Schaltfläche beim Hinzufügen eines neuen Fragments

Question

Ich füge ein Fragment über das andere (Fragment A -> Fragment B), aber wenn ich das tue, wird der Knopf vom ersten Fragment durchgestrichen. Ich verstehe nicht, warum das Hinzufügen eines Fragments über dem anderen Inhalt von Anfang an zeigt.

Hier ist die erste Aktivität. Es hält das erste Fragment (Fragment A):

public class MainActivity extends AppCompatActivity { 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); 
     setSupportActionBar(toolbar); 

     FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab); 
     fab.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View view) { 
       Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG) 
         .setAction("Action", null).show(); 
      } 
     }); 
    } 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     // Inflate the menu; this adds items to the action bar if it is present. 
     getMenuInflater().inflate(R.menu.menu_main, menu); 
     return true; 
    } 

    @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 
     // Handle action bar item clicks here. The action bar will 
     // automatically handle clicks on the Home/Up button, so long 
     // as you specify a parent activity in AndroidManifest.xml. 
     int id = item.getItemId(); 

     //noinspection SimplifiableIfStatement 
     if (id == R.id.action_settings) { 
      return true; 
     } 

     return super.onOptionsItemSelected(item); 
    } 
} 

Hier ist der Code für Fragment A, die das zweite Fragment (Fragment B) aufruft:

public class MainActivityFragment extends Fragment { 

     public MainActivityFragment() { 
     } 

     @Override 
     public View onCreateView(LayoutInflater inflater, ViewGroup container, 
           Bundle savedInstanceState) { 
      return inflater.inflate(R.layout.fragment_main, container, false); 
     } 

     @Override 
     public void onViewCreated(View view, @Nullable Bundle savedInstanceState) { 
      super.onViewCreated(view, savedInstanceState); 

      Button startButton = (Button) view.findViewById(R.id.start_button); 
      startButton.setOnClickListener(new View.OnClickListener() { 
       @Override 
       public void onClick(View v) { 
        GameSetupFragment newGame = new GameSetupFragment(); 
        getFragmentManager().beginTransaction() 
          .addToBackStack("MainActivity") 
          .replace(R.id.fragment, newGame) 
          .commit(); 
       } 
      }); 
     } 

    } 

Hier ist die Klasse, für das Fragment B:

public class GameSetupFragment extends Fragment { 

    @Nullable 
    @Override 
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) { 

     return inflater.inflate(R.layout.game_board_fragment, container, false); 
    } 
} 

Hier sind die xML-Dateien für jeden:

Activity_Main.xml (Main Activity):

<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" 
     tools:context="com.blaine.tictactoe.MainActivity"> 

     <android.support.design.widget.AppBarLayout 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" 
      android:theme="@style/AppTheme.AppBarOverlay"> 

      <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" /> 

     </android.support.design.widget.AppBarLayout> 

     <include layout="@layout/content_main" /> 

     <android.support.design.widget.FloatingActionButton 
      android:id="@+id/fab" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:layout_gravity="bottom|end" 
      android:layout_margin="@dimen/fab_margin" 
      app:srcCompat="@android:drawable/ic_dialog_email" /> 

    </android.support.design.widget.CoordinatorLayout> 

Hier XML für Fragment B (fragment_main.xml)

 <TextView 
      android:layout_width="0dp" 
      android:layout_height="wrap_content" 
      android:text="@string/welcome" 
      android:textAppearance="@android:style/TextAppearance.Large" 
      android:id="@+id/textView" 
      tools:layout_constraintTop_creator="1" 
      tools:layout_constraintRight_creator="1" 
      android:layout_marginStart="69dp" 
      android:layout_marginEnd="69dp" 
      app:layout_constraintRight_toRightOf="parent" 
      android:layout_marginTop="74dp" 
      tools:layout_constraintLeft_creator="1" 
      app:layout_constraintLeft_toLeftOf="parent" 
      app:layout_constraintTop_toTopOf="parent" /> 

     <Button 
      android:id="@+id/start_button" 
      android:layout_width="0dp" 
      android:layout_height="wrap_content" 
      android:text="@string/start" 
      tools:layout_constraintRight_creator="1" 
      tools:layout_constraintBottom_creator="1" 
      android:layout_marginStart="8dp" 
      app:layout_constraintBottom_toBottomOf="parent" 
      android:layout_marginEnd="8dp" 
      app:layout_constraintRight_toRightOf="parent" 
      tools:layout_constraintLeft_creator="1" 
      android:layout_marginBottom="117dp" 
      app:layout_constraintLeft_toLeftOf="parent" /> 

     <android.support.constraint.Guideline 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:id="@+id/guideline" 
      android:orientation="vertical" 
      app:layout_constraintGuide_begin="367dp" 
      tools:layout_editor_absoluteY="0dp" 
      tools:layout_editor_absoluteX="367dp" /> 

     <android.support.constraint.Guideline 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:id="@+id/guideline2" 
      app:layout_constraintGuide_begin="20dp" 
      android:orientation="vertical" 
      tools:layout_editor_absoluteY="0dp" 
      tools:layout_editor_absoluteX="20dp" /> 

     <android.support.constraint.Guideline 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:id="@+id/guideline3" 
      app:layout_constraintGuide_begin="74dp" 
      android:orientation="horizontal" 
      tools:layout_editor_absoluteY="74dp" 
      tools:layout_editor_absoluteX="0dp" /> 



</android.support.constraint.ConstraintLayout> 

Content_main.xml:

<fragment 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/fragment" 
    android:name="com.blaine.tictactoe.fragments.MainActivityFragment" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    app:layout_behavior="@string/appbar_scrolling_view_behavior" 
    tools:layout="@layout/fragment_main" /> 

Fragment B-Code (game_board_fragment.xml):

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    xmlns:android="http://schemas.android.com/apk/res/android" 
    android:background="@color/colorAccent"> 

    <TextView 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="This is just a test"/> 
</RelativeLayout> 

Hierist, was die App aussieht, wenn es läuft:

Answer 1

In Ihrem Content_main.xml FrameLayout nehmen und versuchen Sie Ihr Fragment zu öffnen darin. z.B.

<FrameLayout 
     android:id="@+id/main_fragment" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" /> 

und in Ihrem onCreate von MainActivity, verwenden Sie folgenden Code, um Ihr erstes Fragment wie diese zu öffnen:

String fragmentName = targetFragment.getClass().getName(); 
FragmentManager manager = getSupportFragmentManager(); 
Fragment targetFragment = new MainActivityFragment(); 
manager.popBackStack(); 
manager.beginTransaction() 
       .replace(R.id.main_fragment, targetFragment, fragmentName) 
       .addToBackStack(fragmentName) 
       .commit();