带有 jPanel 的 jFrame答案

【问题标题】：jFrame with jPanel带有 jPanel 的 jFrame
【发布时间】：2018-07-30 14:40:20
【问题描述】：

你好，我实际上是在尝试从 jPanel 切换到我的 jFrame 中的另一个。我已经更改了我的代码，这就是它的样子我遵循了这个：

How to use CardLayout with Netbeans GUI Builder

我的主要：

 package testjframe;
public class TestJframe {
public static void main(String[] args) {
    new MyFrame().setVisible(true);
}

}

还有我的 jFrame：

 package testjframe;
import java.awt.CardLayout;
public class MyFrame extends javax.swing.JFrame {

public MyFrame() {
    initComponents();

}

   @SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">                          
private void initComponents() {

    mainPanel = new javax.swing.JPanel();
    panel2 = new javax.swing.JPanel();
    jLabel2 = new javax.swing.JLabel();
    panel1 = new javax.swing.JPanel();
    jLabel1 = new javax.swing.JLabel();
    panel3 = new javax.swing.JPanel();
    jLabel3 = new javax.swing.JLabel();
    btn1 = new javax.swing.JButton();
    btn2 = new javax.swing.JButton();
    btn3 = new javax.swing.JButton();

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

    mainPanel.setLayout(new java.awt.CardLayout());

    jLabel2.setText("jLabel2");

    javax.swing.GroupLayout panel2Layout = new javax.swing.GroupLayout(panel2);
    panel2.setLayout(panel2Layout);
    panel2Layout.setHorizontalGroup(
        panel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 792, Short.MAX_VALUE)
        .addGroup(panel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(panel2Layout.createSequentialGroup()
                .addGap(0, 0, Short.MAX_VALUE)
                .addComponent(jLabel2)
                .addGap(0, 0, Short.MAX_VALUE)))
    );
    panel2Layout.setVerticalGroup(
        panel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 460, Short.MAX_VALUE)
        .addGroup(panel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(panel2Layout.createSequentialGroup()
                .addGap(0, 0, Short.MAX_VALUE)
                .addComponent(jLabel2)
                .addGap(0, 0, Short.MAX_VALUE)))
    );

    mainPanel.add(panel2, "card3");

    jLabel1.setText("jLabel1");

    javax.swing.GroupLayout panel1Layout = new javax.swing.GroupLayout(panel1);
    panel1.setLayout(panel1Layout);
    panel1Layout.setHorizontalGroup(
        panel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 792, Short.MAX_VALUE)
        .addGroup(panel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(panel1Layout.createSequentialGroup()
                .addGap(0, 0, Short.MAX_VALUE)
                .addComponent(jLabel1)
                .addGap(0, 0, Short.MAX_VALUE)))
    );
    panel1Layout.setVerticalGroup(
        panel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 460, Short.MAX_VALUE)
        .addGroup(panel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(panel1Layout.createSequentialGroup()
                .addGap(0, 0, Short.MAX_VALUE)
                .addComponent(jLabel1)
                .addGap(0, 0, Short.MAX_VALUE)))
    );

    mainPanel.add(panel1, "card2");

    jLabel3.setText("jLabel3");

    javax.swing.GroupLayout panel3Layout = new javax.swing.GroupLayout(panel3);
    panel3.setLayout(panel3Layout);
    panel3Layout.setHorizontalGroup(
        panel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 792, Short.MAX_VALUE)
        .addGroup(panel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(panel3Layout.createSequentialGroup()
                .addGap(0, 0, Short.MAX_VALUE)
                .addComponent(jLabel3)
                .addGap(0, 0, Short.MAX_VALUE)))
    );
    panel3Layout.setVerticalGroup(
        panel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 460, Short.MAX_VALUE)
        .addGroup(panel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(panel3Layout.createSequentialGroup()
                .addGap(0, 0, Short.MAX_VALUE)
                .addComponent(jLabel3)
                .addGap(0, 0, Short.MAX_VALUE)))
    );

    mainPanel.add(panel3, "card4");

    btn1.setText("1");
    btn1.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            btn1ActionPerformed(evt);
        }
    });

    btn2.setText("2");
    btn2.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            btn2ActionPerformed(evt);
        }
    });

    btn3.setText("3");
    btn3.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            btn3ActionPerformed(evt);
        }
    });

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addContainerGap()
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addComponent(mainPanel, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addGroup(layout.createSequentialGroup()
                    .addComponent(btn1)
                    .addGap(261, 261, 261)
                    .addComponent(btn2)
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                    .addComponent(btn3)))
            .addContainerGap())
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addContainerGap()
            .addComponent(mainPanel, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 55, Short.MAX_VALUE)
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(btn1)
                .addComponent(btn3)
                .addComponent(btn2))
            .addContainerGap())
    );

    pack();
}// </editor-fold>                        

private void btn1ActionPerformed(java.awt.event.ActionEvent evt) {                                     
    // TODO add your handling code here:
    CardLayout card = (CardLayout)mainPanel.getLayout();
    card.show(mainPanel, "panel1");
    System.out.println("1");
}                                    

private void btn2ActionPerformed(java.awt.event.ActionEvent evt) {                                     
    // TODO add your handling code here:
    CardLayout card = (CardLayout) mainPanel.getLayout();
    card.show(mainPanel, "panel2");
    System.out.println("2");
}                                    

private void btn3ActionPerformed(java.awt.event.ActionEvent evt) {                                     
    // TODO add your handling code here:
    CardLayout card = (CardLayout)mainPanel.getLayout();
    card.show(mainPanel, "panel3");
    System.out.println("3");
}                                    

/**
 * @param args the command line arguments
 */
public static void main(String args[]) {
    /* Set the Nimbus look and feel */
    //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
    /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
    * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
    */
    try {
        for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
            if ("Nimbus".equals(info.getName())) {
                javax.swing.UIManager.setLookAndFeel(info.getClassName());
                break;
            }
        }
    } catch (ClassNotFoundException ex) {
        java.util.logging.Logger.getLogger(MyFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (InstantiationException ex) {
        java.util.logging.Logger.getLogger(MyFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (IllegalAccessException ex) {
        java.util.logging.Logger.getLogger(MyFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (javax.swing.UnsupportedLookAndFeelException ex) {
        java.util.logging.Logger.getLogger(MyFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    }
    //</editor-fold>
    //</editor-fold>

    /* Create and display the form */
    java.awt.EventQueue.invokeLater(new Runnable() {
        public void run() {
            new MyFrame().setVisible(true);
        }
    });
}

// Variables declaration - do not modify                     
private javax.swing.JButton btn1;
private javax.swing.JButton btn2;
private javax.swing.JButton btn3;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JLabel jLabel3;
private javax.swing.JPanel mainPanel;
private javax.swing.JPanel panel1;
private javax.swing.JPanel panel2;
private javax.swing.JPanel panel3;
// End of variables declaration

}

但它没有用，我错过了什么或做错了什么？

【问题讨论】：

您可以为面板类添加代码吗？您还可以确认正在调用btn1ActionPerformed 方法吗？如果您可以添加任何其他代码，例如添加按钮侦听器，那将有很大帮助。
@Michael btn1ActionPerformed 工作，我已经添加了 jPanel 类的代码
运行代码时会发生什么？结果与您想要的结果有何不同？花点时间阅读ericlippert.com/2014/03/05/how-to-debug-small-programs，了解有关如何调试代码的提示。
你有panelD的代码吗？
@Code-Apprentice 我的 jFrame 出现了，我已经将 System.out.print("test"; 应用到按钮上，当 clic 时，"test" 显示在控制台中，但我的 jPanel 没有改变

标签： java swing jpanel

【解决方案1】：

目前您正在重新绘制面板，然后重新验证。这意味着您重新绘制它以使其看起来相同，然后删除并添加组件。您需要在重组组件后重新绘制。

试试这个：

monPanel.removeAll();
monPanel.add(new panel1());
monPanel.revalidate();
monPanel.repaint();

【讨论】：

我已经更改了我的代码，如果你可以看看的话
从简单开始是个好主意吗？创建一个 JFrame 并添加一个带有标签和按钮的 JPanel。当按下按钮时，使其变为另一个包含不同标签的面板。如果你得到这个工作，你应该能够找出问题。
另外，我建议对您当前的代码进行一些更改以整理它。类名应该大写。变量通常应该在顶部声明。许多变量在声明时也可以初始化。最后，您可以使用导入来代替限定的类名。
这是我真正想要做的，1 个 jFrame 和 1 个 jPanel，在该面板 3 jPanel 内，我将尝试用 3 个按钮显示（每个面板一个）
目前你的代码很长。对于我们来说，最好有一个可以轻松运行和测试的小示例。