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What this article shares with you is about what Kotlin control flow refers to. The editor thinks it is very practical, so I share it with you to learn. I hope you can get something after reading this article.

The control flow in Kotlin is used for process control expressions such as if, when, for, while

If expression

In Kotlin, if is an expression that returns a value. It can be used to replace the ternary operator (condition? Then: otherwise)

If

Var a = 1var b = 2var max = aif (b > a) max = b println (max) / / 2

If else

Var min: Intif (a)

< b){ min = a}else{ min = b}println(min) //1 if作为表达式使用 var max2 = if(a >

B) an else bprintln (max2) / / 2

The branch of if can be a code block, with the final expression as the return value

Var max3 = if (a > b) {println ("a > b") a} else {println ("a")

< b") b}println(max3) //2 注意如果if作为表达式则必须有else分支 if的一些习惯用法 //if not nullvar str1: String? = "Hello Kotlin!" //?表示该类型可为nullprintln(str1?.length) //当str1变量不为null时访问length属性//if not null and elsevar str2: String? = "str"println(str2?.length ?: "null") //当str2变量不为null时访问length属性，否则返回"null"//if null执行一条语句var str3: String? = nullstr3?:println("str3 is null") //当str3变量为null时执行//if not null执行一段代码var str4: String = "111"str4?.let { //当str4变量不为null时执行{}里面的语句 println("str4 is not null") println("$str4.length is ${str4.length}")} when表达式 when表达式取代了switch，最简洁的语法如下 var x = 1when(x){ 1 ->

Println ("x = 1") 2-> println ("x = 2") else-> println ("x is nether 1 or 2")}

Multiple matching values are processed in the same way

When (x) {1,2-> println ("x = 1 or x = 2") else-> println ("otherwise")}

Make interval judgment

Var num = 10when (num) {in 1.. 10-> println ("num is between 1 and 10")! in 1.. 10-> println ("num is not between 1 and 10") else-> println ("num is out of range")}

Use when instead of if

Var a = 1var b = 2when {a > b-> println (a) a

< b ->

Println (b)}

When is used as an expression

Var str: Any = "" var type = when (str) {is Int-> "int" is String-> "String" else-> "other"} println (type) / / String

Note that when as an expression must have an else branch

For cycle

The for loop can traverse any object that provides an iterator, which is equivalent to foreach in other languages

Ergodic range

For (I in 1.. 10) {println (I) / / 1, 2, 4, 5, 6, 7, 8, 9, 10}

Until half-open interval, which does not include 10

For (I in 1 until 10) {println (I) / / 1 println (I) / / 1 until 2, 4, 5, 6, 7, 8, 9}

Specify the amount of growth for traversal

For (I in 1.. 10 step 2) {println (I) / / 1 step 3, 5, 7, 9}

Ergodic array

Var strs: Array = arrayOf ("one", "two", "three") for (str in strs) {println (str)}

The for loop on the array is compiled into an index-based loop that does not create an iterator. The following figure shows the decompiled result of the above code

If you want to use indices through index traversal

For (I in strs.indices) {println (strs [I])}

Or use the withIndex function

For ((index, value) in strs.withIndex ()) {println ("the element at $index is $value")}

Using break and continue in loops

For (I in 1.. 10) {if (I > = 5) break / / Jump out of the current cycle if (I% 2! = 0) continue / / end this cycle and proceed to the next cycle println (I) / / print: 2Quin4}

While cycle and do while cycle

Like most languages, there is no change in these two cycles.

While cycle

Var I: Int = 10while (I > 0) {println (I) imuri -}

Do while cycle

Var a: Int = 10do {println (a) a println -} while (a > 0) the above is what Kotlin control flow refers to. The editor believes that there are some knowledge points that we may see or use in our daily work. I hope you can learn more from this article. For more details, please follow the industry information channel.

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