JDialog大小无法改变

Question

用setSize（）也无法改变对话框的大小，为什么？

Answer 1

import javax.swing.*;
import javax.swing.border.*;
import java.awt.event.*;
import java.awt.List.*;
import java.awt.*;
public class AboutDialog extends JDialog implements ActionListener{
private JPanel jPanel=new JPanel();
JButton jButton=new JButton("OK");
private JLabel jLabel=new JLabel("作者:");
public AboutDialog(){
setTitle("123");
setResizable(true); Border  border1= BorderFactory.createCompoundBorder  (BorderFactory.createLineBorder (Color.green,2),BorderFactory.createEmptyBorder(2,10,2,10));
Border  border2=BorderFactory.createEtchedBorder(Color.pink,Color.blue); jLabel.setFont(new Font("宋体_GB2132",java.awt.Font.BOLD,18));
jButton.setBorder(border2);
jButton.setBackground(Color.lightGray);
jButton.setBounds(60,150, 30, 15);
jButton.addActionListener(this);
jButton.setBounds(new Rectangle(20,20,80,20));  
jPanel.setBorder(border1);
  jPanel.setLayout(null);
jPanel.add(jButton,null);  
jPanel.setLayout(new BorderLayout());
jPanel.add(jLabel,BorderLayout.NORTH);
jPanel.setBackground(Color.pink);
this.add(jPanel); Toolkit kit=Toolkit.getDefaultToolkit();
Dimension screenSize=kit.getScreenSize();
int ScreenHeight=screenSize.height;
int ScreenWidth=screenSize.width;
    setSize(600,800);
setLocation((ScreenWidth-this.getWidth())/2,(ScreenHeight-this.getHeight())/2);
setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE); pack();
this.setVisible(true);

  }
public void actionPerformed(ActionEvent e){
//System.exit(0);
this.dispose();
} 
public static void main(String[] args){
AboutDialog a=new AboutDialog();
}
}

Answer 2

pack()造成的，把pack()去掉再看看

Answer 3

用了pack()后，setSize也没有用了
JDK:pack（）调整此窗口的大小，以适合其子组件的首选大小和布局。