How to navigate from fragment in one activity to fragment in another activity?

Question

I want to add back navigation to toolbar. I need to get from a fragment in an activity to a specific fragment in another activity.

It looks a little like this, where every orange line means navigating to a new activity or fragment:

How do I move from fragment B to fragment A from OtherActivity?

Answer 1

Consider these steps:

From Activity 1 holding Fragment A , you want to directly load Fragment B in Activity 2.

Now, I am thinking first, then you press a button in Fragment A, you can directly go to Activity B.

Then it means, you can simply load Fragment B as soon as you arrive in Activity 2.

Since you are dealing with back navigation (I believe you mean the upNavigation?), you can override the following:

But watch clearly, because if you need to load an exact fragment in Activity 2, you need to know somehow:

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {

        case android.R.id.home:
            Intent intent = new Intent(this, Activity2.class);
            intent.putExtra("frag", "fragmentB");
            startActivity(intent);
            return true;
        default:
            return super.onOptionsItemSelected(item);
    }

}

As you can see, when you click the back arrow on the toolbar, we pass a value through our intent to identity which fragment we want to load.

Next, in your Activity2, simply get the intent extra and do a switch or an if statement:

@Override
public void onResume(){
  super.onResume();

  Intent intent = getIntent();

  String frag = intent.getExtras().getString("frag");

  switch(frag){

    case "fragmentB":
       //here you can set Fragment B to your activity as usual;
        fragmentManager.beginTransaction().replace(R.id.container_body, new FragmentB()).commit();
       break;
  }
}

From here, you should have your Fragment B showing in Activity 2.

Now you can handle the same thing while inside Activity 2 to decide where to go when a user clicks the back home arrow!

I hope this helps you get an idea.

Note: I thought about the interface approach and realized it is not necessary since this can be done easily with this approach!