Java Swing 重新打包组件答案

【问题标题】：Java Swing repack componentsJava Swing 重新打包组件
【发布时间】：2013-10-08 23:16:35
【问题描述】：

我在使用卡片布局时遇到了打包功能的问题。我创建了 1 个 JFrame，其中包括 JPanel（在卡片布局中），这个 JPanel 包含两个 JPanel。 ...所以当我运行我的程序时，窗口的大小会调整为程序中最大的 JPanel，我无法动态调整它的大小。

现在屏幕：当我仅使用此面板运行程序时，我的背景 1（较小的背景）类的宽度为 200 http://i41.tinypic.com/scfi88.jpg 当我运行添加了 background2 的程序时，背景会得到它的宽度，所以它看起来像 400 http://i41.tinypic.com/2lu742x.jpg 所以它得到了我的 background2 面板的宽度

在两个背景类中，我都有返回预览背景的按钮，但它从不调整大小。我已经在这些操作按钮上使用了重新验证和重新绘制功能。代码：主班和背景1和 background2（背景代码很大，因为它们是由netbeans设计模式生成的（它们只是几个空组件）：

public class main extends javax.swing.JFrame {

private JPanel mainPanel;

public main() {
    mainPanel = new JPanel(new CardLayout());
    add(mainPanel);

    Background2 card1 = new Background2(mainPanel);
    Background1 card2 = new Background1(mainPanel);
    mainPanel.add(card1,"card1");
    mainPanel.add(card2,"card2");
    CardLayout cl = (CardLayout) (mainPanel.getLayout());
    cl.show(mainPanel, "card1");
    mainPanel.revalidate();
    mainPanel.repaint();
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    pack();
}
public static void main(String args[]) {
    java.awt.EventQueue.invokeLater(new Runnable() {
        public void run() {
            new main().setVisible(true);
        }
    });
}
}



public class Background1 extends javax.swing.JPanel {


private JPanel mainPanel;
/**
 * Creates new form HomePanel
 */
public Background1(JPanel panel) {
    mainPanel=panel;
    initComponents();
}


public JPanel getMainPanel() {
    return mainPanel;
}

public void setMainPanel(JPanel mainPanel) {
    this.mainPanel = mainPanel;
}
/**
 * This method is called from within the constructor to initialize the form.
 * WARNING: Do NOT modify this code. The content of this method is always
 * regenerated by the Form Editor.
 */
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">                          
private void initComponents() {

    jScrollPane1 = new javax.swing.JScrollPane();
    jTable1 = new javax.swing.JTable();
    left_Panel = new javax.swing.JPanel();
    zakladka1_Button = new javax.swing.JButton();
    background_Panel = new javax.swing.JPanel();
    jScrollPane2 = new javax.swing.JScrollPane();
    jTable2 = new javax.swing.JTable();
    powrot_Button = new javax.swing.JButton();
    jLabel1 = new javax.swing.JLabel();
    jScrollPane3 = new javax.swing.JScrollPane();
    jTable3 = new javax.swing.JTable();

    jTable1.setModel(new javax.swing.table.DefaultTableModel(
        new Object [][] {
            {null, null, null, null},
            {null, null, null, null},
            {null, null, null, null},
            {null, null, null, null}
        },
        new String [] {
            "Title 1", "Title 2", "Title 3", "Title 4"
        }
    ));
    jScrollPane1.setViewportView(jTable1);

    zakladka1_Button.setText("button");
    zakladka1_Button.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            zakladka1_ButtonActionPerformed(evt);
        }
    });

    javax.swing.GroupLayout left_PanelLayout = new javax.swing.GroupLayout(left_Panel);
    left_Panel.setLayout(left_PanelLayout);
    left_PanelLayout.setHorizontalGroup(
        left_PanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(left_PanelLayout.createSequentialGroup()
            .addContainerGap()
            .addComponent(zakladka1_Button)
            .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
    );
    left_PanelLayout.setVerticalGroup(
        left_PanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(left_PanelLayout.createSequentialGroup()
            .addGap(5, 5, 5)
            .addComponent(zakladka1_Button)
            .addGap(433, 433, 433))
    );

    jTable2.setModel(new javax.swing.table.DefaultTableModel(
        new Object [][] {
            {null, null, null, null},
            {null, null, null, null},
            {null, null, null, null},
            {null, null, null, null}
        },
        new String [] {
            "Title 1", "Title 2", "Title 3", "Title 4"
        }
    ));
    jScrollPane2.setViewportView(jTable2);

    javax.swing.GroupLayout background_PanelLayout = new javax.swing.GroupLayout(background_Panel);
    background_Panel.setLayout(background_PanelLayout);
    background_PanelLayout.setHorizontalGroup(
        background_PanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(background_PanelLayout.createSequentialGroup()
            .addGap(32, 32, 32)
            .addComponent(jScrollPane2, javax.swing.GroupLayout.PREFERRED_SIZE, 452, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addContainerGap(83, Short.MAX_VALUE))
    );
    background_PanelLayout.setVerticalGroup(
        background_PanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, background_PanelLayout.createSequentialGroup()
            .addContainerGap(14, Short.MAX_VALUE)
            .addComponent(jScrollPane2, javax.swing.GroupLayout.PREFERRED_SIZE, 319, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addContainerGap())
    );

    powrot_Button.setText("<--");
    powrot_Button.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            powrot_ButtonActionPerformed(evt);
        }
    });

    jLabel1.setText("jLabel1");

    jTable3.setModel(new javax.swing.table.DefaultTableModel(
        new Object [][] {
            {null, null, null, null},
            {null, null, null, null},
            {null, null, null, null},
            {null, null, null, null}
        },
        new String [] {
            "Title 1", "Title 2", "Title 3", "Title 4"
        }
    ));
    jScrollPane3.setViewportView(jTable3);

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(this);
    this.setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
        .addGroup(javax.swing.GroupLayout.Alignment.LEADING, layout.createSequentialGroup()
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addComponent(left_Panel, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGroup(layout.createSequentialGroup()
                    .addGap(21, 21, 21)
                    .addComponent(powrot_Button)))
            .addGap(18, 18, 18)
            .addComponent(background_Panel, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addComponent(jScrollPane3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addComponent(jLabel1)
            .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addGap(18, 18, 18)
            .addComponent(powrot_Button, javax.swing.GroupLayout.PREFERRED_SIZE, 43, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
            .addComponent(left_Panel, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
        .addGroup(layout.createSequentialGroup()
            .addComponent(background_Panel, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addGap(0, 0, Short.MAX_VALUE))
        .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
            .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                    .addComponent(jLabel1)
                    .addGap(115, 115, 115))
                .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                    .addComponent(jScrollPane3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addGap(42, 42, 42))))
    );
}// </editor-fold>                        

private void powrot_ButtonActionPerformed(java.awt.event.ActionEvent evt) {                                              
    CardLayout cl = (CardLayout) (mainPanel.getLayout());
    cl.show(mainPanel, "card1");
    mainPanel.revalidate();
    mainPanel.repaint();
}                                             

private void zakladka1_ButtonActionPerformed(java.awt.event.ActionEvent evt) {                                                 

}                                                



// Variables declaration - do not modify                     
private javax.swing.JPanel background_Panel;
private javax.swing.JLabel jLabel1;
private javax.swing.JScrollPane jScrollPane1;
private javax.swing.JScrollPane jScrollPane2;
private javax.swing.JScrollPane jScrollPane3;
private javax.swing.JTable jTable1;
private javax.swing.JTable jTable2;
private javax.swing.JTable jTable3;
private javax.swing.JPanel left_Panel;
private javax.swing.JButton powrot_Button;
private javax.swing.JButton zakladka1_Button;
// End of variables declaration                   
}

public class Background2 extends javax.swing.JPanel {


private JPanel mainPanel;

public Background2(JPanel panel) {
    mainPanel=panel;
    initComponents();  
}

/**
 * This method is called from within the constructor to initialize the form.
 * WARNING: Do NOT modify this code. The content of this method is always
 * regenerated by the Form Editor.
 */
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">                          
private void initComponents() {

    loginFieldLabel = new javax.swing.JLabel();
    zalogujButton = new javax.swing.JButton();
    loginField = new javax.swing.JTextField();
    passwordField = new javax.swing.JPasswordField();
    logowanieLabel = new javax.swing.JLabel();
    passwordFieldLabel = new javax.swing.JLabel();
    jButton1 = new javax.swing.JButton();

    loginFieldLabel.setText("Login");

    zalogujButton.setText("Zaloguj");
    zalogujButton.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            zalogujButtonActionPerformed(evt);
        }
    });

    loginField.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            loginFieldActionPerformed(evt);
        }
    });

    passwordField.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            passwordFieldActionPerformed(evt);
        }
    });

    logowanieLabel.setText("Logowanie");

    passwordFieldLabel.setText("Hasło");

    jButton1.setText("jButton1");
    jButton1.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            jButton1ActionPerformed(evt);
        }
    });

    org.jdesktop.layout.GroupLayout layout = new org.jdesktop.layout.GroupLayout(this);
    this.setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(org.jdesktop.layout.GroupLayout.TRAILING)
        .add(layout.createSequentialGroup()
            .addContainerGap(org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
            .add(zalogujButton)
            .add(149, 149, 149))
        .add(org.jdesktop.layout.GroupLayout.LEADING, layout.createSequentialGroup()
            .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.TRAILING)
                .add(org.jdesktop.layout.GroupLayout.LEADING, layout.createSequentialGroup()
                    .addContainerGap()
                    .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
                        .add(logowanieLabel)
                        .add(layout.createSequentialGroup()
                            .add(56, 56, 56)
                            .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
                                .add(passwordFieldLabel)
                                .add(loginFieldLabel))
                            .add(26, 26, 26)
                            .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING, false)
                                .add(loginField)
                                .add(passwordField, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, 193, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)))))
                .add(org.jdesktop.layout.GroupLayout.LEADING, layout.createSequentialGroup()
                    .add(105, 105, 105)
                    .add(jButton1)))
            .addContainerGap(190, Short.MAX_VALUE))
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
        .add(layout.createSequentialGroup()
            .addContainerGap()
            .add(logowanieLabel)
            .add(29, 29, 29)
            .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.BASELINE)
                .add(loginField, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)
                .add(loginFieldLabel))
            .add(28, 28, 28)
            .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.BASELINE)
                .add(passwordFieldLabel)
                .add(passwordField, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE))
            .add(33, 33, 33)
            .add(zalogujButton)
            .addPreferredGap(org.jdesktop.layout.LayoutStyle.UNRELATED)
            .add(jButton1)
            .addContainerGap(101, Short.MAX_VALUE))
    );
}// </editor-fold>                        

private void zalogujButtonActionPerformed(java.awt.event.ActionEvent evt) {                                              

}                                             

private void loginFieldActionPerformed(java.awt.event.ActionEvent evt) {                                           
    // TODO add your handling code here:
}                                          

private void passwordFieldActionPerformed(java.awt.event.ActionEvent evt) {                                              
    // TODO add your handling code here:
}                                             

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
    CardLayout cl = (CardLayout) (mainPanel.getLayout());
    cl.show(mainPanel, "card2");
    mainPanel.revalidate();
    mainPanel.repaint();
}                                        



// Variables declaration - do not modify                     
private javax.swing.JButton jButton1;
private javax.swing.JTextField loginField;
private javax.swing.JLabel loginFieldLabel;
private javax.swing.JLabel logowanieLabel;
private javax.swing.JPasswordField passwordField;
private javax.swing.JLabel passwordFieldLabel;
private javax.swing.JButton zalogujButton;
// End of variables declaration                   
}

编辑：

CardLayout cl = (CardLayout) (mainPanel.getLayout());
cl.show(mainPanel, "card1");
l.preferredLayoutSize(mainPanel);//l = ShowingSizeCardLayout i added here prints on dim.width and dim.height 
mainPanel.revalidate();

输出：

width: 509
height: 323
width: 1203
height: 537

但它始终是 509 323。

【问题讨论】：

如需尽快获得更好的帮助，请发帖 SSCCE。（一个源文件，不是 3 个。）顺便说一句 - 对于屏幕截图，PNG 比 JPG 更好。请参阅How do I create screenshots?（有关制作出色屏幕截图的提示）。
好的，我修复了一点代码。关于图片，我没有足够的声誉来使用该功能。谢谢建议。
“关于我没有足够的声誉来使用该功能的图片” 我提供的链接几乎与将图片发布到网站和一切用于制作可以上传到此站点、任何其他图像站点或用于记录程序本身的出色图像。请再读一遍，这次更仔细。至于将图像上传到 this 站点 (SO)，如果它们不是 JPEG，它们的字节数会更小，我会为你完成的。
顺便说一句 - 取出来源之间的空间并使整个帖子成为“一个文本区域”并不是我的意思。如果您复制/粘贴该烂摊子，它将无法编译（如果您不相信我，请尝试一下）。运行时问题的 SSCCE 应该为每个人编译。请仔细阅读文档..

标签： java swing jpanel layout-manager cardlayout

【解决方案1】：

CardLayout 的默认行为是设置容器的首选尺寸为显示尺寸和插图的组件。

你应该继承 CardLayout 并覆盖 preferredLayoutSize方法：

class ShowingSizeCardLayout extends CardLayout {

    public Dimension preferredLayoutSize(Container container) {

        Insets insets = container.getInsets();

        Dimension dim = null;

        for (Component component : container.getComponents()) {
            if (component.isVisible()) {
                dim = component.getPreferredSize();
            }
        }

        dim.width += insets.left + insets.right;
        dim.height += insets.top + insets.bottom;

        return dim;

    }
}

这样就可以了，但是添加代码来检查空指针。

【讨论】：

嗯差不多了。当我运行程序时，面板被调整为更小的 JPanel。当我更改为第二个更大的面板时，宽度尺寸会变小。所以之前的 200 是 400，现在是 400 200。我在换卡时开始调用这个 prefferedsizefuncion，它似乎计算出很好的宽度和高度，但 jpanel 没有调整大小（代码在“编辑”之后的第一篇文章中）跨度>
你不应该打电话给preferredLayoutSize。应该由布局管理器执行此操作。框架，因此，具有卡片布局的面板将具有第一个“面板卡片”的大小。如果您更改显示卡，则框架和主面板不应自动调整大小，即使首选大小已更改。在preferredLayoutSize 中，您设置的是首选大小，而不是当前大小。如果要将框架调整为首选大小，请调用pack 方法。同样，不要打电话给preferredLayoutSize。
大成功！！非常感谢。使用带有 fram.pack() 覆盖的 CardLayout 解决了我的问题！ @Andrew Thompson 问题已解决，所以我不会编辑第一篇文章，抱歉；p
再一个q。例如，如果我动态创建表并添加 10 行会怎样？我应该以同样的方式调用 preferreflayoutsize 方法然后打包？
你不应该打电话给preferredLayoutSize。当您调用 pack 时，布局管理器会执行此操作。