如何爲此附加定時器？

Question

我想附加一個2秒（2000毫秒）計時器到這個燈光，以便它自動前進到下一個顏色。我一直在閱讀Java文檔，我不明白如何使用它。

import java.awt.event.*; 
import javax.swing.*; 
import java.awt.*; 



public class Lab4Frame extends JFrame { 

    Lab4Frame(){ 
     this.setLayout(new BorderLayout()); 
     setTitle("Lab 4 - Application #1"); 
     Lab4Panel p = new Lab4Panel(); 
     Lab4RadioButtonPanel p2 = new Lab4RadioButtonPanel(p); 

     add(p, BorderLayout.CENTER); 
     add(p2, BorderLayout.SOUTH); 
    } 

    public static void main(String[] args){ 

      Lab4Frame frame = new Lab4Frame(); 
      frame.setTitle("Lab4 Application # 1"); 
      frame.setLocationRelativeTo(null); 
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
      frame.setSize(600, 600); 
      frame.setVisible(true); 
    } 

} 

class Lab4RadioButtonPanel extends JPanel { 
    Lab4Panel canvas; 
    //Lab4RadioButtonPanel canvas2 = new Lab4RadioButtonPanel(); 

    public Lab4RadioButtonPanel(Lab4Panel canvas) { 
    this.canvas = canvas; 
     boolean red, green, yellow; 
     this.setLayout(new FlowLayout()); 
     JRadioButton jrbRed = new JRadioButton("Red", true); 
     JRadioButton jrbYellow = new JRadioButton("Yellow"); 
     JRadioButton jrbGreen = new JRadioButton("Green"); 

     this.setBorder(BorderFactory.createLineBorder(Color.black)); 

     ButtonGroup group = new ButtonGroup(); 
     group.add(jrbRed); 
     group.add(jrbYellow); 
     group.add(jrbGreen); 


     this.add(jrbRed); 
     this.add(jrbYellow); 
     this.add(jrbGreen); 

     jrbRed.addActionListener(new RedListener(canvas)); 
     jrbYellow.addActionListener(new YellowListener(canvas)); 
     jrbGreen.addActionListener(new GreenListener(canvas)); 

    } 
} 


class Lab4Panel extends JPanel{ 


    public Lab4Panel(){} 



    boolean red = true; 
    boolean green = false; 
    boolean yellow = false; 
    int radius = 5; 
    int x = -1; 
    int y = -1; 

    public void setRed(){ 
     yellow = false; 
     green = false; 
     red = true; 
    } 

    public void setYellow(){ 
     red = false; 
     green = false; 
     yellow = true; 
    } 

    public void setGreen(){ 
     red = false; 
     yellow = false; 
     green = true; 
    } 

    protected void paintComponent(Graphics g){ 
     if (x<0 || y<0) { 
      x = getWidth()/2 - radius; 
      y = getHeight()/2 - radius; 
     } 
     super.paintComponent(g); 
     g.drawRect(x - 10,y - 90, 40, 120); 
     g.drawRect(x - 5,y - 90, 40, 120); 
     g.setColor(Color.RED); 
     g.drawOval(x,y - 80, 4 * radius, 4 * radius); 
     g.setColor(Color.YELLOW); 
     g.drawOval(x,y - 40, 4 * radius, 4 * radius); 
     g.setColor(Color.GREEN); 
     g.drawOval(x,y, 4 * radius, 4 * radius); 


     if(red){ 
      g.setColor(Color.RED); 
      g.fillOval(x,y - 80, 4 * radius, 4 * radius); 
      repaint(); 
     } 

     else if (yellow){ 
      g.setColor(Color.YELLOW); 
      g.fillOval(x,y - 40, 4 * radius, 4 * radius); 
      repaint(); 
     } 

     if(green){ 
      g.setColor(Color.GREEN); 
      g.fillOval(x,y, 4 * radius, 4 * radius); 
      repaint(); 
     } 

    } 


} 


class RedListener implements ActionListener{ 
    private Lab4Panel canvas; 

    RedListener(Lab4Panel canvas) { 
    this.canvas = canvas; 
    } 

    public void actionPerformed(ActionEvent e){ 
     canvas.setRed(); 
    } 
} 

class YellowListener implements ActionListener{ 
    private Lab4Panel canvas; 

    YellowListener(Lab4Panel canvas) { 
    this.canvas = canvas; 
    } 

    public void actionPerformed(ActionEvent e){ 
     canvas.setYellow(); 
    } 
} 

class GreenListener implements ActionListener{ 
    //private Lab4RadioButtonPanel canvas; 
    private Lab4Panel canvas; 

    GreenListener(Lab4Panel canvas) { 
    this.canvas = canvas; 
    } 

    public void actionPerformed(ActionEvent e){ 
     canvas.setGreen(); 
    } 
} 

Answer 1

class Lab4Panel extends JPanel{ 

public Lab4Panel(){ 

Timer timer = new Timer(2000, new TimerListener()); 
timer.start(); 

}