title: Android TabLayout inside Fragment
body: <p>I am using <code>Navigation Drawer</code> to navigate between fragments they all use the MainActivity toolbar but each fragment has it's own <code>TabLayout</code> with 3 tabs and in each tab I am using <code>RecyclerView</code> to show different text and images.</p>
  
  <p>I did this last time using actvities instead of fragments but now using the drawer it's beter to use fragments. </p>
  
  <p>I have got to a point where the tabs work but as soon as I put the <code>ViewPager</code> in and connect the adapters to the tabs and I open the new fragment from the drawer I get a Null Pointer what could be the problem here? </p>
  
  <p>MainActivity.java</p>
  
  <pre><code>public class MainActivity extends AppCompatActivity
  
      implements NavigationView.OnNavigationItemSelectedListener {
  
  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
      setSupportActionBar(toolbar);
  
      DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
      ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
              this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
      drawer.setDrawerListener(toggle);
      toggle.syncState();
  
      NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
      navigationView.setNavigationItemSelectedListener(this);
  }
  
  @Override
  public void onBackPressed() {
      DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
      if (drawer.isDrawerOpen(GravityCompat.START)) {
          drawer.closeDrawer(GravityCompat.START);
      } else {
          super.onBackPressed();
      }
  }
  
  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
      getMenuInflater().inflate(R.menu.main, menu);
      return true;
  }
  
  @Override
  public boolean onOptionsItemSelected(MenuItem item) {
      int id = item.getItemId();
      return id == R.id.action_settings || super.onOptionsItemSelected(item);
  
  }
  
  @Override
  public boolean onNavigationItemSelected(MenuItem item) {
      int id = item.getItemId();
      Fragment fragment;
  
      if (id == R.id.fragment_one) {
          fragment = new NewFragment();
          FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
          ft.replace(R.id.container, fragment);
          ft.commit();
  
      } else if (id == R.id.fragment_two) {
  
          fragment = new NewFragment();
          FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
          ft.replace(R.id.container, fragment);
          ft.commit();
  
      } else if (id == R.id.fragment_three) {
  
          fragment = new NewFragment();
          FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
          ft.replace(R.id.container, fragment);
          ft.commit();
  
      }
  
      DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
      drawer.closeDrawer(GravityCompat.START);
      return true;
  }
  }
  </code></pre>
  
  <p>activity_main.xml</p>
  
  <pre><code>&lt;android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:app="http://schemas.android.com/apk/res-auto"
  xmlns:tools="http://schemas.android.com/tools"
  android:id="@+id/drawer_layout"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:fitsSystemWindows="true"
  tools:openDrawer="start"&gt;
  
  &lt;android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:app="http://schemas.android.com/apk/res-auto"
      xmlns:tools="http://schemas.android.com/tools"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:fitsSystemWindows="true"
      tools:context="com.xcandy.guideforfifa17.MainActivity"&gt;
  
      &lt;android.support.design.widget.AppBarLayout
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:theme="@style/AppTheme.AppBarOverlay"&gt;
  
          &lt;android.support.v7.widget.Toolbar
              android:id="@+id/toolbar"
              android:layout_width="match_parent"
              android:layout_height="?attr/actionBarSize"
              android:background="?attr/colorPrimary"
              app:popupTheme="@style/AppTheme.PopupOverlay" /&gt;
  
      &lt;/android.support.design.widget.AppBarLayout&gt;
  
      &lt;include layout="@layout/content_main" /&gt;
  
  &lt;/android.support.design.widget.CoordinatorLayout&gt;
  
  &lt;android.support.design.widget.NavigationView
      android:id="@+id/nav_view"
      android:layout_width="wrap_content"
      android:layout_height="match_parent"
      android:layout_gravity="start"
      android:fitsSystemWindows="true"
      app:headerLayout="@layout/nav_header_main"
      app:menu="@menu/activity_main_drawer" /&gt;
  
  &lt;/android.support.v4.widget.DrawerLayout&gt;
  </code></pre>
  
  <p>NewFragment.java</p>
  
  <pre><code>public class NewFragment extends Fragment {
  
  private RecyclerView mRecyclerView;
  
  
  @Override
  public View onCreateView(LayoutInflater inflater, ViewGroup container,
                           Bundle savedInstanceState) {
      View view = inflater.inflate(R.layout.activity_fragment_one, container, false);
  
      TabLayout tabLayout = (TabLayout) view.findViewById(R.id.tabs);
      tabLayout.addTab(tabLayout.newTab().setText("A"));
      tabLayout.addTab(tabLayout.newTab().setText("B"));
      tabLayout.addTab(tabLayout.newTab().setText("C"));
  
      final ViewPager viewPager = (ViewPager) view.findViewById(R.id.viewpager);
  
      mRecyclerView = (RecyclerView) view.findViewById(R.id.recycler_view);
  
      RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(getActivity());
      mRecyclerView.setLayoutManager(mLayoutManager);
  
  
      viewPager.setAdapter(new PagerAdapter
              (getFragmentManager(), tabLayout.getTabCount()));
      viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
      tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
  
          @Override
          public void onTabSelected(TabLayout.Tab tab) {
              viewPager.setCurrentItem(tab.getPosition());
          }
  
          @Override
          public void onTabUnselected(TabLayout.Tab tab) {
  
          }
  
          @Override
          public void onTabReselected(TabLayout.Tab tab) {
  
          }
      });
  
      return view;
  }
  
  public class PagerAdapter extends FragmentStatePagerAdapter {
      int mNumOfTabs;
  
      public PagerAdapter(FragmentManager fm, int NumOfTabs) {
          super(fm);
          this.mNumOfTabs = NumOfTabs;
      }
  
  
  
      @Override
      public Fragment getItem(int position) {
  
          switch (position) {
              case 0:
  
                  RecyclerView.Adapter mAdapter = new AdapterOne();
                  mRecyclerView.setAdapter(mAdapter);
  
              case 1:
  
                  mAdapter = new AdapterTwo();
                  mRecyclerView.setAdapter(mAdapter);
  
              case 2:
  
                  mAdapter = new AdapterThree();
                  mRecyclerView.setAdapter(mAdapter);
  
              default:
                  return null;
          }
      }
  
      @Override
      public int getCount() {
          return mNumOfTabs;
      }
  }
  }
  </code></pre>
  
  <p>activity_fragment.xml</p>
  
  <pre><code>&lt;android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:app="http://schemas.android.com/apk/res-auto"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:fitsSystemWindows="true"
  tools:context=".NewFragment"&gt;
  
  &lt;android.support.design.widget.AppBarLayout
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:theme="@style/AppTheme.AppBarOverlay"&gt;
  
      &lt;android.support.design.widget.TabLayout
          android:id="@+id/tabs"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          app:tabMode="fixed"
          app:tabGravity="fill"/&gt;
  
  &lt;/android.support.design.widget.AppBarLayout&gt;
  
  &lt;android.support.v4.view.ViewPager
      android:id="@+id/viewpager"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:background="@android:color/white"/&gt;
  
  &lt;android.support.v7.widget.RecyclerView
      android:id="@+id/recycler_view"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      /&gt;
  
  &lt;/android.support.design.widget.CoordinatorLayout&gt;
  </code></pre>
  
  <p>Error Log</p>
  
  <pre><code>                  --------- beginning of crash
  06-23 11:19:56.985 2466-2466/com.candyx.sims E/AndroidRuntime: FATAL EXCEPTION: main
                                                                 Process: com.candyx.sims, PID: 2466
                                                                 java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.RecyclerView.setLayoutManager(android.support.v7.widget.RecyclerView$LayoutManager)' on a null object reference
                                                                     at com.candyx.sims.BlankFragment.onCreateView(BlankFragment.java:38)
                                                                     at android.support.v4.app.Fragment.performCreateView(Fragment.java:1974)
                                                                     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1067)
                                                                     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1252)
                                                                     at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:742)
                                                                     at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1617)
                                                                     at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:517)
                                                                     at android.os.Handler.handleCallback(Handler.java:739)
                                                                     at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                     at android.os.Looper.loop(Looper.java:135)
                                                                     at android.app.ActivityThread.main(ActivityThread.java:5254)
                                                                     at java.lang.reflect.Method.invoke(Native Method)
                                                                     at java.lang.reflect.Method.invoke(Method.java:372)
                                                                     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
                                                                     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
  06-23 11:23:14.912 5839-5873/com.candyx.sims D/OpenGLRenderer: Use EGL_SWAP_BEHAVIOR_PRESERVED: true
  
                                                                 [ 06-23 11:23:14.920  5839: 5839 D/         ]
                                                                 HostConnection::get() New Host Connection established 0xb4125190, tid 5839
  06-23 11:23:14.927 5839-5839/com.candyx.sims D/Atlas: Validating map...
  06-23 11:23:15.011 5839-5873/com.candyx.sims I/OpenGLRenderer: Initialized EGL, version 1.4
  06-23 11:23:15.027 5839-5873/com.candyx.sims D/OpenGLRenderer: Enabling debug mode 0
  06-23 11:23:15.039 5839-5873/com.candyx.sims W/EGL_emulation: eglSurfaceAttrib not implemented
  06-23 11:23:15.039 5839-5873/com.candyx.sims W/OpenGLRenderer: Failed to set EGL_SWAP_BEHAVIOR on surface 0xae838600, error=EGL_SUCCESS
  06-23 11:23:16.444 5839-5839/com.candyx.sims W/PathParser: Points are too far apart 4.000000596046461
  06-23 11:23:17.342 5839-5839/com.candyx.sims W/PathParser: Points are too far apart 4.000000596046461
  06-23 11:23:17.350 5839-5839/com.candyx.sims I/AppCompatViewInflater: app:theme is now deprecated. Please move to using android:theme instead.
  06-23 11:23:17.369 5839-5839/com.candyx.sims D/AndroidRuntime: Shutting down VM
  06-23 11:23:17.369 5839-5839/com.candyx.sims E/AndroidRuntime: FATAL EXCEPTION: main
                                                                 Process: com.candyx.sims, PID: 5839
                                                                 java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.RecyclerView.setLayoutManager(android.support.v7.widget.RecyclerView$LayoutManager)' on a null object reference
                                                                     at com.candyx.sims.NewFragment.onCreateView(NewFragment.java:38)
                                                                     at android.support.v4.app.Fragment.performCreateView(Fragment.java:1974)
                                                                     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1067)
                                                                     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1252)
                                                                     at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:742)
                                                                     at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1617)
                                                                     at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:517)
                                                                     at android.os.Handler.handleCallback(Handler.java:739)
                                                                     at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                     at android.os.Looper.loop(Looper.java:135)
                                                                     at android.app.ActivityThread.main(ActivityThread.java:5254)
                                                                     at java.lang.reflect.Method.invoke(Native Method)
                                                                     at java.lang.reflect.Method.invoke(Method.java:372)
                                                                     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
                                                                     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
  06-23 11:25:16.961 7518-7518/com.candyx.sims W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter android.support.graphics.drawable.VectorDrawableCompat.updateTintFilter(android.graphics.PorterDuffColorFilter, android.content.res.ColorStateList, android.graphics.PorterDuff$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable
  06-23 11:25:17.078 7518-7548/com.candyx.sims D/OpenGLRenderer: Use EGL_SWAP_BEHAVIOR_PRESERVED: true
  
                                                                 [ 06-23 11:25:17.081  7518: 7518 D/         ]
                                                                 HostConnection::get() New Host Connection established 0xb412a1f0, tid 7518
  06-23 11:25:17.082 7518-7518/com.candyx.sims D/Atlas: Validating map...
  06-23 11:25:17.109 7518-7548/com.candyx.sims I/OpenGLRenderer: Initialized EGL, version 1.4
  06-23 11:25:17.126 7518-7548/com.candyx.sims D/OpenGLRenderer: Enabling debug mode 0
  06-23 11:25:17.134 7518-7548/com.candyx.sims W/EGL_emulation: eglSurfaceAttrib not implemented
  06-23 11:25:17.134 7518-7548/com.candyx.sims W/OpenGLRenderer: Failed to set EGL_SWAP_BEHAVIOR on surface 0xb41234c0, error=EGL_SUCCESS
  06-23 11:25:31.030 7518-7518/com.candyx.sims W/PathParser: Points are too far apart 4.000000596046461
  06-23 11:25:32.174 7518-7518/com.candyx.sims W/PathParser: Points are too far apart 4.000000596046461
  06-23 11:25:32.187 7518-7518/com.candyx.sims I/AppCompatViewInflater: app:theme is now deprecated. Please move to using android:theme instead.
  06-23 11:25:32.207 7518-7518/com.candyx.sims D/AndroidRuntime: Shutting down VM
  06-23 11:25:32.207 7518-7518/com.candyx.sims E/AndroidRuntime: FATAL EXCEPTION: main
                                                                 Process: com.candyx.sims, PID: 7518
                                                                 java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.RecyclerView.setLayoutManager(android.support.v7.widget.RecyclerView$LayoutManager)' on a null object reference
                                                                     at com.candyx.sims.NewFragment.onCreateView(NewFragment.java:38)
                                                                     at android.support.v4.app.Fragment.performCreateView(Fragment.java:1974)
                                                                     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1067)
                                                                     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1252)
                                                                     at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:742)
                                                                     at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1617)
                                                                     at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:517)
                                                                     at android.os.Handler.handleCallback(Handler.java:739)
                                                                     at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                     at android.os.Looper.loop(Looper.java:135)
                                                                     at android.app.ActivityThread.main(ActivityThread.java:5254)
                                                                     at java.lang.reflect.Method.invoke(Native Method)
                                                                     at java.lang.reflect.Method.invoke(Method.java:372)
                                                                     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
                                                                     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
  </code></pre>