Android thread Communication

Reference: http://codinghard.wordpress.com/2009/05/16/android-thread-messaging/

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Source code:

 Package  Sample. thread. messaging;  Import  Android. App. activity;  Import  Android. OS. Bundle;  Import  Android. OS. Handler;  Import  Android. OS. logoff;  Import  Android. OS. message;  Import Android. util. log;  Import  Android. View. view;  Import  Android. View. View. onclicklistener;  Import  Android. widget. Button;  Import  Android. widget. textview;  /**  *  @ Author  David Kuo *  */  Public   Class Threadmessaging Extends  Activity {  Private   Static   Final String tag = "threadmessaging" ;  Private  Textview mtextview;  Private  Handler mmainhandler, mchildhandler;  /**  Called when the activity is first created.  */  @ Override Public   Void  Oncreate (bundle savedinstancestate ){  Super  . Oncreate (savedinstancestate); setcontentview (R. layout. Main); mtextview = (Textview) findviewbyid (R. Id. Text );  /*  * Create the main handler on the main thread so it is bound to the main * thread's message queue.  */  Mmainhandler = New Handler (){  Public   Void  Handlemessage (Message MSG) {log. I (tag, "Got an incoming message from the Child thread-" + (String) msg. OBJ );  /*  * Handle the message coming from the Child thread.  */  Mtextview. settext (mtextview. gettext () + (String) msg. OBJ + "\ n" );}}; /*  * Start the child thread.  */          New  Childthread (). Start (); log. I (tag, "Main handler is bound to-" + Mmainhandler. getlooper (). getthread (). getname (); button = (Button) findviewbyid (R. Id. Button); button. setonclicklistener (  New  Onclicklistener () {@ override  Public   Void Onclick (view v ){  /*  * We cannot guarantee that the mchildhandler is created * in the Child thread by the time the user clicks the button.  */                  If (Mchildhandler! = Null  ){  /*  * Send a message to the Child thread.  */  Message msg =Mchildhandler. obtainmessage (); msg. OBJ = Mmainhandler. getlooper (). getthread (). getname () + "says hello" ; Mchildhandler. sendmessage (MSG); log. I (tag, "Send a message to the Child thread-" + (String) msg. OBJ) ;}}) ;}@ override  Protected   Void  Ondestroy () {log. I (tag, "Stop looping the child thread's message queue" );  /*  * Remember to stop the Logoff */  Mchildhandler. getlooper (). Quit ();  Super  . Ondestroy ();}  Class Childthread Extends  Thread {  Private   Static   Final String inner_tag = "childthread" ;  Public   Void  Run (){ This . Setname ("child" );  /*  * You have to prepare the loginbefore creating the handler.  */  Logoff. Prepare ();  /*  * Create the child handler on the Child thread so it is bound to the * child thread's message queue.  */  Mchildhandler = New Handler (){  Public   Void  Handlemessage (Message MSG) {log. I (inner_tag, "Got an incoming message from the main thread-" + (String) msg. OBJ );  /*  * Do some expensive operation there. For example, you need * to constantly send some data to the server.  */                      Try  { /*  * Mocking an expensive operation. It takes 100 MS to * complete.  */  Sleep ( 100 );  /*  * Send the processing result back to the main thread.  */  Message tomain = Mmainhandler. obtainmessage (); tomain. OBJ = "This is" + This . Getlooper (). getthread (). getname () + ". Did you send me \" "+ (string) msg. OBJ + "\"? " ; Mmainhandler. sendmessage (tomain); log. I (inner_tag, "Send a message to the main thread-" + (String) tomain. OBJ );}  Catch  (Interruptedexception e ){  //  Todo auto-generated Catch Block E. printstacktrace () ;}}; log. I (inner_tag, "Child handler is bound to-" + Mchildhandler. getlooper (). getthread (). getname ());  /*  * Start looping the message queue of this thread.  */  Logoff. Loop ();}}} 

 

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