包含抽象方法的枚举类 学习笔记（二）

public enum Operation 
{
	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的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));
	}
}