循环 for/while
for-in/while/do-while、break/continue、标签跳转
循环 for/while
Kotlin 的 for 循环直接遍历任何可迭代对象——不需要手动管理索引。
学完本章你将： 掌握 for-in/while/do-while、break/continue、标签。
for-in 遍历
kotlin
// 遍历列表
val items = listOf("A", "B", "C")
for (item in items) {
println(item)
}
// 带索引
for ((index, item) in items.withIndex()) {
println("$index: $item")
}
// 遍历 Map
val map = mapOf("a" to 1, "b" to 2)
for ((key, value) in map) {
println("$key -> $value")
}while / do-while
kotlin
var i = 0
while (i < 5) {
println(i)
i++
}
var j = 0
do {
println(j)
j++
} while (j < 5)break 与 continue
kotlin
for (i in 1..10) {
if (i == 3) continue // 跳过
if (i == 8) break // 终止
println(i)
}标签跳转
kotlin
outer@ for (i in 1..3) {
for (j in 1..3) {
if (j == 2) break@outer // 跳出外层循环
println("$i, $j")
}
}