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。身体最初是隐藏的。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）。
一般来说这很好用。但是有一些奇怪的行为：
如果只展开了一个DropDownPanel而另一个被折叠，则折叠的DropDownPanel会调整大小并浮动到右侧。
我已经尝试了像alignmentX这样的JPanel属性，但我找不到我的错误。 有谁知道我做错了什么？
这是代码：
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
}
TestFrame.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
}
答案 0 :(得分：3)
答案 1 :(得分：3)
这是因为您为标题设置了最小尺寸 因此，当一个面板展开时，另一个面板会缩小，因为他的孩子（标题）允许它这样做。
不要为标题面板设置任何最小大小（在Netbeans IDE中，单击重置为默认值按钮）
问题应该消失。