Is it a good idea to call finish() after starting a new Activity in Android?

android android-intent out-of-memory activity-finish
Marton_hun picture Marton_hun · Aug 7, 2013 · Viewed 13.1k times · Source

Like:

startActivity(intent);
finish();

Without calling finish() explicitly, onDestroy() is not called for the former Activity, and I run out of memory (OutOfMemory Exception).

So, is it a good idea to call finish() explicitly to prevent OutOfMemory Exception?

Answer

Ted Hopp picture Ted Hopp · Aug 7, 2013

When you start a new activity, the current activity is pushed onto the back stack of the current task. (You can change this behavior via flags and/or the manifest, but this is the default behavior.) When the user presses the back function, the top activity is finished and the stack is popped. The result is that the user sees the app return to the previous activity.

It's perfectly fine to call finish() after starting a new activity. The result will be that the current activity (which is no longer at the top of the stack, since you just started a new one) will be removed from the stack. Then when the user presses Back, it will go to the previous activity on the back stack (or exit your app if the stack is empty).

If you are bouncing back and forth between, say, activities A and B by always starting a new one and never calling finish(), this can cause an OOM exception as the stack fills up with instances of each activity.

You can read more about this in the guide topic Tasks and Back Stack. It also describes how to deal correctly with cycling between activities.

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