java - JPanel 调整大小显示另一个 JPanel

Question

我对嵌套的 BoxLayouts 有疑问。

我想构建一个由 2 个子面板组成的 DropDownPanel:顶部的标题和底部的主体。 body 最初是隐藏的。通过单击标题，您可以切换正文的可见性并显示其内容(如展开/折叠)。

总的来说，这很好用。但是有一些奇怪的行为:
如果只有一个 DropDownPanel 展开而另一个折叠，则折叠的 DropDownPanel 会调整大小并向右浮动。

我已经试验过 JPanel 的属性，如 alignmentX，但我找不到我的错误。有谁知道我做错了什么？

代码如下:
DropDownPanel.java

public class DropDownPanel extends javax.swing.JPanel {

    private boolean mShowContent = false;

    /**
     * Creates new form DropDownPanel
     */
    public DropDownPanel() {
        initComponents();
        showContent(mShowContent);
    }

    private void showContent(boolean showContent) {
        mShowContent = showContent;
        System.out.println(mShowContent? "show" : "hide");
        body.setVisible(mShowContent);
        revalidate();
    }

    /**
     * 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">//GEN-BEGIN:initComponents
    private void initComponents() {

        jPanel3 = new javax.swing.JPanel();
        header = new javax.swing.JPanel();
        jLabel1 = new javax.swing.JLabel();
        body = new javax.swing.JPanel();
        jPanel5 = new javax.swing.JPanel();
        jLabel2 = new javax.swing.JLabel();

        setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 0, 0)));
        setLayout(new javax.swing.BoxLayout(this, javax.swing.BoxLayout.Y_AXIS));

        jPanel3.setLayout(new javax.swing.BoxLayout(jPanel3, javax.swing.BoxLayout.Y_AXIS));

        header.setMaximumSize(new java.awt.Dimension(32000, 60));
        header.setMinimumSize(new java.awt.Dimension(0, 60));
        header.setPreferredSize(new java.awt.Dimension(0, 60));
        header.addMouseListener(new java.awt.event.MouseAdapter() {
            public void mouseClicked(java.awt.event.MouseEvent evt) {
                headerMouseClicked(evt);
            }
        });
        header.setLayout(new javax.swing.BoxLayout(header, javax.swing.BoxLayout.X_AXIS));

        jLabel1.setText("Click Me!");
        header.add(jLabel1);

        jPanel3.add(header);

        body.setLayout(new javax.swing.BoxLayout(body, javax.swing.BoxLayout.Y_AXIS));

        jPanel5.setLayout(new javax.swing.BoxLayout(jPanel5, javax.swing.BoxLayout.X_AXIS));

        jLabel2.setText("jLabel2");
        jPanel5.add(jLabel2);

        body.add(jPanel5);

        jPanel3.add(body);

        add(jPanel3);
    }// </editor-fold>//GEN-END:initComponents

    private void headerMouseClicked(java.awt.event.MouseEvent evt) {//GEN-FIRST:event_headerMouseClicked
        System.out.println("asd");
        showContent(!mShowContent);
    }//GEN-LAST:event_headerMouseClicked
    // Variables declaration - do not modify//GEN-BEGIN:variables
    private javax.swing.JPanel body;
    private javax.swing.JPanel header;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JPanel jPanel3;
    private javax.swing.JPanel jPanel5;
    // End of variables declaration//GEN-END:variables
}

测试框架.java

public class TestFrame extends javax.swing.JFrame {

    /**
     * Creates new form TestFrame
     */
    public TestFrame() {
        initComponents();
        jPanel1.add(new DropDownPanel());
        jPanel1.add(new DropDownPanel());
        revalidate();
    }

    /**
     * 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">//GEN-BEGIN:initComponents
    private void initComponents() {

        jScrollPane1 = new javax.swing.JScrollPane();
        jPanel1 = new javax.swing.JPanel();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setMinimumSize(new java.awt.Dimension(400, 300));

        jPanel1.setLayout(new javax.swing.BoxLayout(jPanel1, javax.swing.BoxLayout.Y_AXIS));
        jScrollPane1.setViewportView(jPanel1);

        getContentPane().add(jScrollPane1, java.awt.BorderLayout.CENTER);

        pack();
    }// </editor-fold>//GEN-END:initComponents

    /**
     * @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(TestFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(TestFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(TestFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(TestFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        /*
         * Create and display the form
         */
        java.awt.EventQueue.invokeLater(new Runnable() {

            public void run() {
                new TestFrame().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify//GEN-BEGIN:variables
    private javax.swing.JPanel jPanel1;
    private javax.swing.JScrollPane jScrollPane1;
    // End of variables declaration//GEN-END:variables
}

Answer 1

从你的问题中不确定你是...

• Accordion

或

• Expand/Collapsing JPanels

或

• Ribbon (仅限 Substance 外观)