SpringLayout问题 新手求助
我是JAVA新手 在练习SpringLayout布局时 放在SpringLayout布局容中的控件不会显示 找不出问题 请高手帮忙 小弟在此谢过
下面是我写的程序
package buju.tanhuang;
import javax.swing.*;
public class Lianxi extends JFrame
{
/**
* @param args
*/
private JButton j1=new JButton("弹簧布局");
private JPanel jpa=new JPanel();
private SpringLayout ss1=new SpringLayout();
public Lianxi()
{
jpa.setLayout(ss1);
jpa.add(j1);
Spring a1=Spring.constant(0,100,400);
ss1.putConstraint(SpringLayout.WEST,j1,20,SpringLayout.WEST,jpa);
ss1.putConstraint(SpringLayout.EAST,j1,20,SpringLayout.EAST,jpa);
ss1.putConstraint(SpringLayout.NORTH,j1,20,SpringLayout.NORTH,jpa);
ss1.putConstraint(SpringLayout.WEST, j1, a1, SpringLayout.EAST, j1);
//jpa.revalidate();
this.add(jpa);
this.setTitle("弹簧布局练习");
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
this.setBounds(200, 200, 200, 100);
this.setVisible(true);
}
public static void main(String[] args)
{
// TODO Auto-generated method stub
new Lianxi();
}
}