集合讲解跟学习

package com.dongnao.lsn1

/**

 * Created by xiang on 2017/5/26.

 */

fun test(i: Int = 100, j: String = "") {

}

fun test(j: String = "") {

    val i = 100

}

//可变参数

fun test(vararg item: Int) {

    item.forEach { }

}

inline fun String.show() {

}

inline val String.lastChar: Char

    get() = get(length - 1)

fun main(args: Array<String>) {

    //list集合

    val list = listOf(1, 2, 3, 4)

    list[0]

    list.last()

    //遍历集合

    for (i in list) {

    }

    list.forEach {

        item ->

        println(item)

    }

    list.forEachIndexed { index, i -> }

    list.joinToString()

    //默认参数函数调用

    test()

    test(1)

    test(1, "11")

    test(j = "22")

    //可变长度参数

    test(1, 2, 3, 4, 5, 6, 7)

    //扩展方法

    "".show()

    //map映射集合

    val map = mapOf(1 to "a", 2 to "b", "c" to 1)

    //获取对应key元素

    map[1]

    map["c"]

    //中缀调用 infix

    1 to "a"

    1.to("a")

    //中缀方法

    1 with "a"

    //析构声明

    val pair = "a" to "b"

    val (key, value) = pair

    val compile = "com.android.support.constraint:constraint-layout:1.0.2"

    val (group, name, version) = compile.split(":")

}

infix fun <A, B> A.with(that: B): Pair<A, B> = Pair(this, that)

原文链接：http://www.apkbus.com/blog-340477-76708.html