應用程序墜毀在FragmentTransaction

Question

大家。我的應用程序崩潰，我不知道爲什麼。我最近在學習FragmentTransaction。基本上，activity_main.xml包含我的ActionBar，它帶有兩個包含兩個片段的選項卡，BasicFragment和BFragment。我想要BasicFragment動態顯示一個片段。有人可以請啓迪我這裏出了什麼問題嗎？謝謝。

activity_main.xml中：

<LinearLayout 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:orientation="vertical" 
tools:context=".MainActivity" > 

<LinearLayout 
    android:id="@+id/fragment_container" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" > 
</LinearLayout> 

</LinearLayout> 

MainActivity.java：

public class MainActivity extends Activity { 

public static Context appContext; 

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    actionBar(); 
    FragmentManager fragmentManager = getFragmentManager(); 
    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction(); 
    BasicFragment fragmentee = new BasicFragment(); 
    fragmentTransaction.add(R.id.afrag_container, fragmentee); 
    fragmentTransaction.commit(); 
} 

private void actionBar() { 
    // TODO Auto-generated method stub 
    appContext = getApplicationContext(); 

    // ActionBar 
    ActionBar actionbar = getActionBar(); 
    actionbar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS); 

    actionbar.setDisplayShowTitleEnabled(false); 

    ActionBar.Tab PlayerTab = actionbar.newTab().setText("Fragment A"); 
    ActionBar.Tab StationsTab = actionbar.newTab().setText("Fragment B"); 

    Fragment PlayerFragment = new BasicFragment(); 
    Fragment StationsFragment = new BFragment(); 

    PlayerTab.setTabListener(new TabListener(PlayerFragment)); 
    StationsTab.setTabListener(new TabListener(StationsFragment)); 

    actionbar.addTab(PlayerTab); 
    actionbar.addTab(StationsTab); 
} 

@Override 
public boolean onCreateOptionsMenu(Menu menu) { 
    MenuInflater inflater = getMenuInflater(); 
    inflater.inflate(R.menu.menu_pow, menu); 
    return true; 
} 

@Override 
public boolean onOptionsItemSelected(MenuItem item) { 
    switch (item.getItemId()) { 
    case R.id.menuitem_search: 
     Toast.makeText(appContext, "search", Toast.LENGTH_SHORT).show(); 
     return true; 
    case R.id.menuitem_add: 
     Toast.makeText(appContext, "add", Toast.LENGTH_SHORT).show(); 
     return true; 
    } 
    return false; 
} 

@Override 
protected void onSaveInstanceState(Bundle outState) { 
    super.onSaveInstanceState(outState); 
    outState.putInt("tab", getActionBar().getSelectedNavigationIndex()); 
} 

}

類TabListener實現ActionBar.TabListener { 公共片段片段;

public TabListener(Fragment fragment) { 
    this.fragment = fragment; 
} 

@Override 
public void onTabReselected(Tab tab, FragmentTransaction ft) { 
    Toast.makeText(MainActivity.appContext, "Reselected!", 
      Toast.LENGTH_LONG).show(); 
} 

@Override 
public void onTabSelected(Tab tab, FragmentTransaction ft) { 
    ft.replace(R.id.fragment_container, fragment); 
} 

@Override 
public void onTabUnselected(Tab tab, FragmentTransaction ft) { 
    ft.remove(fragment); 
} 

}

BasicFragment.java：

public class BasicFragment extends Fragment { 

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

}

afragment.xml：

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
android:layout_width="fill_parent" 
android:layout_height="fill_parent" 
android:orientation="vertical" > 

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

</LinearLayout> 

examplefragment.xml：

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
android:layout_width="fill_parent" 
android:layout_height="fill_parent" 
android:orientation="horizontal" > 

<Button android:id="@+id/butt1" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:text="HI!" /> 

</LinearLayout> 

Answer 1

在您的主要活動中，您嘗試訪問afragment.xml中的線性佈局，錯誤也是如此。主要活動顯示佈局activity_main.xml，將afrag_container更改爲位於activity_main.xml中的fragment_container（線性佈局）。