Kotlin - 创建一个用于比较任何类型数字的函数

Question

我有下面的 Kotlin 对象声明，检测到气味(重复代码)

object Random {

    internal fun generatePositiveFloat(
        leftLimit: Float = Float.MIN_VALUE,
        rightLimit: Float = Float.MAX_VALUE
    ): Float {
        if (leftLimit < 0) {
            throw InvalidAlgorithmParameterException("
                Left limit can't be negative"
            )
        } else if (rightLimit <= leftLimit) {
            throw InvalidAlgorithmParameterException(
                "Right limit can't be less or equal than left limit"
            )
        }
        return Random().nextFloat()
     }

    internal fun generatePositiveShort(
        leftLimit: Short = 0,
        rightLimit:  Short = Short.MAX_VALUE
    ): Short {
        if (leftLimit < 0) {
            throw InvalidAlgorithmParameterException(
                "Left limit can't be negative"
            )
        } else if (rightLimit <= leftLimit) {
            throw InvalidAlgorithmParameterException(
                "Right limit can't be less or equal than left limit"
            )
        }
        return ThreadLocalRandom.current().nextInt(
            leftLimit.toInt(),
            rightLimit.toInt()
        ).toShort()
}

将这个重复的代码提取到私有(private)函数中的任何想法？

我的想法是这样的......

private fun validatePositiveLimits(
    leftLimit: Number,
    rightLimit: Comparable<Number>) {

    if (leftLimit as Comparable<Number> < 0) {
        throw InvalidAlgorithmParameterException(
            "Left limit can't be negative"
        )
    } else if (rightLimit <= leftLimit) {
        throw InvalidAlgorithmParameterException(
            "Right limit can't be less or equal than left limit"
        )
    }
}

...但我无法将 leftLimit 与 0 进行比较(leftLimit as Comparable < 0)。

我得到 ClassCastException 试图将整数转换为短整数并尝试将整数转换为浮点数。

非常感谢。

Answer 1

一些简单的泛型可以在这里提供解决方案:

private fun <T : Comparable<T>> checkConditions(left: T, right: T, leftLowerBound: T) {
    if (left < leftLowerBound) {
        throw InvalidAlgorithmParameterException(
            "Left limit can 't be negative"
        )
    } else if (right <= left) {
        throw InvalidAlgorithmParameterException(
            "Right limit can't be less or equal than left limit"
        )
    }
}

像这样为 Float 调用:

checkConditions(leftLimit, rightLimit, 0F)

就像这样的短:

checkConditions(leftLimit, rightLimit, 0.toShort())