关闭片段上的更新活动

Question

我有一个活动A。一旦A被加载，单击A中的一个按钮就会在A的主页布局上添加一个片段F。现在，一旦在F中，如果我调用getActivity().getSupportFragmentManager().popBackStack();，infacts再次导航到活动A中，那么一旦片段被弹出后堆栈，我是否可以真正地在活动A中进行一些更改？一旦片段被popbackstacked并且你有了你的活动，我就不知道在活动中调用了哪个方法。请帮帮忙。

Answer 1

您可以添加OnBackStackChangedListener()。只需这样做：

getSupportFragmentManager().addOnBackStackChangedListener(new OnBackStackChangedListener()
{
    public void onBackStackChanged() 
    {                   

    }
});

此回调将在后台堆栈上的每次更改后调用。

Answer 2

在您的活动中创建并实现接口

public class MyFragment extends Fragment {
OnFragmentCloseListener mCallback;

// Container Activity must implement this interface
public interface OnFragmentCloseListener {
    public void onClosed(Bundle data);
}

//call this while closing the fragment
Bundle data = new Bundle();
data.putExtra("key"," value");
mCallback.onClosed(data);

@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);

    // This makes sure that the container activity has implemented
    // the callback interface. If not, it throws an exception
    try {
        mCallback = (OnFragmentCloseListener) activity;
    } catch (ClassCastException e) {
        throw new ClassCastException(activity.toString()
                + " must implement OnFragmentCloseListener ");
    }
}

}

在你的活动中

  public static class MainActivity extends Activity
    implements MyFragment.OnFragmentCloseListener {

   public void onClosed(Bundle data) {
    //get the budle data here
   }
}