The difference between Android finish and System.exit (0)

Finish is the activity class, only for the activity, when the call to finish (), only the activity pushed to the background, and did not immediately release memory, the active resource is not cleaned up, when called System.exit (0), the entire process was killed,

The resources of the activity will also be released.

In the development of Android applications, often by pressing the return key (ie keycode = = Keyevent.keycode_back) can close the program, in fact, most of the time the application is still running in the task, in fact, this is not the result we want.

We can do this, when the user clicks on the Custom Exit button or return key (need to capture the action), we force exit the application in OnDestroy () , or kill the process directly.