问题
Say I have 3 Activities in my application: A, B and C. The flow though the application is: A -> B -> C.
Once at C, pressing the back button will take the user to B. If the user presses the back button another time they got to A, and finally if they press it one more time, they exit the application.
Objective: When the user presses the back button on C, they should go to A and not B, and if they press it another time, they exit the app.
Problem: When overriding the back button on Activity C to launch Activity A everything appears to be ok. However if the user presses the back button again, they return to Activity C. And so pressing the back button just switches between Activity A and Activity C.
I guess the Activity stack looks like:
- Open app: A
- Go to B: A, B
- Go to C: A, B, C
- Press back: A, B, C, A
- Press back: A, B, C
- Press back: A, B, C, A
- Press back: A, B, C
- Press back: A, B, C, A
- Press back: A, B, C
- Press back: A, B, C, A
- ...etc
So it seems the mistake is to launch a new Activity when the back button on C is pressed? Anyway, I could do with advice on how to implement this behaviour.
Thanks, Jack
回答1:
You can add finish() in the onStop() method of activity B.
This way, when the activity B will no longer be visible, it will be destroyed and removed from the stack.
- Open app: A
- Go to B: A, B
- Go to C: A, C
- Press back: A
- Press back: exiting
回答2:
When you go Activity B to Activity C first finish activity B then go activity C.
ex:-
finish();
Intent i2 = new Intent(Acttivity.B, Acttivity.C);
startActivity(i2);
来源：https://stackoverflow.com/questions/6609045/android-back-button-problem