title: Preventing my Activity to change orientation depending on its content
body: <p>In my app <code>MainActivity</code> contains a <code>BottomNavigation</code>, so it can display different tabs. Now my intention was, to force some of them to stay in portrait orientation, regardless of how the user holds the device. </p>
  
  <p><strong>MainActivity.java</strong>:</p>
  
  <pre><code>public class MainActivity extends AppCompatActivity {
  
  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
  
      BottomNavigationView bottomNav = findViewById(R.id.bottom_navigation);
      bottomNav.setOnNavigationItemSelectedListener(navListener);
      getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, new OverviewFragment()).commit();
  }
  
  private BottomNavigationView.OnNavigationItemSelectedListener navListener =
          new BottomNavigationView.OnNavigationItemSelectedListener() {
              @Override
              public boolean onNavigationItemSelected(@NonNull MenuItem item) {
                  Fragment selectedFragment = null;
  
                  switch (item.getItemId()) {
                      case R.id.nav_overview:
                          selectedFragment = new OverviewFragment();
                          break;
                      case R.id.nav_reports:
                          selectedFragment = new ReportsFragment();
                          break;
                      case R.id.nav_settings:
                          selectedFragment = new SettingsFragment();
                          break;
                  }
                  getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, selectedFragment).commit();
                  return true;
              }
          };
  
  }
  </code></pre>
  
  <p><strong>activity_main.xml</strong></p>
  
  <pre><code>&lt;RelativeLayout 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"
  tools:context=".MainActivity"&gt;
  
  &lt;FrameLayout
      android:id="@+id/fragment_container"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:layout_above="@id/bottom_navigation"/&gt;
  
  &lt;android.support.design.widget.BottomNavigationView
      android:id="@+id/bottom_navigation"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:layout_alignParentBottom="true"
      android:background="?android:attr/windowBackground"
      app:menu="@menu/bottom_navigation"/&gt;
  </code></pre>
  
  <p></p>
  
  <p>At least one tab should be displayable in portrait AND in landscape mode. Do I have to add some stuff into the xml, or do some java magic? Thanks in advance!</p>