如何在Java中创建带有子菜单的弹出菜单
我想为我的程序添加右键单击菜单。我使用以下代码添加了basit菜单:如何在Java中创建带有子菜单的弹出菜单,java,swing,menu,right-click,jpopupmenu,Java,Swing,Menu,Right Click,Jpopupmenu,我想为我的程序添加右键单击菜单。我使用以下代码添加了basit菜单: Pmenu = new JPopupMenu("Menu"); menuItem = new JMenuItem("Sections"); Pmenu.add(menuItem); menuItem = new JMenuItem("Numbers"); Pmenu.add(menuItem); 但是,我想
Pmenu = new JPopupMenu("Menu");
menuItem = new JMenuItem("Sections");
Pmenu.add(menuItem);
menuItem = new JMenuItem("Numbers");
Pmenu.add(menuItem);
但是,我想将子菜单添加到这些菜单中,例如用户将鼠标悬停在“部分”菜单上,子菜单将打开并显示部分。将
JMenu
实例添加到jpopmpmenu
中。JMenu
当然应该包含JMenuItem
实例
有关Swing中菜单的教程,请参阅。首先,对象名称通常以小写字母开头,大写字母通常用于类/接口名称 对于您的问题,下面是子菜单的代码
//parent menu
JPopupMenu pmenu = new JPopupMenu("Menu");
//sub menu
JMenu sectionsMenu = new JMenu("Sections");
JMenuItem menuItem1 = new JMenuItem("Item1");
sectionsMenu .add(menuItem1 );
JMenuItem menuItem2 = new JMenuItem("Item2");
sectionsMenu .add(menuItem2 );
pmenu.add(sectionsMenu);
//regular menu item
menuItem = new JMenuItem("Numbers");
pmenu.add(menuItem);
或
}我在菜单栏中使用了JMenu,但是当用户右键单击时,我应该如何在确切位置显示该菜单?使用myPanel.setComponentPopupMenu(popupMenu),当您右键单击myPanel时,弹出菜单将出现。
public JMenuBar createMenuBar() {
JMenuBar menuBar;
JMenu menu, submenu;
JMenuItem menuItem;
JRadioButtonMenuItem rbMenuItem;
JCheckBoxMenuItem cbMenuItem;
//Create the menu bar.
menuBar = new JMenuBar();
//Build the first menu.
menu = new JMenu("A Menu");
menu.setMnemonic(KeyEvent.VK_A);
menu.getAccessibleContext().setAccessibleDescription(
"The only menu in this program that has menu items");
menuBar.add(menu);
//a group of JMenuItems
menuItem = new JMenuItem("A text-only menu item",
KeyEvent.VK_T);
//menuItem.setMnemonic(KeyEvent.VK_T); //used constructor instead
menuItem.setAccelerator(KeyStroke.getKeyStroke(
KeyEvent.VK_1, ActionEvent.ALT_MASK));
menuItem.getAccessibleContext().setAccessibleDescription(
"This doesn't really do anything");
menuItem.addActionListener(this);
menu.add(menuItem);
ImageIcon icon = createImageIcon("images/middle.gif");
menuItem = new JMenuItem("Both text and icon", icon);
menuItem.setMnemonic(KeyEvent.VK_B);
menuItem.addActionListener(this);
menu.add(menuItem);
menuItem = new JMenuItem(icon);
menuItem.setMnemonic(KeyEvent.VK_D);
menuItem.addActionListener(this);
menu.add(menuItem);
//a group of radio button menu items
menu.addSeparator();
ButtonGroup group = new ButtonGroup();
rbMenuItem = new JRadioButtonMenuItem("A radio button menu item");
rbMenuItem.setSelected(true);
rbMenuItem.setMnemonic(KeyEvent.VK_R);
group.add(rbMenuItem);
rbMenuItem.addActionListener(this);
menu.add(rbMenuItem);
rbMenuItem = new JRadioButtonMenuItem("Another one");
rbMenuItem.setMnemonic(KeyEvent.VK_O);
group.add(rbMenuItem);
rbMenuItem.addActionListener(this);
menu.add(rbMenuItem);
//a group of check box menu items
menu.addSeparator();
cbMenuItem = new JCheckBoxMenuItem("A check box menu item");
cbMenuItem.setMnemonic(KeyEvent.VK_C);
cbMenuItem.addItemListener(this);
menu.add(cbMenuItem);
cbMenuItem = new JCheckBoxMenuItem("Another one");
cbMenuItem.setMnemonic(KeyEvent.VK_H);
cbMenuItem.addItemListener(this);
menu.add(cbMenuItem);
//a submenu
menu.addSeparator();
submenu = new JMenu("A submenu");
submenu.setMnemonic(KeyEvent.VK_S);
menuItem = new JMenuItem("An item in the submenu");
menuItem.setAccelerator(KeyStroke.getKeyStroke(
KeyEvent.VK_2, ActionEvent.ALT_MASK));
menuItem.addActionListener(this);
submenu.add(menuItem);
menuItem = new JMenuItem("Another item");
menuItem.addActionListener(this);
submenu.add(menuItem);
menu.add(submenu);
//Build second menu in the menu bar.
menu = new JMenu("Another Menu");
menu.setMnemonic(KeyEvent.VK_N);
menu.getAccessibleContext().setAccessibleDescription(
"This menu does nothing");
menuBar.add(menu);
return menuBar;
}
public Container createContentPane() {
//Create the content-pane-to-be.
JPanel contentPane = new JPanel(new BorderLayout());
contentPane.setOpaque(true);
//Create a scrolled text area.
output = new JTextArea(5, 30);
output.setEditable(false);
scrollPane = new JScrollPane(output);
//Add the text area to the content pane.
contentPane.add(scrollPane, BorderLayout.CENTER);
return contentPane;
}
public void createPopupMenu() {
JMenuItem menuItem;
//Create the popup menu.
JPopupMenu popup = new JPopupMenu();
menuItem = new JMenuItem("A popup menu item");
menuItem.addActionListener(this);
popup.add(menuItem);
menuItem = new JMenuItem("Another popup menu item");
menuItem.addActionListener(this);
popup.add(menuItem);
//Add listener to the text area so the popup menu can come up.
MouseListener popupListener = new PopupListener(popup);
output.addMouseListener(popupListener);
}
public void actionPerformed(ActionEvent e) {
JMenuItem source = (JMenuItem)(e.getSource());
String s = "Action event detected."
+ newline
+ " Event source: " + source.getText()
+ " (an instance of " + getClassName(source) + ")";
output.append(s + newline);
output.setCaretPosition(output.getDocument().getLength());
}
public void itemStateChanged(ItemEvent e) {
JMenuItem source = (JMenuItem)(e.getSource());
String s = "Item event detected."
+ newline
+ " Event source: " + source.getText()
+ " (an instance of " + getClassName(source) + ")"
+ newline
+ " New state: "
+ ((e.getStateChange() == ItemEvent.SELECTED) ?
"selected":"unselected");
output.append(s + newline);
output.setCaretPosition(output.getDocument().getLength());
}
// Returns just the class name -- no package info.
protected String getClassName(Object o) {
String classString = o.getClass().getName();
int dotIndex = classString.lastIndexOf(".");
return classString.substring(dotIndex+1);
}
/** Returns an ImageIcon, or null if the path was invalid. */
protected static ImageIcon createImageIcon(String path) {
java.net.URL imgURL = PopupMenuDemo.class.getResource(path);
if (imgURL != null) {
return new ImageIcon(imgURL);
} else {
System.err.println("Couldn't find file: " + path);
return null;
}
}
/**
* Create the GUI and show it. For thread safety,
* this method should be invoked from the
* event-dispatching thread.
*/
private static void createAndShowGUI() {
//Create and set up the window.
JFrame frame = new JFrame("PopupMenuDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Create/set menu bar and content pane.
PopupMenuDemo demo = new PopupMenuDemo();
frame.setJMenuBar(demo.createMenuBar());
frame.setContentPane(demo.createContentPane());
//Create and set up the popup menu.
demo.createPopupMenu();
//Display the window.
frame.setSize(450, 260);
frame.setVisible(true);
}
public static void main(String[] args) {
//Schedule a job for the event-dispatching thread:
//creating and showing this application's GUI.
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
class PopupListener extends MouseAdapter {
JPopupMenu popup;
PopupListener(JPopupMenu popupMenu) {
popup = popupMenu;
}
public void mousePressed(MouseEvent e) {
maybeShowPopup(e);
}
public void mouseReleased(MouseEvent e) {
maybeShowPopup(e);
}
private void maybeShowPopup(MouseEvent e) {
if (e.isPopupTrigger()) {
popup.show(e.getComponent(),
e.getX(), e.getY());
}
}
}