如何修复operation switch语句

Question

在这个名为AClass的类中，我尝试了使用输入在两个值之间的运算符的switch语句。

public interface Operation {
  public enum Operator {Add, Sub, Mult, Div, Rem}
}


import java.util.*;
import java.io.*;

public class AClass<I> implements Operation {

    AClass <Integer> leftoperand = new AClass <Integer>();
    AClass <Operator> operation = new AClass <Operator>();
    AClass <Integer> rightoperand = new AClass <Integer>(); 

  public Integer value (SClass sc) {
    switch (operation) {
        case Add:
            return leftoperand.value(sc) + rightoperand.value(sc);
        case Sub:
            return leftoperand.value(sc) - rightoperand.value(sc);
        case Mult:
            return leftoperand.value(sc) * rightoperand.value(sc);
        case Div:
            return leftoperand.value(sc) / rightoperand.value(sc);
        case Rem:
            return leftoperand.value(sc) % rightoperand.value(sc);
    }
  }

  public String toString() {
   return "(" + leftoperand + "," + operation + "," + rightoperand + ")";
  }
}
Error: incompatible types: AClass<AClass.Operator> cannot be converted to int

Error: cannot find symbol
  symbol:   variable Add
  location: class AClass<I>

Error: cannot find symbol
  symbol:   variable Sub
  location: class AClass<I>

Error: cannot find symbol
  symbol:   variable Mult
  location: class AClass<I>

Error: cannot find symbol
  symbol:   variable Div
  location: class AClass<I>

Error: cannot find symbol
  symbol:   variable Rem
  location: class AClass<I>

我收到了一些错误，从switch (操作)行开始。我该如何着手解决这个问题呢？另外，我是否可以直接在AClass中插入枚举操作符，而不是使用接口？

Answer 1

Java switch语句并不支持所有类。在java文档中，与if-then和if-then-else语句不同，switch语句可以有许多可能的执行路径。开关使用byte、short、char和int基元数据类型。它还适用于枚举类型(在枚举类型中讨论)、String类和一些包装某些基元类型的特殊类: Character、Byte、Short和Integer (在数字和字符串中讨论)。

AClass <Operator> operation = new AClass <Operator>(); // will not work
Operator operation = Operator.ADD; // will work since operator is an enum;