29&30认识UI Thread.doc

上课讲义摘录之29/30: 认识UI Thread(1/2)
在前面的三篇讲义摘录里:
第1篇— Android的Message Queue(1/3)
第2篇— Android的Message Queue(2/3)
第3篇— Android的Message Queue(3/3)
介绍过Android主线程与子线程之沟通。所谓主线程通常是UI线程。Android的UI是单线程(Single-threaded)的。为了避免拖住GUI,一些较费时的对象应该交给独立的线程去执行。如果幕后的线程来执行UI对象,Android就会发出错误讯息
CalledFromWrongThreadException
例如下述范例:
//----- Looper_05范例-----
.;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
public class ac01 extends Activity implements OnClickListener {
private final int WC = ;
private final int FP = ;
public TextView tv;
private myThread t;
private Button btn, btn2;
private Handler h;
private Context ctx;
public void onCreate(Bundle icicle) {
(icicle);
ctx = this;
LinearLayout layout = new LinearLayout(this);
();

btn = new Button(this);
(101);
();
("test looper");
(this);
param =
new (100,50);
= 10;
(btn, param);

btn2 = new Button(this);
(102);
();
("exit");
(this);
(btn2, param);

tv = new TextView(this);
();
("");
param2 =
new (FP, WC);
= 10;
(tv, param2);
setContentView(layout);
//------------------------
t = new myThread();