大家好我想创建一个简单的程序，我可以使用menuItems控制每个JPanel。例如，如果我选择File-＆gt; New，其中New是JmenuItem，它将显示名为newPanel的JPanel。此外，如果我选择Edit-＆gt; Edit，它将显示名为editPanel的JPanel以及添加到其中的对象。到目前为止，这是我构建的：
public class CardLayoutwithMenuBar extends JFrame implements ActionListener {
private JMenuBar menu;
private JMenu fileMenu;
private JMenu editMenu;
private JMenu exitMenu;
private JMenuItem openItem;
private JMenuItem newItem;
private JMenuItem editItem;
private JMenuItem exitItem;
private JPanel newPanel;
private JPanel openPanel;
private JPanel editPanel;
private JPanel exitPanel;
static private CardLayout cardView;
static private JPanel cardPanel;
public CardLayoutwithMenuBar(){
this.setVisible(true);
this.setTitle("Controlling Different Panel Using CardLayout");
this.setSize(400, 150);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Create Menu bar and add to Frame
menu = new JMenuBar();
this.setJMenuBar(menu);
fileMenu = new JMenu("File");
editMenu = new JMenu("Edit");
exitMenu = new JMenu("Exit");
menu.add(fileMenu);
menu.add(editMenu);
menu.add(exitMenu);
newItem = new JMenuItem("New File");
openItem = new JMenuItem("File Open");
editItem = new JMenuItem("Edit Entry");
exitItem = new JMenuItem("Exit");
fileMenu.add(newItem);
fileMenu.add(openItem);
editMenu.add(editItem);
exitMenu.add(exitItem);
//Declare object cardView and cardPanel and set layout of cardPanel to CardLayout
cardView = new CardLayout();
cardPanel = new JPanel();
cardPanel.setLayout(cardView);
//Create sub-panels that would correspond to each function in the menu item ex. newItem, openItem etc...
newPanel = new JPanel();
openPanel = new JPanel();
editPanel = new JPanel();
exitPanel = new JPanel();
//add the sub-panels to the main cardpanel
cardPanel.add("New", newPanel);
cardPanel.add("Open", openPanel);
cardPanel.add("Edit",editPanel);
cardPanel.add("Exit",exitPanel);
newItem.addActionListener(this);
openItem.addActionListener(this);
editItem.addActionListener(this);
exitItem.addActionListener(this);
this.getContentPane().add(cardPanel, BorderLayout.CENTER);
}
public void actionPerformed(ActionEvent evt){
String menuItemAction = evt.getActionCommand();
if (menuItemAction.equals("New File")){
cardView.show(newPanel, "New");
}
else if (menuItemAction.equals("File Open")){
cardView.show(openPanel, "Open");
}
else if (menuItemAction.equals("Edit Entry")){
cardView.show(editPanel, "Edit");
}
else if (menuItemAction.equals("Exit")){
cardView.show(exitPanel, "Exit");
}
else{
System.out.println("Opppsss you pressed something else");
}
}
}
当我尝试运行此程序时，我总是收到此错误：
Exception in thread "AWT-EventQueue-0" java.lang.IllegalArgumentException: wrong parent for CardLayout
at java.awt.CardLayout.checkLayout(CardLayout.java:404)
at java.awt.CardLayout.show(CardLayout.java:526)
at com.JMenuSample.CardLayoutwithMenuBar.actionPerformed(CardLayoutwithMenuBar.java:132)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2012)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2335)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:404)
.... and the list goes on
任何人都可以帮我解决这个问题吗？提前谢谢！
答案 0 :(得分：4)
必须使用CardLayout的正确方法 - public void show(Container parent, String name)
然后使用cardView.show(cardPanel, "New"); (insted of cardView.show(newPanel, "New");)
剩下的newPanel as Container留下来，只改变第二次。 String形式的参数
答案 1 :(得分：4)
+1到mKorbel（打败我）
然而这是：
setVisible之前不要致电JFrame。LayoutManager 的getPreferredSize或覆盖JComponent
pack()实例JFrame
switch上使用String阻止（来自java 7）而不是if语句，因为它更有效率extend JFrame课程错误的原因在于：
if (menuItemAction.equals("New File")){
cardView.show(newPanel, "New");
}
else if (menuItemAction.equals("File Open")){
cardView.show(openPanel, "Open");
}
else if (menuItemAction.equals("Edit Entry")){
cardView.show(editPanel, "Edit");
}
else if (menuItemAction.equals("Exit")){
cardView.show(exitPanel, "Exit");
}
else{
System.out.println("Opppsss you pressed something else");
}
您的父亲是您的cardPanel，而不是您要展示的面板，由字符串参数提供：
cardView.show(cardPanel, "New");
请参阅以下更改的代码：
import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class CardLayoutWithMenuBar implements ActionListener {
private JMenuBar menu;
private JMenu fileMenu;
private JMenu editMenu;
private JMenu exitMenu;
private JMenuItem openItem;
private JMenuItem newItem;
private JMenuItem editItem;
private JMenuItem exitItem;
private JPanel newPanel;
private JPanel openPanel;
private JPanel editPanel;
private JPanel exitPanel;
private CardLayout cardView;
private JPanel cardPanel;
public CardLayoutWithMenuBar() {
JFrame frame = new JFrame();
frame.setTitle("Controlling Different Panel Using CardLayout");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
initComponents(frame);
frame.pack();
frame.setVisible(true);
}
@Override
public void actionPerformed(ActionEvent evt) {
String menuItemAction = evt.getActionCommand();
switch (menuItemAction) {
case "New File":
cardView.show(cardPanel, "New");
break;
case "File Open":
cardView.show(cardPanel, "Open");
break;
case "Edit Entry":
cardView.show(cardPanel, "Edit");
break;
case "Exit":
cardView.show(cardPanel, "Exit");
break;
default:
System.out.println("Opppsss you pressed something else");
break;
}
}
private void initComponents(JFrame frame) {
//Create Menu bar and add to Frame
menu = new JMenuBar();
frame.setJMenuBar(menu);
fileMenu = new JMenu("File");
editMenu = new JMenu("Edit");
exitMenu = new JMenu("Exit");
menu.add(fileMenu);
menu.add(editMenu);
menu.add(exitMenu);
newItem = new JMenuItem("New File");
openItem = new JMenuItem("File Open");
editItem = new JMenuItem("Edit Entry");
exitItem = new JMenuItem("Exit");
fileMenu.add(newItem);
fileMenu.add(openItem);
editMenu.add(editItem);
exitMenu.add(exitItem);
//Declare object cardView and cardPanel and set layout of cardPanel to CardLayout
cardView = new CardLayout();
cardPanel = new JPanel(cardView);
//Create sub-panels that would correspond to each function in the menu item ex. newItem, openItem etc...
newPanel = new JPanel();
openPanel = new JPanel();
editPanel = new JPanel();
exitPanel = new JPanel();
//add the sub-panels to the main cardpanel
cardPanel.add("New", newPanel);
cardPanel.add("Open", openPanel);
cardPanel.add("Edit", editPanel);
cardPanel.add("Exit", exitPanel);
newItem.addActionListener(this);
openItem.addActionListener(this);
editItem.addActionListener(this);
exitItem.addActionListener(this);
frame.getContentPane().add(cardPanel, BorderLayout.CENTER);
}
public static void main(String... args) {
//create frame and components on EDT
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
CardLayoutWithMenuBar cardLayoutWithMenuBar = new CardLayoutWithMenuBar();
}
});
}
}