Java CardLayout主菜单问题

好的，所以即时通讯工作在java中称为8位嵌合体。 我现在在主菜单上工作但是当我使用卡片布局时，窗口由于某种原因不会打开。 这是一些代码。

import javax.swing.*; import java.awt.*; public class MainScreen extends JFrame{ String Title = "MainMenu"; MainMenuComp MMC = new MainMenuComp(); BreedingGround BGR = new BreedingGround(); public MainScreen() { setTitle("8-bit Chimera "+Title); setSize(800,600); setResizable(false); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); setVisible(true); add(MMC); add(BGR); } public static void main(String[] args){ new MainScreen(); } } 

那是主窗口

 import javax.swing.*; import java.awt.*; import java.awt.event.*; public class MainMenuComp extends JPanel implements ActionListener{ BreedingGround BGR = new BreedingGround(); ImageData ID = new ImageData(); Image TitleBg; Image Title; CardLayout CL; JButton Play; public MainMenuComp() { setLayout(new GridBagLayout()); GridBagConstraints GBC = new GridBagConstraints(); ImageIcon TitleData = new ImageIcon(ID.TitleSource); ImageIcon TitleBackGroundData = new ImageIcon(ID.TitleBackGroundSource); ImageIcon PlayData = new ImageIcon(ID.PlaySource); TitleBg = TitleBackGroundData.getImage(); Title = TitleData.getImage(); Play = new JButton(); Play.setIcon(PlayData); add(Play,GBC); add(BGR,"Breed"); } public void actionPerformed(ActionEvent AE){ if(AE.getSource() == Play){ CL.show(this, "Breed"); } } public void paintComponent(Graphics g){ g.drawImage(TitleBg,0,0,800,600,this); g.drawImage(Title,250,80,280,140,this); } } 

这是卡片布局

 import javax.swing.*; import java.awt.*; public class BreedingGround extends JPanel{ ImageData ID = new ImageData(); Image Swamp; CardLayout CL; public BreedingGround(){ setLayout(new GridBagLayout()); GridBagConstraints c = new GridBagConstraints(); ImageIcon SwampData = new ImageIcon(ID.SwampSource); Swamp = SwampData.getImage(); } public void paintComponent(Graphics g){ g.drawImage(Swamp,0,0,800,600,this); } } 

这就是我想要CardLayout打开的原因。 问题是，当我尝试运行它时，窗口不会运行，这将继续在编译器中显示。

——————–配置：8位嵌合体 – JDK版本1.6.0_26 – —————– —

 Exception in thread "main" java.lang.IllegalArgumentException: cannot add to layout: constraints must be a GridBagConstraint at java.awt.GridBagLayout.addLayoutComponent(GridBagLayout.java:685) at java.awt.Container.addImpl(Container.java:1074) at java.awt.Container.add(Container.java:927) at MainMenuComp.(MainMenuComp.java:26) at MainScreen.(MainScreen.java:7) at MainScreen.main(MainScreen.java:23) 

流程已完成。

我真正想知道的是这是什么意思。

Answer 1

我没有看到你在哪里设置容器的布局是CardLayout，如果你没有设置布局，你不能神奇地使用它。 如果您尚未完成CardLayout教程 ，请考虑这样做，因为它在那里都有解释。

编辑1
Alexander Kim的评论：

当我添加cardbagLayout它不会加载图像和按钮大小填充整个屏幕。 我也带走了网格

您需要嵌套JPanel以嵌套布局。 使用单个JPanel作为CardLayout容器，其单个function是显示其他JPanel（“卡”）。 这些其他JPanel将使用正确显示它们所持有的组件所需的任何布局，例如JButton或“网格”（无论它们是什么）。 甚至这些JPanels也可能拥有其他使用其他布局的JPanel。

再次，请阅读布局教程，因为它在那里都很好。 你不会后悔这样做。

编辑2
这是一个使用CardLayout的非常简单的示例。 CardLayout使用JPanel（称为cardContainer）显示的组件根据combobox中选择的项目而更改。

这是CardLayout和使用它的JPanel：

私人CardLayout cardLayout = new CardLayout（）;

  // *** JPanel to hold the "cards" and to use the CardLayout: private JPanel cardContainer = new JPanel(cardLayout); 

以下是我使用JPanel向cardlayout添加组件的方法：

  JPanel redPanel = new JPanel(); //... String red = "Red Panel"; cardContainer.add(redPanel, red); // add the JPanel to the container with the String 

我还将字符串添加到JComboBox，以便稍后使用此combobox告诉CardLayout显示此JPanel（redPanel），如果用户在同一个JComboBox中选择“Red”项：

  cardCombo.addItem(red); // also add the String to the JComboBox 

这是JComboBox中的ActionListener，它允许我使用JPanel更改cardlayout中显示的项目：

  cardCombo.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { String item = cardCombo.getSelectedItem().toString(); // *** if combo box changes it tells the CardLayout to // *** swap views based on the item selected in the combo box: cardLayout.show(cardContainer, item); } }); 

这是整个shebang：

 import java.awt.*; import java.awt.event.*; import javax.swing.*; public class SimpleCardLayoutDemo { private CardLayout cardLayout = new CardLayout(); // *** JPanel to hold the "cards" and to use the CardLayout: private JPanel cardContainer = new JPanel(cardLayout); private JComboBox cardCombo = new JComboBox(); private JPanel comboPanel = new JPanel();; public SimpleCardLayoutDemo() { JPanel greenPanel = new JPanel(new BorderLayout()); greenPanel.setBackground(Color.green); greenPanel.add(new JScrollPane(new JTextArea(10, 25)), BorderLayout.CENTER); greenPanel.setBorder(BorderFactory.createEmptyBorder(15, 15, 15, 15)); greenPanel.add(new JButton("Bottom Button"), BorderLayout.PAGE_END); String green = "Green Panel"; cardContainer.add(greenPanel, green); cardCombo.addItem(green); JPanel redPanel = new JPanel(); redPanel.setBackground(Color.red); redPanel.add(new JButton("Foo")); redPanel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5)); String red = "Red Panel"; cardContainer.add(redPanel, red); cardCombo.addItem(red); JPanel bluePanel = new JPanel(); bluePanel.setBackground(Color.blue); JLabel label = new JLabel("Blue Panel", SwingConstants.CENTER); label.setForeground(Color.white); label.setFont(label.getFont().deriveFont(Font.BOLD, 32f)); bluePanel.add(label); String blue = "Blue Panel"; cardContainer.add(bluePanel, blue); cardCombo.addItem(blue); comboPanel.add(cardCombo); cardCombo.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { String item = cardCombo.getSelectedItem().toString(); // *** if combo box changes it tells the CardLayout to // *** swap views based on the item selected in the combo box: cardLayout.show(cardContainer, item); } }); } public JPanel getCardContainerPanel() { return cardContainer; } public Component getComboPanel() { return comboPanel ; } private static void createAndShowUI() { SimpleCardLayoutDemo simplecardDemo = new SimpleCardLayoutDemo(); JFrame frame = new JFrame("Simple CardLayout Demo"); frame.getContentPane().add(simplecardDemo.getCardContainerPanel(), BorderLayout.CENTER); frame.getContentPane().add(simplecardDemo.getComboPanel(), BorderLayout.PAGE_END); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.pack(); frame.setLocationRelativeTo(null); frame.setVisible(true); } // to run Swing in a thread-safe way public static void main(String[] args) { java.awt.EventQueue.invokeLater(new Runnable() { public void run() { createAndShowUI(); } }); } } 

Answer 2

你的问题是add(BGR,"Breed"); 。 MainMenuComp的布局是GridBagLayout ，因此约束必须是GridBagConstraint ，而不是String （您有"Breed"作为约束）。