如何从活动的片段返回到viewpager中的片段

Question

I have a viewpager with 2 fragments(A and B) in MainActivity . In the fragments in viewpager , I have a recyclerView for each fragment that contains a list of items. When I click on an item of a fragment viewpager , it displays a new Activity with a new fragment (C) on it. But when I press the back button on toolbar, it always went back to the MainActivity with fragment A of viewpager , even if I click on item of fragment B.

In androidManifest.xml , I added "parentActivity: MainActivity" to the new Activity. If I don't set that, the back button would not response. I need help to go back to the correct fragment when I press back button.

I appreciate all answers.

Answer 1

Very easy. Keep an index variable in your activity in which viewpager and fragments are loaded. When you switch to another activity, do it via this activities method and update that variable with the index of the current selected page/fragment in viewpager by

getCurrentItem

This method will return the index which you can store then there are two options for you: If you know that your activity is going to be resumed from that activity only then you can write below method in onResume:

setCurrentItem

Or else you can go for startActivityForResult and achieve the same. Let me know if any queries.

Answer 2

First of all let assume you pressed something to open C fragment from B fragment. Here you need to pass some value to inform that C was opened from B fragment.

Send data from fragment to activity

Intent intent = new Intent(getActivity().getBaseContext(),
                    TargetActivity.class);
            intent.putExtra("B", message);
            getActivity().startActivity(intent);

Here value "B" means that activity with fragment C is opened by fragment B. For A fragment you need to change it to "A" or whatever you want.

Receive data in activity and send it back if Back button pressed

    Intent intent = getIntent();
    String message = intent.getStringExtra("message");
    back.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(SecondActivity.class, FirstActivity.class)
                intent.putString(message)
            }
        });

Receive data in FirstActivity and set necessary page

Intent intent = getIntent();
String message = intent.getStringExtra("message");
if(message == "B"){
    viewPager.setCurrentItem(1) //1 is index of your second page 
}else {
    viewPager.setCurrentItem(0)
}

Try this code and let me know if something goes wrong

Answer 3

First, for going to "NewActivity" just start the activity using intent and not finish the "MainActivity" .

And For coming back to "MainActivity", just finish the "NewActivity"... hopefully, this will work!