Android_handler (b)

Tag: Send message file message take Out star thread TCO pop effect

This article records the Android message mechanism. Workthread simulates a step in which a message is sent to Mainthread and changes the text of TextView after the data is obtained from the network. (Mainthread←workthread).

Steps:
1. Create a handler object in Mainthread. The replication Handlemessage () method.
2. Workthread calls the SendMessage () method of Handermessage () to send a message to the message queue
3, Looper in the message queue to remove the message object, to Mainthread handlemessage () method processing.

Code:

Layout

<textview         android:id= "@+id/textviewid"        android:layout_width= "match_parent"        android:layout_ height= "Wrap_content"        android:text= "Data"/>        <button        android:id= "@+id/buttonid"        android: Layout_width= "Match_parent"        android:layout_height= "wrap_content"        android:layout_below= "@id/textviewid"        android:text= "Send Message"/>

activity:

Package Com.away.b_07_handler02;import Android.app.activity;import Android.os.bundle;import Android.os.Handler; Import Android.os.message;import Android.view.view;import Android.view.view.onclicklistener;import Android.widget.button;import Android.widget.textview;public class Mainactivity extends Activity {private TextView Textview;private Button button;private Handler Handler; @Overrideprotected void OnCreate (Bundle savedinstancestate) { Super.oncreate (savedinstancestate); Setcontentview (r.layout.activity_main); TextView = (TextView) Findviewbyid ( R.ID.TEXTVIEWID); button = (button) Findviewbyid (r.id.buttonid); handler = new MyHandler (); Button.setonclicklistener ( New Buttonlistener ());} Class MyHandler extends Handler {@Overridepublic void Handlemessage (Message msg) {System.out.println ("handlermessage-- -->>: "+ thread.currentthread (). GetName ()); string s = (string) msg.obj;textview.settext (s);}} Class Buttonlistener implements Onclicklistener {@Overridepublic void OnClick (View arg0) {threAd t = new Networkthread (); T.start ();}} Class Networkthread extends Thread {@Overridepublic void run () {System.out.println ("network---->>:" + Thread.curr Entthread (). GetName ());//analog access to the network, so that when the thread sleeps, first sleep for 2 seconds try {thread.sleep (2 *);} catch (Interruptedexception e) { E.printstacktrace ();} The value of the variable s, which simulates the data obtained from the network as a string s = "Data obtained from the network";//Textview.settext (s); Such a practice is wrong, due to the fact that in Android systems, there are only mainthread which have the ability to operate uimessage msg = Handler.obtainmessage (); msg.obj = s;//sendMessage () method, Whether it is sent in the main thread or workers thread, it is capable of handler.sendmessage (msg);}}

Effect:

Welcome to AC http://blog.csdn.net/ycwol/article/details/42066449

Android_handler (b)