对按钮使用动作监听器

Question

代码：Java Sphere类

 import javax.swing.*;
 import java.awt.*;
 import java.awt.geom.Ellipse2D;
public class Sphere extends JPanel {
private boolean flashinglights = false;
private int x = 168;
private int y = 75;

public void paintComponent(Graphics g) { 
    super.paintComponent(g);
    Graphics2D g2 = (Graphics2D) g;
    if (flashinglights) { //This is the flash option. Here it should change between grey and orange
        g2.setColor(Color.ORANGE);
        Ellipse2D.Double ball = new Ellipse2D.Double(x, y, 50, 50);
        g2.draw(ball);
        g2.fill(ball);
    } else {
        g2.setColor(Color.gray); //This should stay grey as it does now.
        Ellipse2D.Double ball = new Ellipse2D.Double(x, y, 50, 50);
        g2.draw(ball);
        g2.fill(ball);
    }
}
public void chooseflashinglights(){ //Ignore these methods
    flashinglights = false;
}
public void choosesteady(){
    flashinglights = true;
}
public void flickerorange(int d) { y = y + d; }

public void flickergrey(int d) { y = y + d; }

public static void main(String[] args) {
    JFrame scFrame = new AnimationViewer();
    scFrame.setTitle("Circle");
    scFrame.setSize(400, 400);
    scFrame.setDefaultCloseOperation((JFrame.EXIT_ON_CLOSE));
    scFrame.setVisible(true);
}

}

动画查看器类：

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

public class AnimationViewer extends JFrame {
JButton jbtFlash = new JButton("Flash");
JButton jbtSteady = new JButton("Steady");
JPanel bPanel = new JPanel();
Sphere sphPanel = new Sphere();
Timer timer;
public AnimationViewer() {
    this.add(bPanel, BorderLayout.SOUTH);
    bPanel.add(jbtFlash);
    bPanel.setLayout(new GridLayout(1,2));
    bPanel.add(jbtSteady);
    this.add(sphPanel, BorderLayout.CENTER);

    jbtSteady.addActionListener(new SteadyLights());
    jbtFlash.addActionListener(new FlashingLights());
    timer = new Timer(100, new TimerListener());
    timer.start();
}

class TimerListener implements ActionListener {
    public void actionPerformed(ActionEvent e) {
        sphPanel.flickerorange(0);
        sphPanel.flickergrey(0);
        repaint();
    }
}
class FlashingLights implements ActionListener{
    public void actionPerformed(ActionEvent e){
        sphPanel.chooseflashinglights();
    }
}
class SteadyLights implements ActionListener{
    public void actionPerformed(ActionEvent e){
        sphPanel.choosesteady();
    }
}
}

现在屏幕上出现了一个球体。下面显示了两个按钮。闪光和稳定。在稳定按钮上，它必须保持一种颜色（橙色），而不是。

现在在Flash上，它必须每100毫秒从橙色变为灰色。

我知道这与Action听众有关，但我到底该如何实现呢？

Answer 1

您有很多额外的代码。我会这样做的。在paintComponent方法中写入闪烁逻辑。然后只创建一个计时器。勾选时，每隔100毫秒调用paintComponent方法。在闪烁按钮上单击启动计时器，在稳定按钮上单击停止计时器并调用paintComponent一次。

球体类别：

public class Sphere extends JPanel {
private boolean flashinglights = false;
private int x = 168;
private int y = 75;
private Color[] colors = new Color[] {Color.ORANGE, Color.GRAY };
private int colorIndex = 0;
public void paintComponent(Graphics g) {
   super.paintComponent(g);
   Graphics2D g2 = (Graphics2D) g;
   if (!flashinglights) {
       g2.setColor(Color.ORANGE);
       Ellipse2D.Double ball = new Ellipse2D.Double(x, y, 50, 50);
       g2.draw(ball);
       g2.fill(ball);
   } else {
       if(colorIndex > colors.length - 1)
           colorIndex = 0;
       g2.setColor(colors[colorIndex++]);
       Ellipse2D.Double ball = new Ellipse2D.Double(x, y, 50, 50);
       g2.draw(ball);
       g2.fill(ball);
   }
}
public void chooseflashinglights(){ //Ignore these methods
   flashinglights = true;
}
public void choosesteady(){
   flashinglights = false;
}
public static void main(String[] args) {
   JFrame scFrame = new AnimationViewer();
   scFrame.setTitle("Circle");
   scFrame.setSize(400, 400);
   scFrame.setDefaultCloseOperation((JFrame.EXIT_ON_CLOSE));
   scFrame.setVisible(true);
}
}

AnimationViewer类：

public class AnimationViewer extends JFrame {
JButton jbtFlash = new JButton("Flash");
JButton jbtSteady = new JButton("Steady");
JPanel bPanel = new JPanel();
Sphere sphPanel = new Sphere();
Timer timer;
public AnimationViewer() {
   this.add(bPanel, BorderLayout.SOUTH);
   bPanel.add(jbtFlash);
   bPanel.setLayout(new GridLayout(1,2));
   bPanel.add(jbtSteady);
   this.add(sphPanel, BorderLayout.CENTER);
   timer = new Timer(100, new TimerListener());
   jbtSteady.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) {
            sphPanel.choosesteady();
            timer.stop();
            sphPanel.repaint();
        }
    });
   jbtFlash.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) {
            sphPanel.chooseflashinglights();
            timer.start();
        }
    });
}
class TimerListener implements ActionListener {
   public void actionPerformed(ActionEvent e) {
       sphPanel.repaint();
   }
}
}

Answer 2

我会做一些不同的事情。

• 我会在绘图JPanel类中有一个字段，指示应该显示什么颜色
• 例如，如果只有两种颜色被交换，我会使用一个布尔字段，并在计时器中交换它的值，然后根据它的值绘制颜色
• paintComponent方法将使用该字段（布尔值）来决定g.setColor(...)使用哪种颜色
• 如果绘制了许多颜色，则字段可以是Color数组与数组中的int索引的组合。然后根据需要增加索引，并使用paintComponent中的索引来决定使用哪种颜色绘制
• 我会在Timer的ActionListener中更改该字段——只需一次调用即可更改，而不是奇怪的闪烁橙色和灰色的调用
• 我会用一个按钮启动计时器
• 我会用另一个按钮停止它。这就是按钮的动作监听器所要做的一切，只需启动或停止计时器