Question

如果我单击后退按钮（设备后退按钮），我试图从我的各种片段打开主片段。但不是替换片段，应用程序关闭，设备的菜单屏幕出现。我不知道出了什么问题。而且没有错误。请帮帮我..

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);
 }

 }

我甚至尝试在片段中使用onBackPressed（）方法。但没有理想的输出。

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();
}

}

请帮帮我..告诉我哪里出错了。我只想要打开哪个片段，点击后退按钮它应该打开homefragment类..

Answer 1

要使用片段处理返回导航，您必须使用：

  // 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();

您可以阅读更多内容 Implementing navigation

片段后退按钮代码更改

1 个答案: