2 ways to update the UI interface for child threads

In general, we will do some time-consuming operations on the child threads.

1, Android message mechanism:

2, Knowledge points:

Message: Messages that contain the message ID, the message Processing object, and the processed data are queued by MessageQueue and processed by handler.
Handler: Handler, responsible for sending and processing the message. When using handler, you need to implement the Handlemessage (Message msg) method to process a specific message, such as updating the UI.
MessageQueue: Message Queuing, which holds messages sent by handler and executes according to FIFO rules. Of course, storing a message is not a meaningful preservation, but rather a concatenation of the message in the form of a linked list, waiting for the looper to be extracted.
Looper: The message pump continuously extracts message execution from the MessageQueue. Therefore, a MessageQueue needs a looper.
Thread: Threads that are responsible for dispatching the entire message loop, that is, the execution site of the message loop.

Child Threads Update UI interface method One: with handler

1, we will be in the case of the previous Asynctask operation, we will click the call event in the previous call method comment.

 Public classMainactivityextendsActivity {PrivateSimpleadapter sa; PrivateButton btn; PrivateTextView TV; PrivateList<userinfos> list=NewArraylist<userinfos>(); PrivateBaseadapter Adapter; PrivateListView LV; PrivateRunnable DoInBackground1; PrivateRunnable DoInBackground2; PrivateRunnable DoInBackground3; PrivateHandler Handler; PrivateThread th; PrivateThread Th2; @Overrideprotected voidonCreate (Bundle savedinstancestate) {//here is the main thread of the UI        Super. OnCreate (savedinstancestate);        Setcontentview (R.layout.activity_main);  for(inti = 0; I < 5; i++) {Userinfos u=NewUserinfos (); U.setname ("Xiao Ming" +i); U.setsex ("Male" +i);        List.add (U); } LV= (ListView) This. Findviewbyid (R.id.listview1); TV=(TextView) Findviewbyid (R.ID.TEXTVIEW1); BTN=(Button) Findviewbyid (R.id.button1); Btn.setonclicklistener (NewOnclicklistener () {//analog data access generates data@Override Public voidOnClick (View v) {//TODO auto-generated Method Stub                /*Take tk=new take (mainactivity.this);//Sync Task Tk.execute (list,adapter);//parameter is passed to Doinbackground*/               thread t1=new thread (DOINBACKGROUND1);                T1.start ();                Thread t2=new thread (DOINBACKGROUND2);                T2.start ();                Thread t3=new thread (DOINBACKGROUND3); T3.start ();            }});

Handler=NewHandler () { Public voidhandlemessage (android.os.Message msg) {intwhat=Msg.what; LOG.I ("Handler", "has received the message, message what:" +what+ ", ID:" +Thread.CurrentThread (). GetId ()); if(what==1) {log.i ("Handler has received the message", "" +what ); Tv.settext ("Child Thread One"); }                     if(what==2) {log.i ("Handler has received the message", "" +what );                                             Adapter.notifydatasetchanged (); }                     if(what==3) {log.i ("Handler has received the message", "" +what );                         Adapter.notifydatasetchanged (); Btn.settext ("Child thread Three");             }                 }; };             //Child thread One            doinbackground1=new Runnable () {@Override public void run () {//TOD                    O auto-generated Method Stub try {thread.sleep (3000);                        } catch (Interruptedexception e) { //TODO auto-generated catch block                    E.printstacktrace (); }1. Access to the database or the Internet, not the UI process, so no cardmessage Msg=new message ();An identification number for the message, which makes it easy for handler to recognizemsg.what=1;                    Handler.sendmessage (msg); LOG.I ("DD", "sub-line Cheng has sent a message to handler");}}; Sub-thread TwoDoinbackground2=new Runnable () {@Override public void run () {                        TODO auto-generated Method Stub try {thread.sleep (5000);                            } catch (Interruptedexception e) {//TODO auto-generated catch block                        E.printstacktrace ();                        } message Mge=new message ();                        mge.what=2;                         Handler.sendmessagedelayed (mge,200);                         for (Userinfos us:list) {us.setname ("Lili");                                        } log.i ("DD", "sub-line Cheng sent a message to handler"); }};//Sub-line ChengDoinbackground3=new Runnable () {@Override public void Ru                                N () {//TODO auto-generated method stub try {                            Thread.Sleep (9000);                                } catch (Interruptedexception e) {//TODO auto-generated catch block                            E.printstacktrace ();                            } message Mge=new message ();                            mge.what=3;                             Handler.sendmessagedelayed (mge,200);                             for (Userinfos us:list) {us.setsex ("female");                                                    } log.i ("DD", "sub-line Cheng sent a message to handler"); }};

1, the child thread sends the message, notifies handler to complete the UI update:

2, Handler the Handlemessage method carries on the message processing, receives the message to carry on the UI interface update.

Note: The handler object of method one must be defined in the main thread, and if multiple classes are called directly to each other, it is not very convenient to pass a Content object or call through an interface.

：

Child thread Update UI interface method Two: update with the Runonuithread method of the Activity object

UI Update via the Runonuithread method

 Public void OnClick (View v) {                //  TODO auto-generated method stub/                *taketk=new Take (mainactivity.this);//Synchronous Task                Tk.execute (list,adapter);//parameter is passed to Doinbackground*                / /*thread t1=new thread (DOINBACKGROUND1);                T1.start ();                Thread t2=new thread (DOINBACKGROUND2);                T2.start ();                Thread t3=new thread (DOINBACKGROUND3);                T3.start (); */                 Th.start ();                Th2.start ();            }});

Th=NewThread () {@Override Public voidrun () {//Here is the time-consuming operation, updating the UI after completion;Runonuithread (NewRunnable () {//Update UI@Override Public voidrun () {//TODO auto-generated Method StubBtn.settext ("Runonuithread Child thread One");                    }                                            }); Super. Run ();             }             }; Th2=NewThread () { Public voidrun () {Runonuithread (NewRunnable () {@Override Public voidrun () {Try{Thread.Sleep (3000); } Catch(interruptedexception e) {//TODO auto-generated Catch blockE.printstacktrace (); }                            //TODO auto-generated Method StubTv.settext ("Runonuithread sub-thread Two");                 }                                              });                              }; };

1, through the Runonuithread method new a runnable implementation of the Run method UI interface update.

If it is in a non-contextual class (Activity), it can be invoked by passing the context;

Chip

2 ways to update the UI interface for child threads