是否可以将算术运算符传递给java中的方法？ [英] Is it possible to pass arithmetic operators to a method in java?

问题描述

现在我将不得不编写一个如下所示的方法：

Right now I'm going to have to write a method that looks like this:

public String Calculate(String operator, double operand1, double operand2)
{

        if (operator.equals("+"))
        {
            return String.valueOf(operand1 + operand2);
        }
        else if (operator.equals("-"))
        {
            return String.valueOf(operand1 - operand2);
        }
        else if (operator.equals("*"))
        {
            return String.valueOf(operand1 * operand2);
        }
        else
        {
            return "error...";
        }
}

如果我能编写更多代码，那就太好了像这样：

It would be nice if I could write the code more like this:

public String Calculate(String Operator, Double Operand1, Double Operand2)
{
       return String.valueOf(Operand1 Operator Operand2);
}

因此运算符将替换算术运算符（+， - ，*，/。 ..）

So Operator would replace the Arithmetic Operators (+, -, *, /...)

有没有人知道这样的东西在java中是否可行？

Does anyone know if something like this is possible in java?

推荐答案

不，你不能用Java做到这一点。编译器需要知道运算符正在做什么。您可以做的是enum：

No, you can't do that in Java. The compiler needs to know what your operator is doing. What you could do instead is an enum:

public enum Operator
{
    ADDITION("+") {
        @Override public double apply(double x1, double x2) {
            return x1 + x2;
        }
    },
    SUBTRACTION("-") {
        @Override public double apply(double x1, double x2) {
            return x1 - x2;
        }
    };
    // You'd include other operators too...

    private final String text;

    private Operator(String text) {
        this.text = text;
    }

    // Yes, enums *can* have abstract methods. This code compiles...
    public abstract double apply(double x1, double x2);

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

然后您可以编写如下方法：

You can then write a method like this:

public String calculate(Operator op, double x1, double x2)
{
    return String.valueOf(op.apply(x1, x2));
}

并将其称为：

String foo = calculate(Operator.ADDITION, 3.5, 2);
// Or just
String bar = String.valueOf(Operator.ADDITION.apply(3.5, 2));

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