Kotlin基本语法（二）

来源：互联网发布：琼斯镇惨案知乎编辑：程序博客网时间：2024/05/17 22:16

9、使用ranges

使用 in 操作符检查数值是否在某个范围内：fun main(args: Array<String>) {  val x = 10  val y = 9  if (x in 1..y+1) {  println("fits in range")  }}

检查数值是否在范围外：fun main(args: Array<String>) {  val list = listOf("a", "b", "c")  if (-1 !in 0..list.lastIndex) {  println("-1 is out of range")} if (list.size !in list.indices) {  println("list size is out of valid list indices range too") }}

在范围内迭代fun main(args: Array<String>) {  for (x in 1..5) {   print(x)  }}

或者使用步进：fun main(args: Array<String>) {  for (x in 1..10 step 2) {   print(x)  }  for (x in 9 downTo 0 step 3) {   print(x)  }}

10、使用集合

对一个集合进行迭代：fun main(args: Array<String>) {  val items = listOf("apple", "banana", "kiwi")  for (item in items) {  println(item)  }}

使用 in 操作符检查集合中是否包含某个对象fun main(args: Array<String>) {  val items = setOf("apple", "banana", "kiwi")  when {   "orange" in items -> println("juicy")   "apple" in items -> println("apple is fine too")  }}

使用lambda表达式过滤和映射集合：fun main(args: Array<String>) {  val fruits = listOf("banana", "avocado", "apple", "kiwi")  fruits   .filter { it.startsWith("a") }   .sortedBy { it }   .map { it.toUpperCase() }   .forEach { println(it) }}

阅读全文

0 0