枚舉類+抽象方法+內部類

package Class_study;

public enum Operation {//枚舉類+內部類+抽象函數
    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));
    }
    

}

每一個枚舉對象對應本身的方法