JAVA程序测试之Swing编程

package swingtest;

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.*;

public class HelloApp extends JFrame{

    public static void main(String [] args)
    {

        SwingUtilities.invokeLater(new Runnable(){
            public void run(){
                HelloApp inst = new HelloApp();
                inst.setLocationRelativeTo(null);
                inst.setVisible(true);
            }
        }
                );

    }
    public HelloApp()
    {
        super();
        initGUI();
    }

    private void initGUI()
    {
        try
        {
            setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
            JMenuBar mbar = new JMenuBar();
            setJMenuBar(mbar);
            JMenu mfile = new JMenu();
            mbar.add(mfile);
            mfile.setText("File");
            JMenuItem showHello = new JMenuItem();
            mfile.add(showHello);
            showHello.setText("Hello");

            showHello.addActionListener(new ActionListener(){
                public void actionPerformed(ActionEvent e)
                {
                    JOptionPane.showMessageDialog(null,"Hello World","This is a message dialog",JOptionPane.DEFAULT_OPTION);
                }
            }
            );

            JMenuItem exitem = new JMenuItem();
            mfile.add(exitem);
            exitem.setText("Exit");

            pack();
            setSize(400,300);

            JToolBar toolBar = new JToolBar();
            getContentPane().add(toolBar,BorderLayout.SOUTH);
            JButton bInBar = new JButton();
            toolBar.add(bInBar);
            bInBar.setText("Say Hello");

            JTextField textf = new JTextField();
            getContentPane().add(textf,BorderLayout.NORTH);
            textf.setText("Please input the text");

        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
    }

}