片段onKeyDown（）不按預期工作

Question

我有FragOne調用FragTest和FragTest調用FragBook的順序調用的框架。當我按下後退按鈕時，當前的片段是FragBook，FragTest僅顯示爲分秒，然後我的應用程序被髮送到應用程序托盤。

@Override 
public boolean onKeyDown(int keyCode, KeyEvent event) { 
    FragmentManager fragManager = getSupportFragmentManager(); 
    Fragment frag = fragManager.findFragmentByTag("Frag_Book"); 

    if ((keyCode == KeyEvent.KEYCODE_BACK)) { 
     if (frag.isVisible()) { 
      fragManager.beginTransaction() 
        .replace(R.id.container, Fragment.instantiate(MainActivity.this, fragments[1]),"Frag_Test") 
        .commit(); 
     } 
    } 
    return super.onKeyDown(keyCode, event); 
} 

我在哪裏弄錯了方法？謝謝...

Answer 1

@Override 
    public boolean onKeyDown(int keyCode, KeyEvent event) { 
     FragmentManager fragManager = getSupportFragmentManager(); 
     Fragment frag = fragManager.findFragmentByTag("Frag_Book"); 

     if ((keyCode == KeyEvent.KEYCODE_BACK)) { 
      if (frag.isVisible()) { 
       fragManager.beginTransaction() 
         .replace(R.id.container, Fragment.instantiate(MainActivity.this, fragments[1]),"Frag_Test") 
         .commit(); 
      return true; //"------------- should be add" 
      } 
     } 
     return super.onKeyDown(keyCode, event); 
    }