Kotlin扩展函数超详细介绍

//扩展String类的函数
fun String.addExtention() = "Kotlin: ".plus(this)
fun String.easyPrint() = println(this)
//扩展自定义类的函数
fun Apple.name() ="apple name "+this.name
//扩展泛型函数
fun <T> T.easyPrintln() {
    println(this)
}
//扩展属性计算字符串"a"的个数
val String.aCount
    get() = count { "a".contains(it) }
fun main() {
    val name = "HanMei"
    name.addExtention().easyPrint()
    val apple = Apple("apple")
    apple.name
    apple.easyPrintln()
    println(name.aCount)
}

val map = mapOf<Int,String>(1 to "hanmei")

public infix fun <A, B> A.to(that: B): Pair<A, B> = Pair(this, that)

package com.example.kotlin.gerneric
//扩展String类的函数
public fun String.addExtention() = "Kotlin: ".plus(this)

import com.example.kotlin.gerneric.addExtention
fun main() {
   val name = "HanMei".addExtention()
}

import com.example.kotlin.gerneric.addExtention as addEX
fun main() {
   val name = "HanMei".addEX()
}