import java.awt.*;
import java.awt.event.*;
import java.applet.*;

class SeparateSubTask extends Thread {
	private int count = 0;
	private Counter2 c2;
	private boolean runFlag = true;
	public SeparateSubTask(Counter2 c2) {
		this.c2 = c2;
		start();
	}
	public void invertFlag() { if(runFlag) runFlag = !runFlag;}
	public void run() {
		while (true) {
			try {
				sleep(100);
			} catch (InterruptedException e){}
			if(runFlag) 
				c2.t.setText(Integer.toString(count++));
		}
	}
} 

public class Counter2 extends Applet {
	TextField t = new TextField(10);
	private SeparateSubTask sp = null;
	private Button 
    	onOff = new Button("停止計數"),
    	start = new Button("開始計數");
	public void init() {
		add(t);
		start.addActionListener(new StartL());
		add(start);
		onOff.addActionListener(new OnOffL());
		add(onOff);
	}
	class StartL implements ActionListener {
		public void actionPerformed(ActionEvent e) {
			if(sp == null)
				sp = new SeparateSubTask(Counter2.this);
		}
	}
	class OnOffL implements ActionListener {
		public void actionPerformed(ActionEvent e) {
			if(sp != null)
				sp.invertFlag();
		}
	}
	public static void main(String[] args) {
		Counter2 applet = new Counter2();
		Frame aFrame = new Frame("計數器");
		aFrame.addWindowListener(
				new WindowAdapter() {
					public void windowClosing(WindowEvent e) {
						System.exit(0);
					}
				});
		aFrame.add(applet, BorderLayout.CENTER);
		aFrame.setSize(300,200);
		applet.init();
		applet.start();
		aFrame.setVisible(true);
	}
}