java是什么导致绿灯保持绿色?
对不起,这个愚蠢的问题是我的作业。我应该做一个交通灯,当按下按钮时,它会改变灯的颜色。我让它半工作,我遇到的问题是绿灯在红灯阶段一直亮着。我对所有三个阶段都做了同样的事情,所以我不明白为什么它只有一个阶段有问题。 代码:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class ButtonPanel extends JPanel {
int presses;
int gy=200;
int yy=130;
int ry=60;
int filly=ry;
int empty1=gy;
int empty2=yy;
private JButton push;
private JLabel label;
Color light=Color.RED;
public ButtonPanel () {
presses=0;
push=new JButton("Change Light");
push.addActionListener(new ButtonListener());
add(push);
setBackground(Color.white);
setPreferredSize(new Dimension(300,400));
}
public void paint(Graphics g) {
super.paint(g);
setBackground(Color.WHITE);
g.drawOval(120,gy,50,50);
g.drawOval(120,yy,50,50);
g.drawOval(120,ry,50,50);
g.drawRect(95, 50, 100, 210);
g.setColor(light);
g.fillOval(120, filly, 50, 50);
g.setColor(Color.white);
g.fillOval(120, empty1, 50, 50);
g.fillOval(120, empty2, 50, 50);
}
public class ButtonListener implements ActionListener{
public void actionPerformed(ActionEvent e) {
System.out.println(presses);
presses++;
if(presses>2) {
presses=0;
}
if(presses==0) {
light=Color.red;
filly=ry;
System.out.println("check");
empty1=gy;
System.out.println("check");
empty1=yy;
repaint();
}
if(presses==1) {
light=Color.yellow;
filly=yy;
empty1=ry;
empty2=gy;
repaint();
}
if(presses==2) {
light=Color.green;
filly=gy;
empty1=ry;
empty2=yy;
repaint();
}
}
}
}
如果您想编译它,这里是框架和主要方法部分:
import javax.swing.JFrame;
public class TrafficFrame {
public static void main(String[] args) {
JFrame frame= new JFrame("Traffic Light");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
ButtonPanel panel=new ButtonPanel();
frame.getContentPane().add(panel);
frame.pack();
frame.setVisible(true);
}
}
# 1 楼答案
在我看来,这是个简单的打字错误。在这个if块中,您要设置
empty1
两次,而不是设置empty2