返回活动的片段

Question

I have an activity (MainActivity) which has a navigation drawer and can show 2 fragments (Fragments A and B), one at a time. (This activity is the default activity with navigation drawer created by android studio)

When I choose fragment B on the drawer the action bar menu is updated to show a button specific for fragment B (Button P).

Button P open an independent activity (IndependentActivity) with an explicit intent, on this activity I perform a database operation and after it I finish this activity to go back to MainActivity.

The problem is: When IndependentActivity is finished, MainActivity is shown but it shows fragment A instead of fragment B which was the one that called the intent to go to IndependentActivity.

How do I fix this by showing the fragment that initiated the action to go to another activity? Is there any way to save the fragment that was appearing?

Answer 1

Basically what you have to do is:

• Save the state of the MainActivity when you enter IndependentActivity
• Reload the state of MainActivity when you exit IndependentActivity

A simple implementation of this could be:

@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
    // Save which fragment that is in the view when entering another activity
    savedInstanceState.putString("fragment", "fragmentB");
    super.onSaveInstanceState(savedInstanceState);
}

Fragment B can be replaced with a string that tells the application which is the current fragment.

Once you come back to the activity you want to:

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    if( savedInstanceState != null ) {
         // Get which fragment that was active when you left the activity
         savedInstanceState.getString("fragment");

         // Programatically select the fragment here
    }
}

You can read more about saving instance state here:

http://developer.android.com/training/basics/activity-lifecycle/recreating.html

I will leave it to you to programmatically select the fragment. I hope it helps!

Answer 2

I found out that I was having the same problem as this: https://stackoverflow.com/a/29464116/2325672

The back arrow to return did not work and reset the activity's fragments and the emulator back triangle worked perfectly.

Adding this code to IndependentActivity worked for me:

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    if (item.getItemId()== android.R.id.home) {
        Intent intent = NavUtils.getParentActivityIntent(this);
        intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        NavUtils.navigateUpTo(this, intent);
        return true;
    }
    return super.onOptionsItemSelected(item);
}