线程同步的问题，急！！！

Question

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;public class ProgressBar implements ActionListener
 {
JFrame frame=null;
JProgressBar progressbar;
JLabel label;
JButton b;
MyThread thread;
private int len = 20;
private int size = 100;
private int value = 0;
private boolean doing = true;
public ProgressBar()
{
   frame=new JFrame("安装");
   frame.setBounds(100, 100, 400, 130);
   frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   Container contentPanel=frame.getContentPane();
   label=new JLabel("",JLabel.CENTER);
   progressbar = new JProgressBar();
   progressbar.setOrientation(JProgressBar.HORIZONTAL);
   progressbar.setMinimum(0);
   progressbar.setMaximum(100);
   progressbar.setValue(0);
   progressbar.setStringPainted(true);
   progressbar.setPreferredSize(new Dimension(300,20));
   progressbar.setBorderPainted(true);
   progressbar.setBackground(Color.pink);
  
   thread = new MyThread();
   JPanel panel=new JPanel();
   b=new JButton("安装");
   b.setForeground(Color.blue);
   b.addActionListener(this);
   panel.add(b);    contentPanel.add(panel,BorderLayout.NORTH);
   contentPanel.add(progressbar,BorderLayout.CENTER);
   contentPanel.add(label,BorderLayout.SOUTH);
  
   frame.setVisible(true);
}
public void actionPerformed(ActionEvent e)
{
   if(e.getSource()==b)
   {
thread.start();
value += len/(float)size*100;
System.out.println("...."+value);
   }

}
//线程类
public class MyThread extends Thread
{
public MyThread()
{
}

public void run()
{
while(doing)
{
progressbar.setValue(value);
}
}
}
public static void main(String[] args) 
{
   ProgressBar app=new ProgressBar();
}
}
代码如上，程序很简单，就是单击按钮，进度条显示相应进度，由于进度条的进度值是在单击按钮后实时更新的，所以要实现同步更新，但现在问题是不知道怎么写了，刚开始学习线程，所以不太明白，请大家帮帮忙，指导一下

Answer 1

for example
public class MyThread extends Thread
{
    JProgressBar pb;
    int step;
    public MyThread(JProgressBar pb, int step)
    {
        this.pb = pb;
        this.step = step;
    }    public void run()
    {
        while(true)
        {
            int value = pb.getValue();
            if (value == pb.getMaximum()) break;
            value += step;
            pb.setValue(value);
            System.out.println("...."+value);            try {
                sleep(1000);
            } catch (Exception e) {}
        }
    }
}thread = new MyThread(); -> thread = new MyThread(progressbar, len*100/size);public void actionPerformed(ActionEvent e)
{
    if(e.getSource()==b)
    {
        if (thread.getState() == Thread.State.NEW) {
            thread.start();
        }
        //value += len/(float)size*100;
        //System.out.println("...."+value);
    }
}

Answer 2

谢谢，不过问题是 value += step;这个步骤是在 if(e.getSource()==b){}这个里面啊，并不是让另一线程自动更新，而是要让另一个线程先获得主线程的value值，然后再更新，value变一次，更新一次,应该是要用到同步，但还是不知道怎么写

Answer 3

你的意思是两个线程，一个线程更新value，一个线程刷新进度条，是这个意思吧
for example
public class MyThread extends Thread
{
    JProgressBar pb;
    int step;
    int id;
    static int value = 0;
    public MyThread(JProgressBar pb, int step, int id)
    {
        this.pb = pb;
        this.step = step;
        this.id = id;
    }    public void run()
    {
        while(true)
        {
            synchronized (pb) {
                try {
                    if (id == 0) { //如果是负责增加value的线程
                        while (value != pb.getValue()) { //判断value是否已经更新过
                            pb.notifyAll();
                            pb.wait(); //更新过则唤醒其他线程，然后自己等待
                        }
                        value += step;
                        System.out.println("update value...."+value);
                    } else { //如果是负责刷新进度条的线程
                        while (value == pb.getValue()) { //判断是否已经刷新过
                            pb.notifyAll();
                            pb.wait(); //刷新过则唤醒其他线程，然后自己等待
                        }
                        pb.setValue(value);
                        System.out.println("refresh progressbar...."+value);
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                } finally {
                    pb.notifyAll(); //最后唤醒其他线程
                }                if (value == 100) {break;} //进度条达到最大，则退出循环
            }
            yield();
        }
    }
}定义两个线程
MyThread thread1,thread2;thread = new MyThread(); -> 
thread1 = new MyThread(progressbar, len*100/size, 0);
thread2 = new MyThread(progressbar, len*100/size, 1);public void actionPerformed(ActionEvent e)
{
    if(e.getSource()==b)
    {
        if (thread1.getState() == Thread.State.NEW) {
            thread1.start();
        }
        if (thread2.getState() == Thread.State.NEW) {
            thread2.start();
        }
        //value += len/(float)size*100;
        //System.out.println("...."+value);
    }
}

Answer 4

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;public class ProgressBar implements ActionListener
 {
JFrame frame=null;
JProgressBar progressbar;
JLabel label;
JButton b;
MyThread thread;
private int len = 20;
private int size = 100;
private int value = 0;
private boolean doing = true;
public ProgressBar()
{
frame=new JFrame("安装");
frame.setBounds(100, 100, 400, 130);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Container contentPanel=frame.getContentPane();
label=new JLabel("",JLabel.CENTER);
progressbar = new JProgressBar();
progressbar.setOrientation(JProgressBar.HORIZONTAL);
progressbar.setMinimum(0);
progressbar.setMaximum(100);
progressbar.setValue(0);
progressbar.setStringPainted(true);
progressbar.setPreferredSize(new Dimension(300,20));
progressbar.setBorderPainted(true);
progressbar.setBackground(Color.pink);
  
thread = new MyThread();
JPanel panel=new JPanel();
b=new JButton("安装");
b.setForeground(Color.blue);
b.addActionListener(this);
panel.add(b);contentPanel.add(panel,BorderLayout.NORTH);
contentPanel.add(progressbar,BorderLayout.CENTER);
contentPanel.add(label,BorderLayout.SOUTH);
  
frame.setVisible(true);
}
public void actionPerformed(ActionEvent e)
{
if(e.getSource()==b)
{
thread.start();
value += len/(float)size*100;
System.out.println("...."+value);
}}
//线程类
public class MyThread extends Thread
{
public MyThread()
{
}public void run()
{
while(doing)
{
progressbar.setValue(value);
}
}
}
public static void main(String[] args)  
{
ProgressBar app=new ProgressBar();
}
}