求救,多线程中遇到的问题!!!

Question

以下是我的程序:
package threadtest2;import java.awt.BorderLayout;
import java.awt.Dimension;import javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.TextArea;
import java.awt.*;/**
 * <p>Title: ThreadTest2</p>
 *
 * <p>Description: </p>
 *
 * <p>Copyright: Copyright (c) 2005</p>
 *
 * <p>Company: </p>
 *
 * @author not attributable
 * @version 1.0
 */
public class ThreadTest3 extends JFrame {
    JPanel contentPane;
    BorderLayout borderLayout1 = new BorderLayout();
    TextArea textArea1 = new TextArea();    public ThreadTest3() {
        try {
            setDefaultCloseOperation(EXIT_ON_CLOSE);
            jbInit();
        } catch (Exception exception) {
            exception.printStackTrace();
        }
    }    /**
     * Component initialization.
     *
     * @throws java.lang.Exception
     */
    private void jbInit() throws Exception {
        contentPane = (JPanel) getContentPane();
        contentPane.setLayout(borderLayout1);
        setSize(new Dimension(400, 300));
        setTitle("Frame Title");
        class DemoThread implements Runnable{
            String name;
            Thread t;
            DemoThread(String Name_of_Thread){
                name=Name_of_Thread;
                t=new Thread(this.name);
                textArea1.append("New thread:"+t+"\n");
                t.start();
            }
            public void  run(){
                try{
                    for (int i=4;i>0;i--){
                        textArea1.append(name+":"+i+"\n");
                        Thread.sleep(1000);
                    }
                }catch(InterruptedException e){
                    textArea1.append(name + "interuupted.\n");
                }
                textArea1.append(name +"exied.\n");
            }        }
        DemoThread th1=new DemoThread("one");
        DemoThread th2=new DemoThread("two");
       
        textArea1.append("Thread one is alive:"+th1.t.isAlive()+"\n");
        textArea1.append("Thread two is alive:"+th2.t.isAlive()+"\n");
        try{
            textArea1.append("waiting for threads to finish.\n");
            th1.t.join();
            th2.t.join();
        }
        catch(InterruptedException e){
            textArea1.append("Main thread interrupted\n");
        }
        textArea1.append("Thread one is alive:"+th1.t.isAlive()+"\n");
        textArea1.append("Thread two is alive:"+th2.t.isAlive()+"\n");
        textArea1.append("Main thread exited.");        contentPane.add(textArea1, java.awt.BorderLayout.CENTER);
    }
}
但我不知道为什么它可以执行到t.start(),但就是进不了 run(),请高手们帮帮忙~~~~~~~~~

Answer 1

t.start()不能在构造器中调用. 用下法即可:
DemoThread th1=new DemoThread("one");
DemoThread th2=new DemoThread("two");
new Thread(th1).start();另外,为什么不用extends Thread?至少可以不用Thread成员

Answer 2

从你的设计来看，这是一个自启动线程的设计，但设计有问题。
                t=new Thread(this.name);
                textArea1.append("New thread:"+t+"\n");
                t.start();
并没有启动你设计的线程。如果你想启动一个自定义的线程，应该用下面的方式启动。
                Thread t = new Thread(new 自定义线程());
                t.start();