Example 2: Check if a string is numeric or not using regular expressions (regex) fun main(args: Array<String>) { val string = "-1234.15" var numeric = true numeric = string.matches("-?\\d+(\\.\\d+)?".toRegex()) if (numeric) println("$string is a number") else println("$...
One way to check if a string is numeric is to parse it as a Double or Int (or other built-in numeric types). In case this parsing attempt doesn’t return null, we can safely assume that a String is a number: fun isNumericToX(toCheck: String): Boolean { return toCheck.toDoubleOr...
//sampleStart typealias OscarWinners = Map<String, String> fun countLaLaLand(oscarWinners: OscarWinners) = oscarWinners.count { it.value.contains("La La Land") } // 请注意,类型名称(初始名和类型别名)是可互换的: fun checkLaLaLandIsTheBestMovie(oscarWinners: Map<String, String>) = oscarWinne...
在Java中,复合按钮CompoundButton的勾选状态有两个,setChecked和isChecked,前者用于设置是否勾选,后者用于判断是否勾选,但在Kotlin中这两个方法被统一成了isChecked属性,修改isChecked的属性即为设置是否勾选,而获取isChecked的属性值即为判断是否勾选,这种合二为一的情况还有一些,如下表: 下面来使用一下这个CheckBox:...
public final User copy(long id, @NotNull String name, long signTime) { Intrinsics.checkParameterIsNotNull(name, "name"); return new User(id, name, signTime); } @NotNull public String toString() { return "User(id=" + this.id + ", name=" + this.name + ", signTime=" + this....
importcom.jetbrains.demo1funmain(args:Array<String>){demo1()} 然后运行次程序您会看到控制台输出 demo1 kotlin会默认导入一些包,这些包您无需在上方通过import手动导入 kotlin.* kotlin.annotation.* kotlin.collections.* kotlin.comparisons.*
In this tutorial, we’ll explore how to effectively check if a number is positive or negative in Kotlin. Further, we’ll build step by step an idiomatic function that works for allNumberinstances. 2. Introduction to the Problem Determining whether an integer is positive or negative isn’t a...
ERROR: Cannot checkforinstance of erasedtype 因为类型擦除的原因,导致运行时候不能确认它是一个String的List. Kotlin不允许使用没有指定类型参数的泛型。那我们怎么去检查一个对象是否是一个List呢,这里可以用星投射<*>, 例如 if(valueisList<*>) {...} ...
android kotlin 判断 any 是否为 String kotlin类型推断 基本类型 https:///huanglizhuo/kotlin-in-chinese/blob/master/Basics/Basic-Types.md 在Kotlin 中,所有变量的成员方法和属性都是一个对象。一些类型是内建的,它们的实现是优化过的,但对用户来说它们就像普通的类一样。在这节中,我们将会讲到大多数的类型...
@Composable fun MainScreen() { val map = remember { createMap() } Scaffold( topBar = { TopAppBar(title = { Text(text = stringResource(id = R.string.app_name)) }) } ) { MapView( modifier = Modifier.fillMaxSize().padding(it), arcGISMap = map ) } } fun createMap(): ArcGISMa...