写给 Java 开发者的 Kotlin 教程 (13) - 最佳实践

发表于 更新于 分类于 ，

表达式

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fun getDefaultLocale2(deliveryArea: String) = when (deliveryArea.toLowerCase()) {
    "germany", "austria" -> Locale.GERMAN
    "usa", "great britain" -> Locale.ENGLISH
    "france" -> Locale.FRENCH
    else -> Locale.ENGLISH
}
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fun getDefaultLocale(deliveryArea: String): Locale {
    val deliverAreaLower = deliveryArea.toLowerCase()
    if (deliverAreaLower == "germany" || deliverAreaLower == "austria") {
        return Locale.GERMAN
    }
    if (deliverAreaLower == "usa" || deliverAreaLower == "great britain") {
        return Locale.ENGLISH
    }
    if (deliverAreaLower == "france") {
        return Locale.FRENCH
    }
    return Locale.ENGLISH
}

Try

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val json = """{"message":"HELLO"}"""
val message = try {
    JSONObject(json).getString("message")
} catch (ex: JSONException) {
    json
}

对象工具类

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fun String.countAmountOfX(): Int {
    return length - replace("x", "").length
}
"xFunxWithxKotlinx".countAmountOfX()
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object StringUtil {
    fun countAmountOfX(string: String): Int{
        return string.length - string.replace("x", "").length
    }
}
StringUtil.countAmountOfX("xFunxWithxKotlinx")

优先使用命名参数

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val config2 = SearchConfig2(
       root = "~/folder",
       term = "kotlin",
       recursive = true,
       followSymlinks = true
)
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val config = SearchConfig()
       .setRoot("~/folder")
       .setTerm("kotlin")
       .setRecursive(true)
       .setFollowSymlinks(true)
StringUtil.countAmountOfX("xFunxWithxKotlinx")

不要重载默认参数

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fun find(name: String, recursive: Boolean = true){
}
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fun find(name: String){
    find(name, true)
}
fun find(name: String, recursive: Boolean){
}

考虑使用 let

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findOrder()?.let { dun(it.customer) }
//or
findOrder()?.customer?.let(::dun)
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val order: Order? = findOrder()
if (order != null){
    dun(order.customer)
}