operation2.java

疯狂Java讲义_源码(含Java设计模式CHM

/**
 * Description:
 * <br/>Copyright (C), 2005-2008, Yeeku.H.Lee
 * <br/>This program is protected by copyright laws.
 * <br/>Program Name:
 * <br/>Date:
 * @author  Yeeku.H.Lee [e-mail]
 * @version  1.0
 */
public enum Operation2
{
	PLUS
	{
		public double eval(double x , double y)
		{
			return x + y;
		}
	}, 
	MINUS
	{
		public double eval(double x , double y)
		{
			return x - y;
		}
	}, 
	TIMES
	{
		public double eval(double x , double y)
		{
			return x * y;
		}
	}, 
	DIVIDE
	{
		public double eval(double x , double y)
		{
			return x / y;
		}
	};
	//为枚举类定义一个抽象方法，这个抽象方法由不同枚举值提供不同的实现
	public abstract double eval(double x, double y);
	public static void main(String[] args)
	{
		System.out.println(Operation.PLUS.eval(3, 4));
		System.out.println(Operation.MINUS.eval(5, 4));
		System.out.println(Operation.TIMES.eval(5, 4));
		System.out.println(Operation.DIVIDE.eval(5, 4));
	}
}