java实现四则运算switch

在Java中，可以使用`switch-case`语句实现简单的四则运算，但是由于Java不支持直接对数值类型做算术运算后的条件判断，通常我们会创建一个枚举或者利用if-else结构来完成这个任务。这里以一个基础的加法运算为例：

public enum Operation {
    ADD {
        @Override
        public int perform(int a, int b) {
            return a + b;
        }
    },
    SUBTRACT {
        @Override
        public int perform(int a, int b) {
            return a - b;
        }
    },
    MULTIPLY {
        @Override
        public int perform(int a, int b) {
            return a * b;
        }
    },
    DIVIDE {
        @Override
        public double perform(int a, int b) {
            if (b != 0) {
                return (double) a / b;
            } else {
                throw new ArithmeticException("Cannot divide by zero");
            }
        }
    };

    abstract public int perform(int a, int b);
}

// 使用示例
public static void main(String[] args) {
    int num1 = 5;
    int num2 = 3;
    Operation operation = Operation.ADD; // 可以根据需要切换操作

    switch (operation) {
        case ADD:
            System.out.println(num1 + " + " + num2 + " = " + operation.perform(num1, num2));
            break;
        case SUBTRACT:
            System.out.println(num1 + " - " + num2 + " = " + operation.perform(num1, num2));
            break;
        case MULTIPLY:
            System.out.println(num1 + " * " + num2 + " = " + operation.perform(num1, num2));
            break;
        case DIVIDE:
            System.out.println(num1 + " / " + num2 + " = " + operation.perform(num1, num2));
            break;
    }
}

在这个例子中，`Operation`枚举包含了四个成员，每个成员都有一个对应的`perform`方法来处理对应的运算。然后通过`switch`根据选择的`Operation`调用对应的方法。