eclipse 如何将 ActionListener 添加到 JMenuItem？
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How to add ActionListener to JMenuItem?
提问by Mina Hafzalla
I'm trying to add ActionListener to JMenuItem in my java menu.
我正在尝试将 ActionListener 添加到我的 Java 菜单中的 JMenuItem。
Here is a screenshot of the menu:
这是菜单的屏幕截图：
I want to add ActionListener to "Rectangle" JMenuItem in order to show up the rectangle shape upon clicking on the "Rectangle" menu item. I tried many times to add the ActionListener but I fail every time.
我想将 ActionListener 添加到“矩形”JMenuItem，以便在单击“矩形”菜单项时显示矩形形状。我尝试了很多次添加 ActionListener 但每次都失败了。
Here is my code:
这是我的代码：
Class "menubar.java" :
类“menubar.java”：
import javax.swing.*;
public class menubar extends JFrame{
public menubar(){
JMenuBar menubar = new JMenuBar();
setJMenuBar(menubar);
JMenu shape = new JMenu("Shape");
menubar.add(shape);
JMenuItem rect = new JMenuItem("Rectangle");
shape.add(rect);
JMenuItem star = new JMenuItem("Star");
shape.add(star);
JMenu color = new JMenu("Color");
menubar.add(color);
JMenuItem black = new JMenuItem("Black");
color.add(black);
JMenuItem orange = new JMenuItem("Orange");
color.add(orange);
}
public static void main(String[] args) {
menubar gui = new menubar();
gui.setTitle("Menu Bar");
gui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
shapes SPS = new shapes();
gui.add(SPS);
gui.setSize(500,300);
gui.setVisible(true);
gui.setLocationRelativeTo(null);
}
}
Class "shapes.java" :
类“shapes.java”：
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class shapes extends JPanel{
int midX = 220;
int midY = 90;
int radius[] = {60,20,50,20};
int nPoints = 16;
int[] X = new int[nPoints];
int[] Y = new int[nPoints];
public void paintComponent(Graphics gphcs){
super.paintComponent(gphcs);
this.setBackground(Color.WHITE);
gphcs.setColor(Color.BLUE);
gphcs.fillRect(20,35,100,30);
gphcs.setColor(Color.RED);
gphcs.drawString("Welcome to Java", 20, 20);
for (int i=0; i < nPoints; i++) {
double x = Math.cos(i * ((2 * Math.PI) / nPoints)) * radius[i % 4];
double y = Math.sin(i * ((2 * Math.PI) / nPoints)) * radius[i % 4];
X[i] = (int) x + midX;
Y[i] = (int) y + midY;
}
gphcs.setColor(Color.GREEN);
gphcs.fillPolygon(X, Y, nPoints);
}
}
I would be very thankful if anybody helped me with this issue.
如果有人帮助我解决这个问题，我将非常感激。
Thanks for your time..
谢谢你的时间..
采纳答案by sparkyShorts
One way that you can add an ActionListener to your container is :
您可以向容器添加 ActionListener 的一种方法是：
public class JMenuClass extends JFrame implements ActionListener
公共类 JMenuClass 扩展 JFrame 实现 ActionListener
Then, for each JMenuItem that you need a listener, you would do
然后，对于每个需要侦听器的 JMenuItem，你会做
item.addActionListener(this)
item.addActionListener(this)
At the bottom of your class, you would need to add your actionPerformed methods, or however you want to implement it.
在类的底部，您需要添加 actionPerformed 方法，或者您想要实现它。
Cheers
干杯
