在 Kotlin 中,您可以通过为您的类型定义名为 isInstance 的函数来支持 is 运算符。例如: open class Animal class Cat : Animal() val animal = Cat() if (animal is Cat) { // 如果动物是一只猫,则执行以下操作 } 在这个示例中,Cat 类型是 Animal 类型的子类型。当您使用 is 运算符检查某个动物...
Using If as an Expression In Kotlin, You can use if as an expression instead of a statement. For example, you can assign the result of an if-else expression to a variable. Let’s rewrite the if-else example of finding the maximum of two numbers that we saw in the previous section as...
override operator fun equals(other: Any?): Boolean { if (other !is People) { return false } return this.userId == other.userId } } val userA = People("Coffee",12345) val userB = People("Coffeeee",12345) val userC = People("Coffee",54321) println("A跟B${if(userA == userB...
kt中的if与java的用法类似,可以说java怎么用,kt就可以怎么用,但kt有更多的用法,如kt的if是可以用返回值的,在if的代码块的最后一句,如果为一个值,那么他就是if的返回值,这里需要注意的是,如果需要其有返回值,那每一个if条件的代码块的最后一行都需要是有一个同类型的值,否则无返回值 null可空值 在kt中,...
classPoint(valx:Int,valy:Int){overridefunequals(obj:Any?):Boolean{if(obj===this)returntrue//1if(obj!isPoint)returnfalsereturnobj.x==x&&obj.y==y}}funmain(args:Array<String>){println(Point(10,20)==Point(10,20))println(Point(10,20)!=Point(5,5))//2println(null==Point(1,2))} ...
if (obj is String) { // `obj` 在该条件分支内自动转换成 `String` println(obj::class) //class java.lang.String result = obj.length println(result) } // 在离开类型检测分支后,`obj` 仍然是 `Any` 类型 println(obj::class) // class java.lang.Object ...
In Kotlin, if can be used as an expression. While using if as an expression, the else branch is mandatory to avoid compiler error.In addition, we can assign the result of the if-else expression to a variable:val number = -50 val result = if (number > 0) { "Positive number" } ...
Note:Unlike Java,if..elsecan be used as astatementor as anexpression(to assign a value to a variable) in Kotlin. See an example at the bottom of the page to better understand it. Kotlin if Useifto specify a block of code to be executed if a condition istrue. ...
if-else语句是控制程序流程的最基本的形式,其中else是可选的。 在Kotlin 中,if 是一个表达式,即它会返回一个值(跟Scala一样)。 代码示例: package com.easy.kotlin fun main(args: Array<String>) { println(max(1, 2)) } fun max(a: Int, b: Int): Int { ...
fun main() { var nickName = "leavesC" nickName = nickName.run { if (isNotEmpty()) { this } else { "" } } println(nickName) } 17.2、with with 函数并不是扩展函数,不过由于作用相近,此处就一起介绍了。with 函数的第一个参数是接受者对象 receiver,第二个参数是在 receiver 对象类型上定义...