Android advanced tutorial (9)-How to Use Android handler !!!

Hello everyone, this section is about the use of Android handler. before talking about handler, let's raise a small question: how can the program update the title in five seconds. first, let's take a look at the Java programmers who are used to writing programs before they know how to use handler. The Code is as follows:

1. Package com. Android. tutor;
2. Import java. util. timer;
3. Import java. util. timertask;
4. Import Android. App. activity;
   
5. Import Android. OS. Bundle;
6. Public class handlerdemoextends activity {
8. // Title provides variables for the settitle method. I have set this variable to the int type for convenience.
9. Private int title = 0;
11. Public void oncreate (bundle savedinstancestate ){
12. Super. oncreate (savedinstancestate );
    
13. Setcontentview (R. layout. Main );
15. Timer timer = new timer ();
16. Timer. scheduleatfixedrate (New mytask (), 1,5000 );
17. }
19. Private class mytaskextends timertask {
20. @ Override
21. Public void run (){
23. Settitle ("welcome to Mr Wei's blog" + title );
24. Title ++;
25. }
26. }
27. }

Package COM. android. tutor; import Java. util. timer; import Java. util. timertask; import android. app. activity; import android. OS. bundle; public class handlerdemo extends activity {// Title provides variables for the settitle method. For convenience, I have set the int type private int title = 0; Public void oncreate (bundle savedinstancestate) {super. oncreate (savedinstancestate); setcontentview (R. layout. main); timer = new timer (); timer. scheduleatfixedrate (New mytask (), 1, 5000);} private class mytask extends timertask {@ overridepublic void run () {settitle ("welcome to Mr Wei's blog" + title); Title ++ ;}}}However, when we execute a program, we cannot achieve the expected results. Therefore, Android introduces the special class handler, which can be said to be a bridge between runnable and activity, therefore, we only need to send a message in the run method, and execute different tasks through different messages in handler. The modified code is as follows:

1. Package com. Android. tutor;
2. Import java. util. timer;
3. Import java. util. timertask;
4. Import Android. App. activity;
   
5. Import Android. OS. Bundle;
6. Import Android. OS. Handler;
7. Import Android. OS. message;
8. Public class handlerdemoextends activity {
10. // Title provides variables for the settitle method. I have set this variable to the int type for convenience.
11. Private int title = 0;
13. Private handler mhandler = new handler (){
15. Public void handlemessage (Message MSG ){
16. Switch (msg. What ){
17. Case 1:
18. Updatetitle ();
19. Break;
20. }
21. };
22. };
23. Public void oncreate (bundle savedinstancestate ){
24. Super. oncreate (savedinstancestate );
    
25. Setcontentview (R. layout. Main );
27. Timer timer = new timer ();
28. Timer. scheduleatfixedrate (New mytask (), 1,5000 );
29. }
31. Private class mytaskextends timertask {
32. @ Override
33. Public void run (){
35. Message message = new message ();
36. Message. What = 1;
37. Mhandler. sendmessage (Message );
39. }
40. }
43. Public void updatetitle (){
45. Settitle ("welcome to Mr Wei's blog" + title );
46. Title ++;
47. }
48. }