我正在尝试在单击时动态构建一个 JMenu
(我只得到一个空菜单),下面是我的代码。
final JMenu JMWindows = new JMenu("Opened Windows");
JMWindows.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
for(JInternalFrame ji : desktop.getAllFrames())
{
JMWindows.add(ji.getTitle());
}
}
});
我意识到 actionperformed
从未被调用,JMenu
在 JMenuBar
中。可能是什么问题?
最佳答案
您将
ActionListener
添加到JMenu
这不能为JMenu
使用MenuListener
并通过JMenu#addMenuListener(..)
进行设置您还需要在
JMenu
实例上添加/删除组件后调用revalidate()
和repaint()
或者更改不会反射(reflect)出来(我们也可以在容器实例上调用它,即JMenuBar
或JFrame
,但我们知道只有 1 个特定的JMenu
会更改,因此不需要 IMO)。请注意您的变量命名方案
JMWindow
应该是jmWindow
/jMWindow
变量始终以无大写字母和第一个字母开头此后的每个新词都会大写(常量和枚举
除外)。
这是一个使用 MenuListener
的例子:
import java.awt.*;
import java.awt.event.*;
import javax.swing.JDesktopPane;
import javax.swing.JFrame;
import javax.swing.JInternalFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.SwingUtilities;
import javax.swing.event.MenuEvent;
import javax.swing.event.MenuListener;
public class Test {
private JDesktopPane jdpDesktop;
private static int openFrameCount = 0;
final JFrame frame = new JFrame("JInternalFrame Usage Demo");
public Test() {
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// A specialized layered pane to be used with JInternalFrames
jdpDesktop = new JDesktopPane() {
@Override
public Dimension getPreferredSize() {
return new Dimension(500, 500);
}
};
for (int i = 0; i < 3; i++) {
createFrame(); // Create first window
}
frame.setContentPane(jdpDesktop);
frame.setJMenuBar(createMenuBar());
// Make dragging faster by setting drag mode to Outline
jdpDesktop.putClientProperty("JDesktopPane.dragMode", "outline");
frame.pack();
frame.setVisible(true);
}
protected JMenuBar createMenuBar() {
JMenuBar menuBar = new JMenuBar();
JMenu menu = new JMenu("Frame");
menu.setMnemonic(KeyEvent.VK_N);
JMenuItem menuItem = new JMenuItem("New IFrame");
menuItem.setMnemonic(KeyEvent.VK_N);
menuItem.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
createFrame();
}
});
menu.add(menuItem);
menuBar.add(menu);
final JMenu jmWindows = new JMenu("Opened Windows");
jmWindows.addMenuListener(new MenuListener() {
@Override
public void menuSelected(MenuEvent me) {
jmWindows.removeAll();//remove previous opened window jmenuitems
for (JInternalFrame ji : jdpDesktop.getAllFrames()) {
JMenuItem menuItem = new JMenuItem(ji.getTitle());
jmWindows.add(menuItem);
}
jmWindows.revalidate();
jmWindows.repaint();
jmWindows.doClick();
}
@Override
public void menuDeselected(MenuEvent me) {
}
@Override
public void menuCanceled(MenuEvent me) {
}
});
menuBar.add(jmWindows);
return menuBar;
}
protected void createFrame() {
Test.MyInternalFrame frame = new Test.MyInternalFrame();
frame.setVisible(true);
// Every JInternalFrame must be added to content pane using JDesktopPane
jdpDesktop.add(frame);
try {
frame.setSelected(true);
} catch (java.beans.PropertyVetoException e) {
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
new Test();
}
});
}
class MyInternalFrame extends JInternalFrame {
static final int xPosition = 30, yPosition = 30;
public MyInternalFrame() {
super("IFrame #" + (++openFrameCount), true, // resizable
true, // closable
true, // maximizable
true);// iconifiable
setSize(300, 300);
// Set the window's location.
setLocation(xPosition * openFrameCount, yPosition
* openFrameCount);
}
}
}
关于java - 如何动态构建 JMenu?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/13821504/