Android-活动和返回的片段

Question

在Android中，当我们用一个新的片段替换容器视图时，我们可以使用replace（）和addToBackStack()，因此按下back按钮就可以转到上一个片段。

但如果出现以下情况怎么办：

在Activity1中，我可以按下back按钮从fragment2转到fragment1。但当fragment2启动另一个活动时，从Activity2按下back按钮，它会将我带到Activity1中的fragment1。如何使从Activity2按下的back按钮返回到Activity1中的fragment2？

代码：

// In Activity1 - starts with a ListFragment
@Override
protected void onResume() {
    super.onResume();

    getFragmentManager().beginTransaction()
            .replace(R.id.container, ListFragment.newInstance(0))
            .commit();
}

// In Activity1 , each item in list replaces the container view 
// with new fragment
@Override
public void onItemSelected(int position) {

    if(position == 0) {

        getFragmentManager().beginTransaction()
                .replace(R.id.container, Example1_Fragment.newInstance(0))
                .addToBackStack(null)
                .commit();

    }
   ....
 }

 // In Example1_Fragment

public class Example1_Fragment extends Fragment {

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

    View view = inflater.inflate(R.layout.example1_fragment, container, false);

    Button btnIntent = (Button) view.findViewById(R.id.btnIntent);
    btnIntent.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            Intent intent = new Intent();
            intent.setAction("com.android.test2.app.example1_action");
            startActivityForResult(intent,1);
        }
    });

    return view;
}

// this is why I want to come back to Example1_Fragment - 
// the activity I start has to send a result back to
// the Example1_Fragment, but on back button, it takes me
// back to the ListFragment, and I cannot take any UI
// action (change to UI) in Example1_Fragment, as the
// ListFragment gets displayed - the onActivityResult of
// Example1_Fragment does get called

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);

    if(requestCode == 1 && resultCode == Activity.RESULT_OK){

             // do something
    }
}

Answer 1

不要替换onResume（）回调中的Fragment1，当您回到activity1时总会调用这个方法，请在onCreate（）回调中进行。