title: How to display 3 fragments inside PageViewer
body: <p>Inside a fragment, Im trying to create a ViewPager with 3 fragments that you can swipe between.
  Im having trouble understanding the structure and the errors Im getting..</p>
  
  <pre><code>public class ContactFragment extends Fragment {
  
  FragmentPagerAdapter adapterViewPager;
  private FragmentActivity myContext;
  
  @Override
  public View onCreateView(LayoutInflater inflater, ViewGroup container,
                           Bundle savedInstanceState) {
      ViewGroup rootView = (ViewGroup) inflater.inflate(R.layout.view_pager, container, false);
  
      ViewPager vpPager = (ViewPager) rootView.findViewById(R.id.vpPager);
      adapterViewPager = new MyPagerAdapter(myContext.getSupportFragmentManager());
      vpPager.setAdapter(adapterViewPager);
  
      return rootView;
  }
  
  @Override
  public void onAttach(Activity activity) {
      myContext=(FragmentActivity) activity;
      super.onAttach(activity);
  }
  
   public static class MyPagerAdapter extends FragmentPagerAdapter {
      private static int NUM_ITEMS = 3;
  
      public MyPagerAdapter(FragmentManager fragmentManager) {
          super(fragmentManager);
      }
  
      // Returns total number of pages
      @Override
      public int getCount() {
          return NUM_ITEMS;
      }
  
      // Returns the fragment to display for that page
      @Override
      public Fragment getItem(int position) {
          switch (position) {
              case 0: // Fragment # 0 - This will show FirstFragment
                  return FirstFragment.newInstance(0, "Page # 1");
              case 1: // Fragment # 0 - This will show FirstFragment different title
                  return FirstFragment.newInstance(1, "Page # 2");
              default:
                  return null;
          }
      }
  
      // Returns the page title for the top indicator
      @Override
      public CharSequence getPageTitle(int position) {
          return "Page " + position;
      }
  
    }
  }
  </code></pre>
  
  <p>My ViewPager layout xml looks like this:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:orientation="vertical"&gt;
  
      &lt;android.support.v4.view.ViewPager
      android:id="@+id/vpPager"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"&gt;
  
      &lt;android.support.v4.view.PagerTabStrip
          android:id="@+id/pager_header"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:layout_gravity="top"
          android:paddingBottom="4dp"
          android:paddingTop="4dp" /&gt;
  
      &lt;/android.support.v4.view.ViewPager&gt;
  &lt;/LinearLayout&gt;
  </code></pre>
  
  <p>This is my text Fragment class I instantiate 3 fragments from:</p>
  
  <pre><code>public class FirstFragment extends Fragment {
  // Store instance variables
  private String title;
  private int page;
  
  // newInstance constructor for creating fragment with arguments
  public static FirstFragment newInstance(int page, String title) {
      FirstFragment fragmentFirst = new FirstFragment();
      Bundle args = new Bundle();
      args.putInt("someInt", page);
      args.putString("someTitle", title);
      fragmentFirst.setArguments(args);
      return fragmentFirst;
  }
  
  // Store instance variables based on arguments passed
  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      page = getArguments().getInt("someInt", 0);
      title = getArguments().getString("someTitle");
  }
  
  // Inflate the view for the fragment based on layout XML
  @Override
  public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
      View view = inflater.inflate(R.layout.fragment_layout, container, false);
      TextView tvLabel = (TextView) view.findViewById(R.id.tvLabel);
      tvLabel.setText(page + " -- " + title);
      return view;
  }
  }
  </code></pre>
  
  <p>When i run the app and load the fragment it looks right, but when i try to slide to a new fragment in the pageviewer it crashes:</p>
  
  <pre><code>E/AndroidRuntime﹕ FATAL EXCEPTION: main
  Process: org.example.magnusluca.drawertestapp, PID: 3624
  java.lang.NullPointerException: Attempt to write to field 'android.support.v4.app.FragmentManagerImpl android.support.v4.app.Fragment.mFragmentManager' on a null object reference
  </code></pre>