Up to this point, we’ve explored two methods of passing a function as a parameter to a higher-order function in Kotlin: employing a lambda or a function reference. As previously highlighted, functions are trea
本文简单谈下Kotlin中的函数,包括表达式函数体,命名参数,默认参数,顶层函数,扩展函数,局部函数,Lambda表达式,成员引用,with/apply函数等。从例子入手,从一般写法到使用特性进行简化,再到原理解析。 1.表达式函数体 通过下面这个简单的例子看下函数声明相关的概念,函数声明的关键字是fun,嗯,比JS的function还简单。 Kotli...
operator fun <T : Any, R> KFunction<R>.invoke(params: T): R 然后我们可以像这样将它与任何函数一起使用: (foo::doSomething)(myParams) 我不确定这是否是一个好主意,因为它比显式调用工具函数更令人困惑。 - broot 不错,我尝试过类似的东西,但是在泛型方面遇到了问题,我漏掉了 as KClass<T>。
For example, this is how to declare the main function. 代码语言:javascript 代码运行次数:0 运行 AI代码解释 fun main(args: Array<string>) { // code here } The main function must be present in each Kotlin program. It accepts an array of strings as parameter and returns nothing. If a fun...
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 ...
descriptor: (Lkotlin/jvm/functions/Function0;)V flags: ACC_PUBLIC, ACC_STATIC, ACC_FINAL Code: stack=2, locals=1, args_size=1 0: aload_0 1: ldc #10 // String callback 3: invokestatic #16 // Method kotlin/jvm/internal/Intrinsics.checkParameterIsNotNull:(Ljava/lang/Object;Ljava/lang...
java.lang.NullPointerException: Parameter specified as non-null is null: method kotlin.jvm.internal.Intrinsics.checkNotNullParameter, parameter bundle 为什么会出现这个问题呢? 因为基类Dialog是Java写的,而在其onCreate方法中 protected void onCreate(Bundle savedInstanceState) { } Bundle参数是可以为空值的...
>.mapAs(): TO {return TO::class.primaryConstructor!!.let {it.parameters.map { kParameter ->//如果接受null,则返回,否则抛出异常//this[kParameter.name] :从当前的 map 中寻找。如果找到了则就是拿到了 value,否则异常kParameter to (this[kParameter.name] ?: if (kParameter.type.isMarked...
* Represents an effect of a function invocation, * either directly observable, such as the function returning normally, * or a side-effect, such as the function's lambda parameter being called in place. * * The inheritors are used in [ContractBuilder] to describe the contract of a function...
{// The corresponding parameter in the supertype 'OnViewClickedListener'// is named 'viewId'.// This may cause problems when calling this function with named arguments.object:OnViewClickedListener{overridefunonViewClicked(@Suppress("PARAMETER_NAME_CHANGED_ON_OVERRIDE")id:Int){println("onView...