枚举类+抽象方法+内部类

package Class_study;

public enum Operation {//枚举类+内部类+抽象函数
    Divide{
        public double eval(double x,double y){
            return x/y;
        }
    },Pluse{
        public double eval(double x,double y){
            return x-y;
        }

    },Add{
        public double eval(double x,double y){
            return x+y;
        }
    },Minus{
        public double eval(double x,double y){
            return x*y;
        }
    };
    abstract public double eval(double x ,double y);
    public static void main(String args[]){
        System.out.println(Operation.Add.eval(2, 7));
        System.out.println(Operation.Add.eval(8, 8));
    }

}

每个枚举对象对应自己的方法