/
KotlinTip3.kt
71 lines (62 loc) · 1.91 KB
/
KotlinTip3.kt
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package com.sw.kotlin.tip3
fun printList() {
val list = listOf(2, 4, 0)
println(list)
}
/*
* 打印列表的内容
* */
fun <T> joinToString(collection: Collection<T>,
separator: String,
prefix: String,
postfix: String): String {
val result = StringBuilder(prefix)
for ((index, element) in collection.withIndex()) {
if (index > 0) result.append(separator)
result.append(element)
}
result.append(postfix)
return result.toString()
}
fun printList2() {
val list = listOf(2, 4, 0)
/*不标明参数名*/
println(joinToString(list, " - ", "[", "]"))
/*显示的标明参数名称*/
println(joinToString(list, separator = " - ", prefix = "[", postfix = "]"))
}
/*
* 打印列表的内容,带有默认的参数,可以避免java的函数重载
* */
fun <T> joinToString2(collection: Collection<T>,
separator: String = ", ",
prefix: String = "",
postfix: String = ""): String {
val result = StringBuilder(prefix)
for ((index, element) in collection.withIndex()) {
if (index > 0) result.append(separator)
result.append(element)
}
result.append(postfix)
return result.toString()
}
fun printList3() {
val list = listOf(2, 4, 0)
println(joinToString2(list, " - "))
}
/*
* 通过注解@JvmOverloads解决java调用kotlin时不支持默认参数的问题
* */
@JvmOverloads
fun <T> joinToString2New(collection: Collection<T>,
separator: String = ", ",
prefix: String = "",
postfix: String = ""): String {
val result = StringBuilder(prefix)
for ((index, element) in collection.withIndex()) {
if (index > 0) result.append(separator)
result.append(element)
}
result.append(postfix)
return result.toString()
}