/** * 时钟类 *  * @author Administrator *  */public class Clock {	private int hour;	private int minute;	private int second;	public Clock() {		Calendar cal =  Calendar.getInstance();		this.hour = cal.get(Calendar.HOUR_OF_DAY);		this.minute = cal.get(Calendar.MINUTE);		this.second = cal.get(Calendar.SECOND);	}		public Clock(int hour, int min, int sec) {		this.hour = hour;		this.minute = min;		this.second = sec;	}	public void goon() {		second++;		if (second == 60) {			second = 0;			minute++;			if (minute == 60) {				minute = 0;				hour++;				if (hour == 24) {					hour = 0;				}			}		}	}			public boolean countDown(){		if(second >= 0){			second--;			if(second<=0){				second=59;				minute--;				if(minute < 0){					minute = 59;					hour--;					if(hour < 0){						hour = 0;					}				}			}		}		return hour == 0 && minute == 0 && second == 0;	}	public String toString() {		DecimalFormat df = new DecimalFormat("00");		return df.format(hour) + ":" + df.format(minute) + ":"				+ df.format(second);	}}public class ClockGUI {		private static Timer timer = null;		public static void main(String[] args) throws Exception {		final Clock sj = new Clock(1, 1, 2);		JFrame w = new JFrame();		w.setVisible(true);		w.setSize(800, 600);		w.setTitle("时钟");		w.setResizable(false);		w.setLocationRelativeTo(null);		w.setLayout(null);		w.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);		JLabel lbl1 = new JLabel("剩余时间：");		Font font = new Font("楷体", 1, 56);		lbl1.setFont(font);		lbl1.setBounds(50, 200, 700, 120);		w.add(lbl1);		final JLabel lbl2 = new JLabel("");		Font font1 = new Font("楷体", 1, 56);		lbl2.setFont(font1);		lbl2.setBounds(320, 200, 700, 120);		lbl2.setText(sj.toString());		w.add(lbl2);		timer = new Timer(1000, new ActionListener() {						@Override			public void actionPerformed(ActionEvent e) {				if(sj.countDown()) {					timer.stop();					JOptionPane.showMessageDialog(null,"时间结束！");				}				lbl2.setText(sj.toString());			}		});		timer.start();	}}

/** * 分数类 *  * @author Administrator *  */public class Rational {	/** 分子 */	private int num;	/** 分母 */	private int den;	public Rational(int num, int den) {		this.num = num;				this.den = den;		normalize();	}		public Rational(String str){		String s1 = str.split("/")[0];		String s2 = str.split("/")[1];				this.num = Integer.parseInt(s1);		this.num = Integer.parseInt(s2);		normalize();	}	//	public Rational()		/**	 * 分数加法	 * 	 * @param other	 * @return	 */	public Rational add(Rational other) {		return new Rational(this.num * other.den + this.den * other.num,				this.den * other.num).normalize();	}	/**	 * 分数减法	 * 	 * @param other	 * @return	 */	public Rational sub(Rational other) {		return new Rational(this.num * other.den - this.den * other.num,				this.den * other.num).normalize();	}	/**	 * 分数乘法	 * 	 * @param other	 * @return	 */	public Rational mul(Rational other) {		return new Rational(this.num * other.num, this.den * other.den).normalize();	}	/**	 * 分数除法	 * 	 * @param other	 * @return	 */	public Rational div(Rational other) {		return new Rational(this.num * other.den, this.den * other.num).normalize();	}	/**	 * 化简	 * 	 * @return 化简后的分数对象	 */	public Rational simplify() {		int divisor = gcd(Math.abs(num), Math.abs(den));		num /= divisor;		den /= divisor;		return this;	}	/**	 * 正规化	 * @return 正规化以后的分数对象	 */	public Rational normalize(){		if(this.num == 0){			this.den=1;		}else if(this.den<0){			this.den = -this.den;			this.num = -this.num;		}		return this;	}			public String toString() {		return num + (den != 1 ? ("/" + den) : "");	}	/**	 * 找分子和分母的最大公约数	 * 	 * @param x	 * @param y	 * @return	 */	private int gcd(int x, int y) {		if (x > y) {			return gcd(y, x);		}		for (int i = x; i > 1; i--) {			if (x % i == 0 && y % i == 0) {				return i;			}		}		return 1;	}}