如何跨一组枚举类编写字符串到枚举值的可重用转换？（科特林）

Question

enum class Religiousness(val jsonStr: String, val resID: Int) {
    NotAtAll("none", R.string.not_religious),
    Somewhat("somewhat", R.string.somewhat_religious),
    Very("very", R.string.very_religious),
    ;
    override fun toString() = jsonStr
    fun displayString(res: Resources) = res.getString(resID)
}

fun JsonConvertStrToEnum(enumClass: Class<Enum<*>>, str: String): Enum<*> {
    for (enumval in enumClass.enumConstants) {
        if ((enumval as IJsonStringConvertible).jsonStr() == str)
            return enumval
    }
    throw IllegalArgumentException("Gave an invalid enum value for class ${enumClass.canonicalName}")
}

fun JsonConvertStrToEnum(enumClass: Class<out Enum<*>>, str: String): Enum<*> {
    for (enumval in enumClass.enumConstants) {
        if (enumval.toString() == str)
            return enumval
    }
    throw IllegalArgumentException("Gave an invalid enum value for class ${enumClass.canonicalName}")
}

Answer 1

枚举和其他类一样可以实现如下接口：

interface IJsonStringConvertible {
    val jsonStr:String
}

enum class Religiousness(override val jsonStr: String, val resID: Int) : IJsonStringConvertible {
    NotAtAll("none", R.string.not_religious),
    Somewhat("somewhat", R.string.somewhat_religious),
    Very("very", R.string.very_religious),
    ;

    override fun toString() = jsonStr
    fun displayString(res: Resources) = res.getString(resID)
}

然后将用作：

for (enumval in enumClass.enumConstants) {
    if ((enumval as IJsonStringConvertible).jsonStr == str)
        return enumval
}

但是，上面的查找可能很昂贵（如果使用数百万次）。看看反向查找问题，了解如何更有效地进行查找。