我在获取顶部 JPanel（这本质上是最顶层的父 JPanel）的高度以调整其子 JPanel 的高度时遇到了一些问题。结果，当我将顶部 JPanel 放入网格布局时，父 JPanel 占用的子 JPanel 下方有额外的间隙。我想要做的是消除这个差距，这样顶部 JPanel 的大小将与子 JPanel 的大小相同。
本质上，父 JPanel 是一个扩展 JPanel 的类。我尝试使用子 JPanel 的大小将其调整为子 JPanel 的大小，但结果仍然相同。
this.setSize(childJPanel.getSize());
澄清一下，我使用 Matisse 可视化编辑器来编辑这个顶部 JPanel（设置为 GroupLayout），并且我将这个顶部 JPanel 放入另一个带有 GridLayout 的 JPanel 中。
如何强制顶部 JPanel 调整到其子 JPanel 的高度？
代码：
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package helloworld;
/**
*
* @author Justin
*/
public class FooPanel extends javax.swing.JPanel {
/**
* Creates new form NewJPanel
*/
public FooPanel() {
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() {
jPanel1 = new javax.swing.JPanel();
jLabel2 = new javax.swing.JLabel();
jPanel1.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 0, 0)));
jLabel2.setText("HELLOWORLD");
javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
jPanel1.setLayout(jPanel1Layout);
jPanel1Layout.setHorizontalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addContainerGap()
.addComponent(jLabel2)
.addContainerGap(122, Short.MAX_VALUE))
);
jPanel1Layout.setVerticalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addContainerGap()
.addComponent(jLabel2)
.addContainerGap(45, Short.MAX_VALUE))
);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(this);
this.setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
);
}// </editor-fold>
// Variables declaration - do not modify
private javax.swing.JLabel jLabel2;
private javax.swing.JPanel jPanel1;
// End of variables declaration
}
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package helloworld;
import java.awt.GridLayout;
import javax.swing.border.EmptyBorder;
/**
*
* @author Justin
*/
public class NewJApplet extends javax.swing.JApplet {
/**
* Initializes the applet NewJApplet
*/
@Override
public void init() {
/* 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(NewJApplet.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(NewJApplet.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(NewJApplet.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(NewJApplet.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/* Create and display the applet */
try {
java.awt.EventQueue.invokeAndWait(new Runnable() {
public void run() {
initComponents();
FooPanel panel1 = new FooPanel();
FooPanel panel2 = new FooPanel();
FooPanel panel3 = new FooPanel();
myPanel.setBorder(new EmptyBorder(5, 5, 5, 5) );
myPanel.setLayout(new GridLayout(0,1));
myPanel.add(panel1);
myPanel.add(panel2);
myPanel.add(panel3);
}
});
} catch (Exception ex) {
ex.printStackTrace();
}
}
/**
* This method is called from within the init() method 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() {
myPanel = new javax.swing.JPanel();
javax.swing.GroupLayout myPanelLayout = new javax.swing.GroupLayout(myPanel);
myPanel.setLayout(myPanelLayout);
myPanelLayout.setHorizontalGroup(
myPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 200, Short.MAX_VALUE)
);
myPanelLayout.setVerticalGroup(
myPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 300, Short.MAX_VALUE)
);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addComponent(myPanel, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(0, 200, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(myPanel, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
);
}// </editor-fold>
// Variables declaration - do not modify
private javax.swing.JPanel myPanel;
// End of variables declaration
}
结果：
