Java 3个按钮无法触发3个绘图图像
我正在尝试创建一个带有边框布局、3个jbuttons和paint的drawImage组件的项目,以创建一个能够监听按钮按下和更改图像的红绿灯。我知道我的条件语句中的drawImages可以工作,因为如果我取出if语句,图像看起来很好;我知道动作侦听器可以工作,因为我使用一个joptionpane对话框测试了每一个。然而,在目前的形式下,按下按钮时什么也没有发生,我不知道为什么。任何帮助都将不胜感激,我正在学习Java 3个按钮无法触发3个绘图图像,java,swing,if-statement,jbutton,paint,Java,Swing,If Statement,Jbutton,Paint,我正在尝试创建一个带有边框布局、3个jbuttons和paint的drawImage组件的项目,以创建一个能够监听按钮按下和更改图像的红绿灯。我知道我的条件语句中的drawImages可以工作,因为如果我取出if语句,图像看起来很好;我知道动作侦听器可以工作,因为我使用一个joptionpane对话框测试了每一个。然而,在目前的形式下,按下按钮时什么也没有发生,我不知道为什么。任何帮助都将不胜感激,我正在学习 import java.awt.*; import java.awt.event.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class TrafficLight extends JFrame implements ActionListener
{
//establishes panel, button, and boolean variables
private JPanel pN, pS, pE, pW, pC;
private JButton btnWait, btnGo, btnStop;
private boolean redIlluminated = false , greenIlluminated = false , yellowIlluminated = false;
public static void main(String[] args)
{
TrafficLight frame = new TrafficLight();
frame.setSize(750, 850);
frame.createGUI();
frame.setVisible(true);
}
private void createGUI()
{
setDefaultCloseOperation(EXIT_ON_CLOSE);
Container window = getContentPane();
window.setLayout(new BorderLayout());
//custom colors
Color slate=new Color(49, 58, 58);
Color eggshell=new Color(230, 226, 222);
Color easterPink=new Color(249, 170, 170);
Color salmon=new Color(201, 80, 65);
Color dusk=new Color(187, 185, 184);
Color billiards=new Color(71, 88, 68);
//custom fonts
Font buttonFont = new Font("SansSerif", Font.BOLD, 20);
//sets up north jpanel
pN = new JPanel();
pN.setPreferredSize(new Dimension(680,45));
pN.setBackground(eggshell);
window.add (pN, BorderLayout.NORTH);
//button formatting
//establishes go button, font, color, and click event, then adds it to pN panel
btnGo = new JButton ("GO");
btnGo.setFont(buttonFont);
btnGo.setBackground(dusk);
btnGo.addActionListener(
new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
//trigger condition change here to cause the paint event below
greenIlluminated = true;
}
}
);
pN.add(btnGo);
//establishes wait button, font, color, and click event, then adds it to pN panel
btnWait = new JButton("WAIT");
btnWait.setFont(buttonFont);
btnWait.setBackground(dusk);
btnWait.addActionListener(
new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
//trigger condition change here to cause the paint event below
yellowIlluminated = true;
}
}
);
pN.add(btnWait);
//establishes stop button, font, color, and click event, then adds it to pN panel
btnStop = new JButton("STOP");
btnStop.setFont(buttonFont);
btnStop.setBackground(dusk);
btnStop.addActionListener(
new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
//trigger condition change here to cause the paint event below
redIlluminated = true;
}
}
);
pN.add(btnStop);
//east jpanel for stoplight
pE = new JPanel();
pE.setPreferredSize(new Dimension(272,318));
pE.setBackground(billiards);
window.add (pE, BorderLayout.EAST);
//west jpanel
pW = new JPanel();
pW.setPreferredSize(new Dimension(136,318));
pW.setBackground(billiards);
window.add (pW, BorderLayout.WEST);
//center jpanel for car
pC = new JPanel();
pC.setPreferredSize(new Dimension(272,318));
pC.setBackground(slate);
window.add (pC, BorderLayout.CENTER);
//south jpanel
pS = new JPanel();
pS.setPreferredSize(new Dimension(680, 15));
pS.setBackground(eggshell);
window.add (pS, BorderLayout.SOUTH);
}
public void actionPerformed(ActionEvent click) {
}
public void paint(Graphics g) {
super.paint(g);
//draws stoplight
g.drawImage(new ImageIcon(getClass().getResource("red1.png")).getImage(), 460, 150, this);
g.drawImage(new ImageIcon(getClass().getResource("green1.png")).getImage(), 460, 272, this);
g.drawImage(new ImageIcon(getClass().getResource("yellow1.png")).getImage(), 460, 373, this);
//draws car in center
g.drawImage(new ImageIcon(getClass().getResource("car.png")).getImage(), 150, 600, this);
//sets conditions to show images on button click based on boolean logic changed by buttons
if (redIlluminated)
{
g.drawImage(new ImageIcon(getClass().getResource("red2.png")).getImage(), 460, 150, this);
}
else if (greenIlluminated)
{
g.drawImage(new ImageIcon(getClass().getResource("green2.png")).getImage(), 460, 272, this);
}
else if (yellowIlluminated)
{
g.drawImage(new ImageIcon(getClass().getResource("yellow2.png")).getImage(), 460, 373, this);
}
}
}
不确定是否仍然与您相关,但以防其他人偶然发现这个问题 Swing容器不会一直监听对其图形的更改,因此在进行更改时,需要确保调用
repaint()
,以便再次渲染整个容器
在按钮的ActionListener中添加一个方法调用如下所示:
btnGo.addActionListener( new ActionListener() {
public void actionPerformed(ActionEvent ae) {
//trigger condition change here to cause the paint event below, I turn off the other flags so that the if clause in the paint method knows exactly what to paint
greenIlluminated = true;
redIlluminated = false;
yellowIlluminated = false;
//This is the one method that triggers a call to the paint method you overrode
repaint();
}
});
其他ActionListener也需要做类似的改变
作为旁注,如果要将匿名ActionListener类的对象用于按钮,则不需要实现ActionListener接口