kotlin的for循环遍历

最新推荐文章于 2025-10-18 14:15:31 发布

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本文介绍了Kotlin中使用for循环遍历List的不同方法，包括常规遍历、指定类型遍历、通过indices、withIndex函数、以及各种范围操作如..、step、downTo和until。

kotlin的for循环遍历

1、List

    val list = listOf("A", "B", "C")

    for (item in list) {
        println(item)
    }

A
B
C

2、List的in

    val list = listOf("A", "B", "C")
    for (item: String in list) {
        println(item)
    }

A
B
C

3、list.indices

    val list = listOf("A", "B", "C")
    for (index in list.indices) {
        val str = "$index is ${list[index]}"
        println(str)
    }

0 is A
1 is B
2 is C

4、withIndex

    val list = listOf("A", "B", "C")

    // withIndex()
    for ((i, v) in list.withIndex()) {
        val str = "$i $v"
        println(str)
    }

0 A
1 B
2 C

5、m..n

    for (item in 1..5) {
        println(item)
    }

1
2
3
4
5

6、step

    for (item in 0..5 step 2) {
        println(item)
    }

0
2
4

7、downTo

    for (item in 5 downTo 1) {
        println(item)
    }

5
4
3
2
1

8、downTo - step

    for (item in 5 downTo 0 step 2) {
        println(item)
    }

5
3
1

9、util

    for (item in 0 until 5) {
        println(item)
    }

0
1
2
3
4