(home.getComponentName()));
  //search.setSubmitButtonEnabled(true);
  
  
  int id = search.getContext().getResources().getIdentifier("android:id/search_src_text", null, null);
  TextView textView = (TextView) search.findViewById(id);
  textView.setTextColor(Color.WHITE);
  textView.setHintTextColor(Color.WHITE);
  
  search.setOnQueryTextListener(new GreenOnQueryTextListener(list));
  
  super.onCreateOptionsMenu(menu, inflater);
   }
  @Override
  public void onResume() {
      super.onResume();
      Log.d("OnResume()", "Ligne");
  }
  
  @Override
  public void setUserVisibleHint(boolean visible){
      super.setUserVisibleHint(visible);
      if (visible &amp;&amp; isResumed()){
          //Only manually call onResume if fragment is already visible
          //Otherwise allow natural fragment lifecycle to call onResume
          onResume();
      }
  }
  
  /**
   * Initializes the graphical interface of the fragment.
   */
  private void initInterface(){
      list = (ListView) v.findViewById(R.id.list);
      list.setTextFilterEnabled(true);
  }
  
  /**
   * Sets the reactions of the control elements
   */
  private void attachReactions(){
      ArrayList&lt;Ligne&gt; lignes = new ArrayList&lt;Ligne&gt;(Globale.engine.getReseau().getLignes().values());
      listAdapter = new LineList(getActivity(), lignes);
      list.setAdapter(listAdapter);
      list.setOnItemClickListener(new LineClickListener(home));
  }
  </code></pre>
  
  <p>Here is my PagerAdapter : </p>
  
  <pre><code>public class KiceoFragmentPagerAdapter extends FragmentPagerAdapter{
  
  private final int PAGE_COUNT = 3;
  
      public KiceoFragmentPagerAdapter(FragmentManager fm) {
          super(fm);
          // TODO Auto-generated constructor stub
      }
  
  
      @Override
      public int getCount() {
          return PAGE_COUNT;
      }
  
      @Override
      public Fragment getItem(int position) {     
  
          switch (position) {
          case 0:
              // Top Rated fragment activity
              return new LineFragment();
          case 1:
              // Games fragment activity
              return new StopFragment();
          case 2:
              // Movies fragment activity
              return new CustomMapFragment();
          }
  
          return new LineFragment();
      }
  }
  </code></pre>
  
  <p>Does anyone have a clue where this is coming from ? Does it really have something to do with Android Studio ? Thanx</p>
  
  <p>I tried switching to support V13 fragments but It didn't change anything.</p>