java 枚举实现接口

public interface IOperation {
double apply(double x,double y);
}
enum BasicOperation implements IOperation{
PLUS("+"){
public double apply(double x,double y){return x+y;}
},
MINUS("-"){
public double apply(double x,double y){return x-y;}
},
TIMES("*"){
public double apply(double x,double y){return x*y;}
},
DIVIDE("/"){
public double apply(double x,double y){return x/y;}
};
private final String symbol;

BasicOperation(String symbol) {
this.symbol=symbol;
}

@Override
public String toString() {
return symbol;
}
}

enum ExtendedOpertation implements IOperation{
EXP("^"){
public double apply(double x,double y){return Math.pow(x, y);}
},
DIVIDE("%"){
public double apply(double x,double y){return x%y;}
};
private final String symbol;

ExtendedOpertation(String symbol) {
this.symbol=symbol;
}

@Override
public String toString() {
return symbol;
}
}