作用域函数(scope functions).在kotlin.Standard.kt中。 用法1 fun main() { val numbers = mutableListOf("one", "two", "three", "four", "five") numbers.map { it.length }.filter { it > 3 }.let { println(it) // and more function calls if needed } } ...
Let function is another way to solve null problem in kotlin. When you have such problem: var favoriteColor: String? = null ... ... returniff(avoriteColor !==null) getLastLetter(favoriteColor)else"" The problem is 'favoriteColor' might change, so smart casting is complaining about this....
InvocationKind.EXACTLY_ONCE)4}5block()6returnthis7}89/**10* Calls the specified function [block] with `this` value as its argument and returns `this` value.11*12* For detailed usage information see the documentation for [scope functions](https://kotlinlang.org/docs/reference/scope-...
如果未提及返回值,则仅返回Kotlin.Unit。 funmain(){varstr ="Hello"// let function returning stringvartemp1 = str.let {vargm ="Good Morning""$it!$gm".toUpperCase()}// let function performing println function inside itvartemp2 = str.let{ greetings->for(iin1..3){println(greetings+"$i")...
1 普通函数 VS 扩展函数 (Normal vs. extension function) 如果我们对比 with 和T.run 这两个函数的话,他们实际上是十分相似的。下面使用他们实现相同的功能的例子. with(webview.settings) { javaScriptEnabled = true databaseEnabled = true } // similarly webview.settings.run { javaScriptEnabled = true...
kotlin function: run with let also apply Scoping functions (作用域 函数) 提供了一个 内部独立的区间(也就是方法的上下文 如下的run方法) run{} 提供独立上下文 with(T){} 上下文为参数 T.run{} 对比with(T) T.run{}是个拓展方法 extension function,默认参数是T. 就是T相当于方法内部(作用域内)的...
*/@kotlin.internal.InlineOnlypublicinlinefun<T>T.apply(block:T.()->Unit):T{contract{callsInPlace(block,InvocationKind.EXACTLY_ONCE)}block()returnthis} 1 2 3 4 5 6 7 8 9 10 11 12 13 而let的源码是 /** * Calls the specified function [block] with `this` value as its argument and...
Kotlin】类的继承 ① ( 使用 open 关键字开启类的继承 | 使用 open 关键字开启方法重写 )【Kotlin】...
let函数可能返回也可能不返回任何值。如果未提及返回值,则仅返回Kotlin.Unit。 funmain(){varstr ="Hello"// let function returning stringvartemp1 = str.let {vargm ="Good Morning""$it!$gm".toUpperCase()}// let function performing println function inside itvartemp2 = str.let{ greetings->for(i...
Kotlin run expression can change the outer property. Hence in the above code, we’ve redefined it for the local scope. Similar to the let function, the run function also returns the last statement. Unlike let, the run function doesn’t support theitkeyword. ...