Simple use of Android Handler and loops

1. Communication between child threads and sub-threads

Package Lib.com.myapplication;import Android.os.bundle;import Android.os.handler;import android.os.Looper;import Android.os.message;import Android.support.v7.app.appcompatactivity;public class Mainactivity extends    appcompatactivity {private Handler handler1;    Private Handler Handler2;        @Override protected void OnCreate (Bundle savedinstancestate) {super.oncreate (savedinstancestate);        Setcontentview (R.layout.activity_main);        New MyThread1 (). Start ();    New MyThread2 (). Start ();            } class MyThread1 extends Thread {@Override public void run () {super.run ();            Looper.prepare ();                    Handler1 = new Handler () {@Override public void Handlemessage (Message msg) {                    Super.handlemessage (msg);                System.out.println ("threadname--" + thread.currentthread (). GetName () + "messagewhat-" + msg.what);            }            };                try {Sleep (3000);            } catch (Interruptedexception e) {e.printstacktrace ();            } handler2.sendemptymessage (2);        Looper.loop ();            }} class MyThread2 extends Thread {@Override public void run () {super.run ();            Looper.prepare ();                    Handler2 = new Handler () {@Override public void Handlemessage (Message msg) {                    Super.handlemessage (msg);                System.out.println ("threadname--" + thread.currentthread (). GetName () + "messagewhat-" + msg.what);            }            };            try {sleep (4000);            } catch (Interruptedexception e) {e.printstacktrace ();            } handler1.sendemptymessage (5);        Looper.loop (); }    }}

　　

Attention:

1. Call the method of the Looper class to prepare() create a message loop for the current thread, calling the loop() method to process the information until the loop ends.

2. Handler has several construction overloads that, if constructed without a Looper class object parameter, gets the Looper object of the current thread , which is the message loop of the current thread as the handler association.

3. in the message processing mechanism, the message is stored in a message queue, and the thread enters an infinite loop around the queue until the program exits.

　　If there is a message in the queue, the thread will take the message out and distribute it to the appropriate handler for processing;

If there is no message in the queue, the thread enters the idle wait state and waits for the next message to arrive.

Simple use of Android Handler and loops