How Does Android Manage Background Threads When Exiting an Activity?

What happens to background threads when an Android Activity is exited?

In Android development, managing background threads is crucial for ensuring a smooth user experience, particularly when transitioning between activities. When an Activity is exited, background threads associated with that Activity need proper management to avoid memory leaks and ensure optimal performance.

private class MyAsyncTask extends AsyncTask<Void, Void, Void> {
   @Override
   protected void onPreExecute() {
       // Prepare for task
   }
   @Override
   protected Void doInBackground(Void... voids) {
       // Background task
       return null;
   }
   @Override
   protected void onPostExecute(Void aVoid) {
       // Handle result
   }
}

@Override
protected void onStop() {
    super.onStop();
    if (myAsyncTask != null) {
        myAsyncTask.cancel(true);
    }
}

Causes

• When an Activity is closed or exited, its lifecycle events are triggered, impacting running threads.
• Unfinished background tasks can continue running or get abruptly terminated based on how they are implemented.

Solutions

• Utilize AsyncTasks or Executors tied to the Activity lifecycle to manage threads more effectively.
• Implement the onPause() and onStop() lifecycle methods to cancel or finish background operations when the Activity is no longer visible.
• Use Services for long-running tasks that need to continue after an Activity is exited.

Mistake: Forgetting to manage AsyncTasks or threads in Activity lifecycle methods.

Solution: Always handle thread termination in onPause() or onStop() to avoid memory leaks.

Mistake: Using static references to Activities within threads, causing leaks.

Solution: Use WeakReferences or ensure to nullify references to avoid memory leaks.