我制作了jbutton并添加了ActionListner，但public void actionPerformed（ActionEvent e）{}中的代码执行了两次。它打印测试两次，而不是一次。这是我的代码
JButton testbut=new JButton("Test");
ListenForButton2 l=new ListenForButton2();
testbut.addActionListener(l);
private class ListenForButton2 implements ActionListener{
@Override
public void actionPerformed(ActionEvent e) {
if(e.getSource() == testbut){System.out.println("tEST");}
}
}
这是完整的代码，如果这还不行。看起来像问题就是在我的按钮上添加两个动作监听器。“if（testbut.getActionListeners（）。length＆lt; 1））testbut.addActionListener（l）;”fixed但是你可以找到我在哪里添加两个动作监听器来测试按钮
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.Shape;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.Arc2D;
import java.awt.geom.CubicCurve2D;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Line2D;
import java.awt.geom.QuadCurve2D;
import java.awt.geom.Rectangle2D;
import java.awt.geom.RoundRectangle2D;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class Game extends JFrame {
JButton but1 = new JButton("MakeMoney");
JButton button1 = new JButton("Current money");
JButton testbut=new JButton("Make money");
int money = 0;
double currentMoney;
String moneyString = "";
String box1txt="Text for box one";
String[] boxtext={"Newspaper Delivery","Car wash","Pizza Delivery","Donut shop","Shrimp boat","Hockey team","Movie Studio","Bank","Oil Company"};
String[] prices={"60.00","720.00","8,640.00","103,680.00","1,244,160.00","14,929,920.00","179,159,040.00","2.149 billion","25.798 billion"};
public static void main(String[] args) {
new Game();
}
public Game() {
try {
this.setContentPane(new JLabel(new ImageIcon(ImageIO.read(new File("C:/Users/TPC/workspace/ProjectMoney/Resources/backgroundForApp.png")))));
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
this.setLayout(new BorderLayout());
button1.setContentAreaFilled(false);
ListenForButton lforButton = new ListenForButton();
but1.addActionListener(lforButton);
JPanel thePanel = new JPanel();
thePanel.add(button1);
thePanel.add(but1);
//thePanel.add(testbut);
this.setSize(1042, 617);
this.setLocationRelativeTo(null);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setTitle("Project Money");
this.add(thePanel, BorderLayout.NORTH);
this.add(new DrawStuff(), BorderLayout.CENTER);
this.setResizable(true);
this.setVisible(true);
Sound sound1 = new Sound();
String sound = "file:C:/Users/TPC/Downloads/sound.wav";
sound1.playMusic(sound);
}
private class ListenForButton implements ActionListener {
public void actionPerformed(ActionEvent e) {
if (e.getSource() == but1) {
money += 10;
moneyString = Integer.toString(money);
button1.setText("$" + moneyString);
}
}
}
private class ListenForButton2 implements ActionListener{
@Override
public void actionPerformed(ActionEvent e) {
if(e.getSource() == testbut){System.out.println("tEST");}
}
}
private class DrawStuff extends JComponent {
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D graph2 = (Graphics2D) g;
graph2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
Shape drawRoundRec = new RoundRectangle2D.Double(170,40,250,66,45, 45);
//first num xpos,secound num ypost,third num sirina,fourht num duzina
int x1=170; int y1=40; int x2=250; int y2=66; int def=45;
Shape drawRoundRec2=new RoundRectangle2D.Double(x1,(y1+80),x2,y2,def,def);
Shape drawRoundRec3=new RoundRectangle2D.Double(x1,(y1+80+80),x2,y2,def,def);
Shape drawRoundRec4=new RoundRectangle2D.Double(x1,(y1+80+80+80),x2,y2,def,def);
Shape drawRoundRec5=new RoundRectangle2D.Double(x1,(y1+80+80+80+80),x2,y2,def,def);
Shape drawRoundRect6=new RoundRectangle2D.Double(x1+330,40,250,66,def, def);
Shape drawRoundRect7=new RoundRectangle2D.Double(x1+330,(y1+80),250,66,def, def);
Shape drawRoundRect8=new RoundRectangle2D.Double(x1+330,(y1+80+80),250,66,def, def);
Shape drawRoundRect9=new RoundRectangle2D.Double(x1+330,(y1+80+80+80),250,66,def, def);
Shape drawRoundRect10=new RoundRectangle2D.Double(x1+330,(y1+80+80+80+80),250,66,def, def);
graph2.setPaint(Color.BLACK);
graph2.setColor(Color.LIGHT_GRAY);
graph2.fill(drawRoundRec); graph2.fill(drawRoundRec2);
graph2.fill(drawRoundRec3); graph2.fill(drawRoundRec4); graph2.fill(drawRoundRec5); graph2.fill(drawRoundRect6);
graph2.fill(drawRoundRect7); graph2.fill(drawRoundRect8); graph2.fill(drawRoundRect9); graph2.fill(drawRoundRect10);
graph2.setPaint(Color.BLACK);
graph2.draw(drawRoundRec2); graph2.draw(drawRoundRec3); graph2.draw(drawRoundRec4);
graph2.draw(drawRoundRec5); graph2.draw(drawRoundRect6); graph2.draw(drawRoundRect7); graph2.draw(drawRoundRect8);
graph2.draw(drawRoundRect9); graph2.draw(drawRoundRect10);
Font font=new Font("Serif",Font.PLAIN,30);
g.setFont(font); g.drawString(box1txt,190,80); g.drawString(boxtext[0],190,150); g.drawString(boxtext[1],190,150+80); g.drawString(boxtext[2],190,150+90+70);
g.drawString(boxtext[3],190,150+90+70+80);
g.drawString(boxtext[4],520,80); g.drawString(boxtext[5],520,150); g.drawString(boxtext[6],520,150+80); g.drawString(boxtext[7],520,150+90+70);
g.drawString(boxtext[8],520,150+90+70+80);
g.drawString(prices[0],190,150+30); g.drawString(prices[1],190,150+80+30); g.drawString(prices[2],190,150+90+70+30);
g.drawString(prices[3],190,150+90+70+80+30);
g.drawString(prices[4],520,80+25); g.drawString(prices[5],520,150+30); g.drawString(prices[6],520,150+80+30); g.drawString(prices[7],520,150+90+70+30);
g.drawString(prices[8],520,150+90+70+80+30);
testbut.setLocation(180,70);
Dimension d = new Dimension(100,40);
testbut.setSize(d);
ListenForButton2 l=new ListenForButton2();
if (testbut.getActionListeners().length<1) testbut.addActionListener(l);
this.add(testbut);
}
}
}
答案 0 :(得分：3)
确保只添加一次动作侦听器。
您可以通过testbut.getActionListeners().length获取听众数。
在DrawStuff类的paintComponent中，它扩展了JComponent，你只需要添加一次监听器。与第一个听众相同。
不同之处在于，第一个是在构造函数中添加的。而JComponent的paintComponent方法可以被称为倍数倍。
关于如何以及何时调用它，this answer可能会对您有所帮助。