swing窗体

package wo;import java.awt.*;import java.awt.event.*;import javax.swing.*;public class Ex4{/** * @param args */JFrame myframe;JLabel lab;JDialog sub;public Ex4(){myframe=new JFrame("JFrame演示窗口");lab=new JLabel("世界，你好");sub=new JDialog(myframe,"我是对话框",true);sub.getContentPane().setLayout(new FlowLayout());sub.getContentPane().add(lab);myframe.getContentPane().setLayout(new FlowLayout());//myframe.getContentPane().add(lab);myframe.setSize(300,300);myframe.setVisible(true);myframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);sub.setSize(200,200);sub.setVisible(true);}public static void main(String[] args) {// TODO Auto-generated method stubnew Ex4();}}