按下时，Android Intent FLAG_ACTIVITY_TASK_ON_HOME不会返回首页

Question

I have a Chat app with this situation:

A - MainActivity

B - Chat activity

C - Forward activity

Let's assume i want to forward a message from Bill to John's chat, i open A -> B -> C, on C i must select the user to forward, so i click on John throwing a new B intent, now in the stack i have ABCB, if from John's chat i press the back button i want to go back in A (MainActivity), but actually i go back in B (Bill's chat), this is a problem because the Chat activity must be only one. For necessity the Chat activity is set as android:launchMode="singleTop" in the manifest, because if i have a Chat in foreground and i click on "new message" android notification, the current Chat is closed and the new one is opened. Reading on developers guide i've found FLAG_ACTIVITY_TASK_ON_HOME, as i can understand with this flag i should be able to back directly from John's chat(B) to MainActivity(A) but doesn't happens.

This is A (MainActivity with sliding tab layout, the Intent is launched from ListFragment Tab activity)

    Intent intent = new Intent(getContext(), Chats.class);
    Bundle b = new Bundle();
    b.putString("nid", list_id.toString()); 
    b.putString("user_id_key", list_user_id.toString());
    b.putString("name", list_name.toString());
    b.putString("number", list_number.toString());
    intent.putExtras(b); 
    startActivityForResult(intent, 101);

This is B (Chat activity - AppCompatActivity)

    Intent intent = new Intent(getApplicationContext(), Forward.class);
    intent.addFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
    Bundle b = new Bundle();
    b.putString("forward_mess", MessText);
    b.putString("number", number);
    b.putString("conv_id", convId);
    intent.putExtras(b);
    startActivity(intent);

This is C (Forward activity - AppCompatActivity)

    Intent intent = new Intent(getApplicationContext(), Chats.class);
    intent.addFlags(Intent.FLAG_ACTIVITY_TASK_ON_HOME);
    Bundle b = new Bundle();
    b.putString("nid", sel_nid);
    b.putString("user_id_key", sel_user_receiver);
    b.putString("name", sel_name);
    b.putString("number", sel_number);
    b.putString("forward_mess", forward_mess);
    intent.putExtras(b);
    startActivityForResult(intent, 101);
    finish();

Also tried with FLAG_ACTIVITY_CLEAR_TOP, but this brings me directly to A->B

Answer 1

Solved using onActivityResult method in Chat activity.

Here the correct activities flow:

MainActivity -> startActivityForResult(chat_intent, 101);

Chat -> startActivityForResult(forward_intent, 5);

Set the onActivityResult method:

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    //If is 5 means Forward activity was closed
    if (requestCode == 5) {
        // If 10 means a new Chat was opened, so this one must be closed
        if (resultCode == 10) {
            finish();
        }
    }
}

Forward

startActivityForResult(chat_intent, 101);
setResult(10);
finish();