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This article mainly introduces the relevant knowledge of "what is the role of Handler in Android". Xiaobian shows you the operation process through actual cases. The operation method is simple, fast and practical. I hope this article "what is the role of Handler in Android" can help you solve the problem.

Android Handler details

Handler is often used to inform the main thread to do the corresponding operation, but if not only will cause memory leakage, so write the correct handler.

Handler handler = new Handler() { public void handleMessage(Message msg) { //do something }; };handler.sendEmptyMessageDelayed(0, 100 * 1000);

Like the code snippet above, there is a risk of a memory leak because the handler hogging references to Acitvity prevents the system from performing GC collection operations.

private static class MyHandler extends Handler { WeakReference mWeakReferenceActivity; public MyHandler(MainActivity activity) { mWeakReferenceActivity = new WeakReference(activity); } @Override public void handleMessage(Message msg) { super.handleMessage(msg); if (null != mWeakReferenceActivity) { MainActivity _activity = mWeakReferenceActivity.get(); //_activity.dosomething(); } } }

The correct approach is to store the Activity in WeakReference, so that WeakReference will not prevent the system from recycling when the Activity ends, which can effectively avoid the risk of memory leakage caused by the handler.

Of course, it is not impossible for you to write handler, you need to handle.removeCallbacksAndMessages(null) at the end of the Activity; so that the system can perform the recovery operation normally.

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