我无法让 CardLayout 使用按钮切换卡片答案

【问题标题】：I can't get my CardLayout to switch cards using a button我无法让 CardLayout 使用按钮切换卡片
【发布时间】：2014-11-05 16:12:24
【问题描述】：

我试图让 CardLayout 使用按钮更改面板的内容（用于不同类中的内容），但由于某种原因，按钮（添加新项目）在单击时没有任何作用。

“添加新项目”按钮的事件侦听器正在尝试访问不同的类（NewProject 类）

    ...
//CardLayout variables
private JPanel cardPanel;
private static final String CARD_PROJECTTAB = "Card Project Tab";
private static final String CARD_NEWPROJECT = "Card Add Project";
private NewProject newProject;
//private TabPanel tp = new TabPanel();

//

public ProTab(){

//Create cardPanel the panel that holds all the cards.
cardPanel = new JPanel();
cardPanel.setLayout(new CardLayout(0,3));       

//Creating the proPanel that holds all other panels (below cardPanel)
proPanel = new JPanel();
proPanel.setBackground(new Color(204, 255, 102));


/*
  ==========================
  CardLayout Class Instances
  ==========================
*/

cardPanel.add(proPanel, CARD_PROJECTTAB);
newProject = new NewProject();
cardPanel.add(newProject, CARD_NEWPROJECT);

//Creating the contentPane that holds all GUI components and
//uses vertical/horizontal sidebars as needed
contentPane = new JPanel();
contentPane.setBackground(Color.WHITE);

//Giving the contentPane the GridBagLayout
contentPane.setLayout(new GridBagLayout());
GridBagConstraints g = new GridBagConstraints();
g.insets = new Insets(20,0,0,0);

...

//Project bottom buttons START

 bButtonsPanel = new JPanel();
 bButtonsPanel.setBackground(Color.WHITE);
 bButtonsPanel.setBorder(BorderFactory.createMatteBorder(0,0,0,0, Color.gray));
 bButtonsPanel.setLayout(new FlowLayout());
    g.anchor = GridBagConstraints.PAGE_END;
    g.gridx = 0;
    g.gridy = 2;
    contentPane.add(bButtonsPanel, g);

viewProjectButton = new JButton("View Selected Project");
addProjectButton = new JButton ("Add a New Project");

bButtonsPanel.add(viewProjectButton);
bButtonsPanel.add(addProjectButton);

addProjectButton.addActionListener(new buttonListener());

//Project bottom buttons END

}

//Project bottom buttons ActionListeners
private class buttonListener implements ActionListener{
    public void actionPerformed(ActionEvent ae){
        if (ae.getSource() == addProjectButton){
        CardLayout cl = (CardLayout) cardPanel.getLayout();
        cl.show(cardPanel, CARD_NEWPROJECT);
        }
    }
 }

【问题讨论】：

标签： java user-interface cardlayout

【解决方案1】：

我想通了。我的错误不在于 CardLayout 的实现，而是我未能从另一个 c 正确调用包含 CardLayout 的 JPanel

Before //getProTab() 是一个返回带有 Project Tab 元素的 JPanel 的方法。

    pt = new ProTab();
    tabPane.addTab("Projects", pt.getProTab());
    tabPane.setBackgroundAt(2, (new Color(204, 255, 102)));

在 //getCardPanel() 之后是我创建的一个新方法，用于返回包含所有卡片的 JPanel（包括 // proPanel 面板）

    pt = new ProTab();
    tabPane.addTab("Projects", pt.getCardPanel());
    tabPane.setBackgroundAt(2, (new Color(204, 255, 102)));

【讨论】：