java 添加子菜单
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Adding a submenu
提问by Daniel D
So I tried to look at the Java docs for help for this but got confused pretty quickly. I am trying to add a submenu to the menu item 'Edit' which will have submenus Copy and Paste, and I'm note sure how to do it. I have a submenu variable created, do I use that? Please help, thank you. Code is below.
所以我试图查看 Java 文档以寻求帮助，但很快就感到困惑。我正在尝试向菜单项“编辑”添加一个子菜单，该菜单项将包含子菜单“复制和粘贴”，我知道如何执行此操作。我创建了一个子菜单变量，我可以使用它吗？请帮忙，谢谢。代码如下。
import javax.swing.JFrame;
import javax.swing.JMenuBar;
import javax.swing.JMenu;
import javax.swing.JMenuItem;
public class MyJFrame extends JFrame
{
JMenuBar menubar;
JMenu menu, submenu;
JMenuItem mi;
public MyJFrame(String title)
{
super(title);
menubar = new JMenuBar();
setJMenuBar(menubar);
buildMenu();
}
void buildMenu()
{
menu = new JMenu("File");
mi = new JMenuItem("New");
menu.add(mi);
menubar.add(menu);
mi = new JMenuItem("List Files");
menu.add(mi);
menubar.add(menu);
menu.addSeparator();
mi = new JMenuItem("Save As");
menu.add(mi);
menubar.add(menu);
menu.addSeparator();
mi = new JMenuItem("Close");
menu.add(mi);
menubar.add(menu);
menu = new JMenu("Tools");
mi = new JMenuItem("Sort");
menu.add(mi);
menubar.add(menu);
mi = new JMenuItem("Search");
menu.add(mi);
menubar.add(menu);
mi = new JMenuItem("Edit");
menu.add(mi);
menubar.add(menu);
mi = new JMenuItem("Copy");
menu.add(mi);
menubar.add(menu);
mi = new JMenuItem("Paste");
menu.add(mi);
menubar.add(menu);
}
}
回答by Sharad Ag.
create a Menu instead of a MenuItem for Edit, and add MenuItems Copy and Paste. Then Add edit menu to Tools Menu .
为 Edit 创建一个 Menu 而不是 MenuItem，并添加 MenuItems Copy 和 Paste。然后将编辑菜单添加到工具菜单。
menu = new JMenu("Tools");
mi = new JMenuItem("Sort");
menu.add(mi);
mi = new JMenuItem("Search");
menu.add(mi);
JMenu med = new JMenu("Edit");
mi = new JMenuItem("Copy");
med.add(mi);
mi = new JMenuItem("Paste");
med.add(mi);
menu.add(med);
menubar.add(menu);
Note: I have edited the last part of your code. Just replace the code from tools menu to this and try this. If it gets error, tell me.
注意：我已经编辑了您代码的最后一部分。只需将工具菜单中的代码替换为这个，然后试试这个。如果出现错误，请告诉我。
回答by Sharad Ag.
Here is a simple example of how you can do it:
这是一个简单的例子，说明如何做到这一点：
JMenuBar menuBar = new JMenuBar();
// Edit Menu
JMenu editMenu = new JMenu("Edit");
menuBar.add(editMenu);
// Edit -> Copy
JMenuItem copyMenuItem = new JMenuItem("Copy");
editMenu.add(copyMenuItem);
// Edit -> Paste
JMenuItem pasteMenuItem = new JMenuItem("Paste");
editMenu.add(pasteMenuItem);
回答by Arthur Spooner
Simplified excerpt from https://docs.oracle.com/javase/tutorial/uiswing/components/menu.html
摘自https://docs.oracle.com/javase/tutorial/uiswing/components/menu.html
menu.addSeparator();
submenu = new JMenu("A submenu");
menuItem = new JMenuItem("An item in the submenu");
submenu.add(menuItem);
menuItem = new JMenuItem("Another item");
submenu.add(menuItem);
menu.add(submenu); // you add the submenu to your existing menu
