活动处于活动状态时的Android后台操作

Question

So this is my theory - when creating a background thread on activity creation, with a callback that references by the activity, if activity closed, it stays in memory because of the hard reference of the callback, am I right? So how can I make sure the background operation stop's it's execution when activity closed?

Answer 1

让你的Activity实现onStop()并在那时杀死你的后台任务。

Answer 2

Do you want onStop() or onDestroy() ?

Navigating away from the Activity, such as clicking a list item or starting a subactivity will trigger onPause() , then onStop() when the activity is fully invisible. If memory is your concern, you should look into implementing it in onDestroy() and/or use a Weak/SoftReference in the background operation to prevent leakage.

Answer 3

When an Activity is finished, android sets all its view references to null and then the Activity reference is set to null. Also, Android assumes that the threads started by the Activity could be killed with no problems. So, the threads would get killed but the time is not defined. In you situation a callback wont matter as all the references would be set to null. Ther would be nobody to listen to callback.

The easiest to kill your threads yourself is to keep the code execution of the thread in a loop.You can have a volatile boolean parameter that is checked on every loop of your thread:

while (!threadStop) {
    // Do stuff
}

In onDestroy(), make this variable as true