import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.*;
class JButtonDemo extends JFrame implements ActionListener
{
	JButton button1,button2,button3;
	JLabel label;
	JButtonDemo()
	{
		super("按鈕動作范例");
		label=new JLabel("歡迎進入Java世界！",JLabel.CENTER);
		button1=new JButton("日期[d]");
		button1.setMnemonic('d');           //設置快捷鍵為d
		button1.setActionCommand("date");   //設置動作命令為welcome
		button1.addActionListener(this);    //注冊事件監聽器
        button2=new JButton("時間[t]");
		button2.setMnemonic('t');           //設置快捷鍵為t
		button2.setActionCommand("time");   //設置動作命令為date	
		button2.addActionListener(this);    //注冊事件監聽器
		button3=new JButton("退出[q]");
		button3.setMnemonic('q');           //設置快捷鍵為q
		button3.setActionCommand("quit");   //設置動作命令為quit
		button3.addActionListener(this);    //注冊事件監聽器
		getContentPane().add(label,BorderLayout.NORTH);
		getContentPane().add(button1,BorderLayout.WEST);
		getContentPane().add(button2,BorderLayout.CENTER);
		getContentPane().add(button3,BorderLayout.EAST);
    }
    public void actionPerformed(ActionEvent e)
    {
    	Calendar c=Calendar.getInstance();  //得到系統日歷類的對象  
    	if(e.getActionCommand().equals("date"))
    	{
    	    label.setText("今天是"+c.get(Calendar.YEAR)+"年"+c.get(Calendar.MONTH)+"月"+c.get(Calendar.DATE)+"日");
    	    label.setHorizontalAlignment(JLabel.LEFT);//設置標簽的文本左對齊
    	}
    	else if(e.getActionCommand().equals("time"))
    	{
    	    label.setText("現在是"+c.get(Calendar.HOUR)+"時"+c.get(Calendar.MINUTE)+"分"+c.get(Calendar.SECOND)+"秒");
    	    label.setHorizontalAlignment(JLabel.RIGHT);//設置標簽的文本右對齊
        }
    	else System.exit(0);
    }
	public static void main(String args[])
	{
		
		JFrame frame=new JButtonDemo();
    	frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    	frame.pack();
    	frame.setVisible(true);
	}
}