title: Fragments in AppCompatActivity
body: <p>Could I use this extension if I want to use Fragments in my swipe view activity?</p>
  
  <pre><code>public class Overview_Screen extends AppCompatActivity {
  </code></pre>
  
  <p>My Fragment classes use this one:</p>
  
  <pre><code>public class MessagesFragmentPortrait extends android.support.v4.app.Fragment {
  </code></pre>
  
  <p>I am asking this because my app keeps crashing...<br>
  Here is my main Activity:</p>
  
  <pre><code>public class Overview_Screen extends AppCompatActivity {
  
      private SectionsPagerAdapter mSectionsPagerAdapter;
  
      private ViewPager mViewPager;
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_overview_screen);
  
          Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
          setSupportActionBar(toolbar);
  
          mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
          mViewPager = (ViewPager) findViewById(R.id.container);
          mViewPager.setAdapter(mSectionsPagerAdapter);
  
          TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
          tabLayout.setupWithViewPager(mViewPager);
  
      }
  
      @Override
      public boolean onCreateOptionsMenu(Menu menu) {
          getMenuInflater().inflate(R.menu.menu_overview_screen, menu);
          return true;
      }
  
      @Override
      public boolean onOptionsItemSelected(MenuItem item) {
          int id = item.getItemId();
  
          if (id == R.id.action_settings) {
              Intent settings_intent = new Intent(this, Settings_Screen.class);
              startActivity(settings_intent);
              return true;
          }
  
          return super.onOptionsItemSelected(item);
      }
  
      public static class SectionsPagerAdapter extends FragmentPagerAdapter {
  
          public SectionsPagerAdapter(FragmentManager fm) {
              super(fm);
          }
  
          @Override
          public Fragment getItem(int i) {
              switch (i) {
                  case 0:
                      return new AccountFragmentPortrait();
                  case 1:
                      return new FeedFragmentPortrait();
                  default:
                      return new MessagesFragmentPortrait();
              }
          }
  
          @Override
          public int getCount() {
              return 3;
          }
  
          @Override
          public CharSequence getPageTitle(int position) {
              switch (position) {
                  case 0:
                      return "Account";
                  case 1:
                      return "Feed";
                  case 2:
                      return "Messages";
              }
              return null;
          }
      }
  }
  </code></pre>
  
  <p>and here is my stack trace:</p>
  
  <pre><code>FATAL EXCEPTION: main
    Process: de.lukas_schroederoutlook.connect, PID: 3364
    java.lang.RuntimeException: Unable to start activity ComponentInfo{de.lukas_schroederoutlook.connect/de.lukas_schroederoutlook.connect.Overview_Screen}:
    android.view.InflateException: Binary XML file line #41: Binary XML file line #41: Error inflating class fragment
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2665)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726)
        at android.app.ActivityThread.-wrap12(ActivityThread.java)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:154)
        at android.app.ActivityThread.main(ActivityThread.java:6119)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
     Caused by: android.view.InflateException: Binary XML file line #41: Binary XML file line #41: Error inflating class fragment
     Caused by: android.view.InflateException: Binary XML file line #41: Error inflating class fragment
     Caused by: java.lang.NullPointerException
        at java.lang.VMClassLoader.findLoadedClass(Native Method)
        at java.lang.ClassLoader.findLoadedClass(ClassLoader.java:742)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:362)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:312)
        at android.support.v4.app.Fragment.isSupportFragmentClass(Fragment.java:469)
        at android.support.v4.app.FragmentManagerImpl.onCreateView(FragmentManager.java:2384)
        at android.support.v4.app.FragmentController.onCreateView(FragmentController.java:120)
        at android.support.v4.app.FragmentActivity.dispatchFragmentsOnCreateView(FragmentActivity.java:378)
        at android.support.v4.app.BaseFragmentActivityHoneycomb.onCreateView(BaseFragmentActivityHoneycomb.java:33)
        at android.support.v4.app.FragmentActivity.onCreateView(FragmentActivity.java:77)
        at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:777)
        at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:727)
        at android.view.LayoutInflater.rInflate(LayoutInflater.java:858)
        at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:821)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:518)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:426)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:377)
        at android.support.v7.app.AppCompatDelegateImplV9.setContentView(AppCompatDelegateImplV9.java:284)
        at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:143)
        at de.lukas_schroederoutlook.connect.Overview_Screen.onCreate(Overview_Screen.java:42)
        at android.app.Activity.performCreate(Activity.java:6679)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2618)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726)
        at android.app.ActivityThread.-wrap12(ActivityThread.java)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:154)
        at android.app.ActivityThread.main(ActivityThread.java:6119)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
  </code></pre>
  
  <p>And lastly, here is my overview screen xml:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&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:id="@+id/main_content"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:fitsSystemWindows="true"
      tools:context="de.lukas_schroederoutlook.connect.Overview_Screen"&gt;
  
  &lt;android.support.design.widget.AppBarLayout
      android:id="@+id/appbar"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:paddingTop="@dimen/appbar_padding_top"
      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:layout_scrollFlags="scroll|enterAlways"
          app:popupTheme="@style/AppTheme.PopupOverlay"&gt;
  
      &lt;/android.support.v7.widget.Toolbar&gt;
  
      &lt;android.support.design.widget.TabLayout
          android:id="@+id/tabs"
          android:layout_width="match_parent"
          android:layout_height="wrap_content" /&gt;
  
  &lt;/android.support.design.widget.AppBarLayout&gt;
  
  &lt;android.support.v4.view.ViewPager
      android:id="@+id/container"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      app:layout_behavior="@string/appbar_scrolling_view_behavior" /&gt;
  
  &lt;fragment
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:id="@+id/feed_fragment_portrait"/&gt;
  
  &lt;fragment
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:id="@+id/feed_fragment_landscape"/&gt;
  </code></pre>
  
  <p></p>
  
  <p>And my overview screen fragment xml:</p>
  
  <pre><code>&lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:paddingBottom="@dimen/activity_vertical_margin"
  android:paddingLeft="@dimen/activity_horizontal_margin"
  android:paddingRight="@dimen/activity_horizontal_margin"
  android:paddingTop="@dimen/activity_vertical_margin"
  tools:context="de.lukas_schroederoutlook.connect.Overview_Screen$PlaceholderFragment"&gt;
  
  &lt;TextView
      android:id="@+id/section_label"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content" /&gt;
  </code></pre>
  
  <p></p>