如何禁用android片段类中按下的后退按钮

Question

我想禁用片段类中的后退按钮.onBackPressed()似乎没有在这个片段中工作.我怎么能禁用后退按钮？

这是我的示例代码:

public class Login extends Fragment {
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
       ,Bundle savedInstanceState) {
        ViewGroup root = (ViewGroup) inflater.inflate(R.layout.login, null);
        return root;
    }

    public void onBackPressed() {
    }
}

Answer 1

您必须覆盖父FragmentActivity类的onBackPressed.因此,将您的代码放在父FragmentActivity中.或者您可以使用以下方法调用父方法:

public void callParentMethod(){
    getActivity().onBackPressed();
}

在FragmentActivity中覆盖onBackPressed方法而不调用其超类来禁用后退按钮.

@Override
public void onBackPressed() {
  //super.onBackPressed();
  //create a dialog to ask yes no question whether or not the user wants to exit
  ...
}

Answer 2

在您的父活动中

@Override
public void onBackPressed() {

    Fragment f = getSupportFragmentManager().findFragmentById(R.id.content_frame);
    if (f instanceof yourfragment) {//the fragment on which you want to handle your back press
        Log.i("BACK PRESSED", "BACK PRESSED");
    }else{
        super.onBackPressed();
    }
}

Answer 3

在你的oncreateView()方法中,你需要编写这段代码,并在KEYCODE_BACk中返回true,那么它将停止特定片段的后退按钮选项

     View v = inflater.inflate(R.layout.xyz, container, false);
    //Back pressed Logic for fragment  
    v.setFocusableInTouchMode(true);  
    v.requestFocus();  
    v.setOnKeyListener(new View.OnKeyListener() {  
    @Override  
    public boolean onKey(View v, int keyCode, KeyEvent event) {
        if (event.getAction() == KeyEvent.ACTION_DOWN) {
            if (keyCode == KeyEvent.KEYCODE_BACK) {

                return true;  
            }  
        }  
        return false;  
    }  
});

Answer 4

OnBackPressedCallback

这是您可以在 Fragment 类中编写以自定义后退按钮按下的代码。

public class MyFragment extends Fragment{

    @Override
    public void onCreate(Bundle savedInstanceState){

        super.onCreate(savedInstanceState);

        OnBackPressedCallback callback = new OnBackPressedCallback(true /* enabled by default */) {
            @Override
            public void handleOnBackPressed() {
                // Handle the back button even
                Log.d("BACKBUTTON", "Back button clicks");
            }
        };

        requireActivity().getOnBackPressedDispatcher().addCallback(this, callback);

     }

}

相关链接

你可以在这里阅读和研究更多

Answer 5

我知道为时已晚，在片段 onCreate

val callback = requireActivity().onBackPressedDispatcher.addCallback(this) {
Log.d("tag","back button pressed")    // Handle the back button event
}

callback.isEnabled

Answer 6

这是您可以onBackPressed()使用新的活动回调管理片段的新方法：

    // Disable onBack click
    requireActivity().onBackPressedDispatcher.addCallback(this) {
      // With blank your fragment BackPressed will be disabled.
    }