片段後退按鈕代碼更改

Question

我試圖從我的各種片段打開家庭片段，如果我單擊後退按鈕（設備後退按鈕）。但不是替換片段，應用程序關閉並出現設備的菜單畫面。我無法解決發生了什麼問題。並沒有錯誤。請幫助我..

HomeFragment：

public class HomeFragment extends Fragment { 

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

    View view = inflater.inflate(R.layout.home, container, false); 

    return view; 

} 

OneFragment：

public class OneFragment extends Fragment { 

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

    View view = inflater.inflate(R.layout.activity_one, container, false); 

    OnKeyListener pressed = new OnKeyListener() { 
     @Override 
     public boolean onKey(View v, int keyCode, KeyEvent event) { 
      if (keyCode == KeyEvent.KEYCODE_BACK) { 
       return true; 
      } 
      return false; 
     } 
    }; 
    view.setOnKeyListener(pressed); 
    return view; 

} 

public boolean onKeyDown(int keyCode, KeyEvent event) { 

    if (keyCode == KeyEvent.KEYCODE_BACK) { 
     Fragment newFragment = new HomeFragment(); 
     FragmentTransaction transaction = getFragmentManager() 
       .beginTransaction(); 
     transaction.replace(R.id.content_frame, newFragment); 
     // transaction.addToBackStack(null); 
     transaction.commit(); 
     return false; 
    } 
    return super.getActivity().onKeyDown(keyCode, event); 
} 

} 

我甚至使用onBackPressed嘗試（）的片段方法。但沒有期望的輸出。

twoFragment：

public class TwoFragment extends Fragment { 

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

    View view = inflater.inflate(R.layout.activity_two, container, false); 

    return view; 

} 
    public void onBackPressed() { 
    Fragment newFragment = new WordFragment(); 
    FragmentTransaction transaction = getFragmentManager() 
      .beginTransaction(); 
    transaction.replace(R.id.content_frame, newFragment); 
    // transaction.addToBackStack(null); 
    transaction.commit(); 

    super.getActivity().onBackPressed(); 
} 

}

請幫助我..告訴我，我要去哪裏錯了。 我只想說哪個片段被打開，同時單擊後退按鈕應該打開homefragment類..

Answer 1

爲了處理回用導航片段，你必須使用：

// Works with either the framework FragmentManager or the 
    // support package FragmentManager (getSupportFragmentManager). 
    getSupportFragmentManager().beginTransaction() 
           .add(detailFragment, "detail") 
           // Add this transaction to the back stack 
           .addToBackStack() 
           .commit(); 

你可以閱讀更多的 Implementing navigation