写的一个小程序有点错误，求高人指教

Question

本事想写一个用三个按钮控制三个线程画矩形的，可是他们都不工作。
本人刚学java,菜鸟一枚，求各种前辈不吝赐教，在此多谢。//ThreadTest.javaimport java.awt.*;
import javax.swing.*;public class ThreadTest {



public static void main(String[] args)
{
Toolkit tk=Toolkit.getDefaultToolkit();
Dimension screenSize=tk.getScreenSize();
int screenWidth=screenSize.width;
int screenHeight=screenSize.height;

ThreadFrame threadFrame=new ThreadFrame();
threadFrame.setLocation(screenWidth/3, screenHeight/5);

    threadFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    threadFrame.setVisible(true);
}
}
//ThreadFrame,javaimport java.awt.*;
import java.awt.event.*;
import javax.swing.*;class ThreadFrame extends JFrame 
{
DrawThread draw=new DrawThread(50,50,20,10);
Container contentPane=getContentPane();
JPanel panel1=new JPanel();
JPanel panel2=new JPanel();

JButton button1=new JButton("线程1开始");
JButton button2=new JButton("线程2开始");
JButton button3=new JButton("线程3开始");

public ThreadFrame()
{
setTitle("线程并发执行演示");
setSize(480,480);

panel2.add(button1);
panel2.add(button2);
panel2.add(button3);

repaint();

button1.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
if(draw.start==0)
{
DrawThread draw1=new DrawThread(50,50,20,5);
draw1.start();
draw.start=1;
button1.setText("线程1暂停");
}
else if(draw.start==1)
{
draw.change();
button1.setText("线程1开始");
}
else
{
draw.change();
button1.setText("线程1暂停");
}

}
});

button2.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
if(draw.start==0)
{
DrawThread draw2=new DrawThread(50,50,20,5);
draw2.start();
draw.start=1;
button2.setText("线程2暂停");
}
else if(draw.start==1)
{
draw.change();
button2.setText("线程2开始");
}
else
{
draw.change();
button2.setText("线程2暂停");
}
}
});

button3.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
if(draw.start==0)
{
DrawThread draw3=new DrawThread(50,50,20,5);
draw3.start();
draw.start=1;
button3.setText("线程3暂停");
}
else if(draw.start==1)
{
draw.change();
button3.setText("线程3开始");
}
else
{
draw.change();
button3.setText("线程3暂停");
}
}
});

contentPane.add(panel1,BorderLayout.NORTH);
contentPane.add(panel2,BorderLayout.SOUTH);
}

public void paintComponent(Graphics g)
{
super.paintComponents(g);

g.drawString("线程1", 10, 50);
g.drawString("线程2", 10, 100);
g.drawString("线程3", 10, 150);
}

class DrawThread extends Thread
{
int x, y,WIDTH,HEIGHT;
int start;
int speed;
DrawThread(int x, int y, int HEIGHT,int speed) 
{
this.x = x;
this.y = y;
this.HEIGHT = HEIGHT;   //矩形的高
this.speed = speed;
this.start = 0;
} public void drawMe()
        {
Graphics g = panel1.getGraphics();     //把画笔给panel1
g.setColor(Color.red);
g.fillRect(x, y,WIDTH,HEIGHT );        //panel1自己在画矩形
} public void change()     //改变标志
{
this.start *= -1;
} public void run() 
{ while (true)    //循环执行
{
this.drawMe();    //panel1画矩形
if (start == 1)
{
if (WIDTH > 400) 
{
Graphics g = panel1.getGraphics();
Color c = g.getColor();
g.setColor(Color.white);
g.fillRect(x, y,WIDTH,HEIGHT );
g.setColor(c);
WIDTH = 0;
}
WIDTH += speed;

}
try 
{
Thread.sleep(100);
} 
catch (Exception e) {}
}
} }

}

Answer 1

我swing也不是很好，大概帮你看了下，问题有几点
首先，
contentPane.add(panel1, BorderLayout.NORTH);
这个panel1就在界面上面，很小的一块
你可以用panel1.setBackground(Color.red);看看具体是什么样子的
你的它的画笔来画，我不知道会有什么问题第二，
DrawThread这个的WIDTH一直是0，你自己调试看看我改了两句contentPane.add(panel1, BorderLayout.CENTER);drawMe()里面加了WIDTH=30;
现在能够看到一块红的，因为具体不知道你要干什么，
你可以照着改了再调看看

Answer 2

关键还是在start的控制上，我想用三个线程演示同时画矩形，单个或两个一起画矩形，由于cpu分配资源的问题，我想实现的就是一个线程工作是画的非常快，因为现在只有他一个占用cpu,三个一起画就速度就满了，我知道每个线程停止时要让他释放自己的锁，好像要用到wait(),notify()。
有木有人能帮我实现下。代码我改了一下，可以运行了，但是不能体现cpu的时间转轮调度算法，要让停止的线程释放它所占的资源。import java.awt.*;
import javax.swing.*;public class ThreadTest {



public static void main(String[] args)
{
Toolkit tk=Toolkit.getDefaultToolkit();
Dimension screenSize=tk.getScreenSize();
int screenWidth=screenSize.width;
int screenHeight=screenSize.height;

ThreadFrame threadFrame=new ThreadFrame();
threadFrame.setLocation(screenWidth/3, screenHeight/5);

    threadFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    threadFrame.setVisible(true);
}
}
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;class ThreadFrame extends JFrame 
{
DrawThread draw=new DrawThread(50,50,20,10);
Container contentPane=getContentPane();
JPanel panel1=new JPanel();
JPanel panel2=new JPanel();

JButton button1=new JButton("线程1开始");
JButton button2=new JButton("线程2开始");
JButton button3=new JButton("线程3开始");

public ThreadFrame()
{
setTitle("线程并发执行演示");
setSize(480,480);

panel2.add(button1);
panel2.add(button2);
panel2.add(button3);

repaint();

button1.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
DrawThread draw1=new DrawThread(50,50,20,5);
draw1.start();
button1.setText("线程1暂停");

}
});

button2.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
DrawThread draw2=new DrawThread(50,150,20,5);
draw2.start();
button2.setText("线程2暂停");
}
});

button3.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{

DrawThread draw3=new DrawThread(50,250,20,5);
draw3.start();
button3.setText("线程3暂停");
}
});

contentPane.add(panel1,BorderLayout.CENTER );
contentPane.add(panel2,BorderLayout.SOUTH);
}

public void paintComponent(Graphics g)
{
super.paintComponents(g);

g.drawString("线程1", 10, 50);
g.drawString("线程2", 10, 100);
g.drawString("线程3", 10, 150);
}

class DrawThread extends Thread
{
int x, y,WIDTH=0,HEIGHT;
int start;
int speed;
DrawThread(int x, int y, int HEIGHT,int speed) 
{
this.x = x;
this.y = y;
this.HEIGHT = HEIGHT;   //矩形的高
this.speed = speed;
this.start = 1;
} public void drawMe()
        {
Graphics g = panel1.getGraphics();     //把画笔给panel1
g.setColor(Color.red);
g.fillRect(x, y,WIDTH,HEIGHT );        //panel1自己在画矩形
} public void change()     //改变标志
{
this.start *= -1;
} public void run() 
{
while (true)          //循环执行
{
this.drawMe();    //panel1画矩形
if (start == 1)
{
if (WIDTH > 400) 
{
Graphics g = panel1.getGraphics();
Color c = g.getColor();
g.setColor(Color.white);
g.fillRect(x, y,WIDTH,HEIGHT );
g.setColor(c);
WIDTH = 0;
}
WIDTH += speed;


}
try 
{
Thread.sleep(100);
} 
catch (Exception e) {}
}
} }

}

Answer 3

按你说的改了下，也许是这个样子？
我之改了第一个按钮class ThreadFrame extends JFrame {
DrawThread draw = new DrawThread(50, 50, 20, 10);
Container contentPane = getContentPane();
JPanel panel1 = new JPanel();
JPanel panel2 = new JPanel(); JButton button1 = new JButton("线程1开始");
JButton button2 = new JButton("线程2开始");
JButton button3 = new JButton("线程3开始"); DrawThread draw1;
DrawThread draw2 = new DrawThread(50, 150, 20, 5);
DrawThread draw3 = new DrawThread(50, 250, 20, 5);

public ThreadFrame() {
setTitle("线程并发执行演示");
setSize(480, 480); panel2.add(button1);
panel2.add(button2);
panel2.add(button3); repaint(); button1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if(draw1 == null){
draw1 = new DrawThread(50, 50, 20, 5);
draw1.start = 1;
draw1.start();
}else{
draw1.change();
if(draw1.start == -1)
try {
draw1.suspend();
} catch (Exception e1) {
e1.printStackTrace();
}
else
draw1.resume();
}
button1.setText("线程1暂停");
}
}); button2.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {

draw2.start();
button2.setText("线程2暂停");
}
}); button3.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
draw3.start();
button3.setText("线程3暂停");
}
}); contentPane.add(panel1, BorderLayout.CENTER);
contentPane.add(panel2, BorderLayout.SOUTH);
} public void paintComponent(Graphics g) {
super.paintComponents(g); g.drawString("线程1", 10, 50);
g.drawString("线程2", 10, 100);
g.drawString("线程3", 10, 150);
} class DrawThread extends Thread {
int x, y, WIDTH = 0, HEIGHT;
int start = -1;
int speed; DrawThread(int x, int y, int HEIGHT, int speed) {
this.x = x;
this.y = y;
this.HEIGHT = HEIGHT; // 矩形的高
this.speed = speed;
} public void drawMe() {
Graphics g = panel1.getGraphics(); // 把画笔给panel1
g.setColor(Color.red);
g.fillRect(x, y, WIDTH, HEIGHT); // panel1自己在画矩形
} public void change() // 改变标志
{
this.start *= -1;
} public void run() {
while (true) // 循环执行
{
this.drawMe(); // panel1画矩形
if (start == 1) {
if (WIDTH > 400) {
Graphics g = panel1.getGraphics();
Color c = g.getColor();
g.setColor(Color.white);
g.fillRect(x, y, WIDTH, HEIGHT);
g.setColor(c);
WIDTH = 0;
}
WIDTH += speed; }
try {
Thread.sleep(100);
} catch (Exception e) {
}
}
} }}

Answer 4

我改了下，但是还是不能让暂停的线程把他的cpu资源让出来，就是每个线程画矩形的速度不受其他两个线程的影响，查了一下，说要用wait和notify，但是要和synchronized一起用，我不是太懂，能不能帮我改下，还有按钮的名称我怎么改不了。import java.awt.*;
import java.awt.event.*;
import javax.swing.*;class ThreadFrame extends JFrame {
    Container contentPane = getContentPane();
    JPanel panel1 = new JPanel();
    JPanel panel2 = new JPanel();
 
    JButton button1 = new JButton("线程1开始");
    JButton button2 = new JButton("线程2开始");
    JButton button3 = new JButton("线程3开始");
 
    DrawThread draw1,draw2,draw3;  
     
    public ThreadFrame() {
        setTitle("线程并发执行演示");
        setSize(480, 480);
 
        panel2.add(button1);
        panel2.add(button2);
        panel2.add(button3);
 
        button1.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                if(draw1 == null){
                    draw1 = new DrawThread(50, 50, 20, 3);
                    draw1.start = 1;
                    draw1.start();
                }else{
                    draw1.change();
                    if(draw1.start == -1)
                        try {
                            draw1.wait();
                            button1.setText("线程1开始");
                        } 
                        catch (Exception e1) {
                            e1.printStackTrace();
                        }
                    else
                    {
                        draw1.notify();
                        button1.setText("线程1暂停");
                    }
                }
            }
        });
 
        button2.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
             if(draw2 == null){
             draw2 = new DrawThread(50, 75, 20, 3);
             draw2.start = 1;
             draw2.start();
                }else{
                 draw2.change();
                    if(draw2.start == -1)
                        try {
                         draw2.wait();
                         button1.setText("线程2开始");
                        } 
                        catch (Exception e1) {
                            e1.printStackTrace();
                        }
                    else
                    {
                     draw2.notify();
                     button1.setText("线程2暂停");
                    }
                }
            }
        });
 
        button3.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
 
             if(draw3 == null){
             draw3 = new DrawThread(50, 100, 20, 3);
             draw3.start = 1;
             draw3.start();
                }else{
                 draw3.change();
                    if(draw3.start == -1)
                        try {
                         draw3.wait();
                         button1.setText("线程3开始");
                        } 
                        catch (Exception e1) {
                            e1.printStackTrace();
                        }
                    else
                    {
                     draw3.notify();
                     button1.setText("线程3暂停");
                    }
                }
            }
        });
 
        contentPane.add(panel1, BorderLayout.CENTER);
        contentPane.add(panel2, BorderLayout.SOUTH);
        
    }
 
 
    class DrawThread extends Thread 
    {
        int x, y, WIDTH = 0, HEIGHT;
        int start = -1;
        int speed;
 
        DrawThread(int x, int y, int HEIGHT, int speed)
        {
            this.x = x;
            this.y = y;
            this.HEIGHT = HEIGHT; // 矩形的高
            this.speed = speed;
        }
 
        public void drawMe() 
        {
            Graphics g = panel1.getGraphics(); // 把画笔给panel1
            g.setColor(Color.red);
            g.fillRect(x, y, WIDTH, HEIGHT); // panel1自己在画矩形
        }
 
        public void change() // 改变标志
        {
            this.start *= -1;
        }
 
        public synchronized void run() 
        {
            while (true) // 循环执行
            {
                this.drawMe(); // panel1画矩形
                if (start == 1)
                {
                    if (WIDTH > 400)
                    {
                        Graphics g = panel1.getGraphics();
                        Color c = g.getColor();
                        g.setColor(Color.white);
                        g.fillRect(x, y, WIDTH, HEIGHT);
                        g.setColor(c);
                        WIDTH = 0;
                    }
                    WIDTH += speed;
 
                }
                try {
                    Thread.sleep(80);
                } catch (Exception e) {}
            }
        }
    }
    
    public static void main(String[] args)
    {
     Toolkit tk=Toolkit.getDefaultToolkit();
Dimension screenSize=tk.getScreenSize();
int screenWidth=screenSize.width;
int screenHeight=screenSize.height;

ThreadFrame threadFrame=new ThreadFrame();
threadFrame.setLocation(screenWidth/3, screenHeight/5);

    threadFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    threadFrame.setVisible(true);
    }
 
}