Kotlin扩展函数(also apply run let)和with函数

also apply run let with的使用例子

private fun testOperator() {/*** also*/val person = Person("ZhangSan", 18)person.also {// 通常仅仅打印使用, 也可以通过it修改it.name = "ZhangSan1"println("also inner name: " + it.name)}println("also name: ${person.name}")/*** apply*/person.apply {// 因为this的缘故, 访问成员变量更容易, 不需要使用"it."或者"this."increaseAge()name = "WangWu"println("apply inner age: $age")}println("apply name: ${person.name}")/*** run*/val person1 = Person("HeHe", 18)val person2 = person1.run {// run和let都会返回最后一个元素println("run inner name: $name")Person("Hello", 18)}println("run name: ${person1.name}")println("run name: ${person2.name}")/*** let* run可以完全替代let和with, let可以对空情况的统一处理*/var person3: Person? = Person("LiSi", 18)val flag = Random.nextInt(10)if (flag > 0) {person3 = null}person3.let {if (it == null) return@letit?.name = "LiSi1"println("let inner person3: $person3")}println("let person3: $person3")/*** with* with不是扩展函数, 属于标准库函数*/val person4: Person = Person("MaLiu", 18)val result = with(person4) {age = 24println("with inner age: $age")480}println("with result: $result")}class Person(var name: String, var age: Int) {fun increaseAge() {age += 1}fun changeName() {name = "YongLe"}}

扩展函数和with函数的特点概括