- htafoya 是的,在 Kotlin 中,dog::class返回KClass<out Dog>,这意味着我们不能真正使用它来访问dog的任何成员。我相信原因是否则就可以:(dog as Animal)::class,然后使用它来访问Animal对象的Dog成员。但是,如果我们确定要使用完全相同的dog对象来获取KClass并使用其成员,我认为将KClass<out Dog>强制转换为K...
Lambda functions are anonymous functions which are usually created during a function call to act as a function parameter. They are declared by surrounding expressions with {braces} - if arguments are needed, these are put before an arrow ->. 代码语言:javascript 复制 {name:String->"Your name i...
简单的例子如下: valoriginal="abc"// Evolve the value and send to the next chainoriginal.let{println("The original String is $it")// "abc"it.reversed()// evolve it as parameter to send to next let}.let{println("The reverse String is $it")// "cba"it.length// can be evolve to ...
We have an array of integers. The array is filtered with thefilterfunction. It takes an anonymous function as a parameter. val filtered = vals.filter(fun(el) = el > 0) The anonymous function is used to filter the array. [1, 2, 3, 4] We have filtered out negative values. Kotlin c...
are those functions that take functions as a parameter and also returns a function. Consider the following code: fun alphaNum(func: () -> Unit) {} In the above code “func” is the name of the parameter and “ ( ) -> Unit ” is the function type. In this case, we are saying th...
2.Function References We can reference a function without actually calling it by prefixing the function's name with ::. This can then be passed to a function which accepts some other function as a parameter. funaddTwo(x:Int)=x+2listOf(1,2,3,4).map(::addTwo)#=>[3,4,5,6] ...
* Executes the given function [action] specified number of [times]. * * A zero-based index of current iteration is passed as a parameter to [action]. */ @kotlin.internal.InlineOnly public inline fun repeat(times: Int, action: (Int) -> Unit) { ...
Another experimental functioncapitalizehas been added on the JVM which takesLocaleobject as a parameter. You need to explicitly opt-in to use them: either annotate the use site with@UseExperimental(ExperimentalStdlibApi::class)or provide the compiler argument-Xuse-experimental=kotlin.ExperimentalStdlibAp...
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...
When you call a function with position-based arguments, the first argument corresponds to the first parameter, the second argument corresponds to the second parameter, and so on. So for passing a value for the 2nd parameter, you need to specify a value for the first parameter as well - ...