內(nèi)聯(lián)函數(shù)let with run apply also

//閉包形式返回
    //let定義一下作用域，判空處理
    haha.let {
        haha.run()
    }
    //類多個(gè)方法或?qū)傩?，防止類多?，多用于onBinderViewHolder中
    with(HaHa("vv",30)){
        println("$name$age")
    }
    //let+with屬性,返回最后一句話
    HaHa("vv",30).run {
        println("$name$age")
    }
    //返回this
    //let+with屬性，返回對(duì)象自身，用于實(shí)例初始化或 view = View.inflate().apply{初始化}
    val haHa = HaHa("vv",30).apply {
        println("$name$age")
    }
    //also 與let一樣，不過(guò)返回的是對(duì)象本身
    val haHa2 = HaHa("vv",30).also {
        println("$it.name$it.age")
    }

靜態(tài)常量

companion object{
    val foo:String = "aa"
    const val foo2:String = "bb"
    @JvmField
    val foo3 = "cc"
}

頂級(jí)常量：const val FOO = "foo"

集合數(shù)組常用操作

image.png

循環(huán)跳出

image.png

類型強(qiáng)轉(zhuǎn)

image.png

類基礎(chǔ)

//構(gòu)造函數(shù)
//無(wú)（注釋，可見性修飾符）constructor可省略
class SuperClass @JvmOverloads private constructor(name:String, age:Int = 0){}
class SuperClass1(name:String){
//    var j = SuperClass("jj")//JvmOverloads自動(dòng)生成2個(gè)構(gòu)造函數(shù)
}
//定義成員變量，演變1
class SuperClass2 (name:String,age:Int){
    private var name:String
    private var age:Int
    init {
        this.name = name
        this.age = age
    }
}
//演變2
class SuperClass3 (name:String,age:Int){
    private var name:String = name
    private var age:Int = age
}
//演變3
open class SuperClass4 (private var name: String, private var age: Int){
    constructor(name: String,age: Int,url:String):this(name,age){
    }
    constructor(name: String,age: Int,url:String,sex:Boolean):this(name,age,url){
    }
    //默認(rèn)類中所有是final的，想覆寫或繼承必須open
    open fun haHa(){
        this.name = "你好"http://this關(guān)鍵字用于訪問(wèn)對(duì)象的其他成員
        this.age = 90
    }
    fun hh(){}
}

class ChildClass constructor(private var name: String,private var age: Int,private var url: String) : SuperClass4(name,age,url,true){
    override fun haHa() {
        super.haHa()
        super.hh()
        this.url = "http://www.baidu.com"
    }
}
//抽象類的abstract修飾符默認(rèn)是open的
abstract class A{
    abstract fun jj()
    fun ii(i:Int){}
}

class B(private var age:Int) : A(){
    override fun jj() {
        super.ii(age)
    }
}
//接口
interface C{
    fun c()
}
interface D{
    fun d()
}
class E(food:String):C,D{
    override fun c() {}
    override fun d() {}
}
//嵌套類，內(nèi)部類
class Outer{
    var name = "sdfa"
    var jj = Nested().exe()
    class Nested{
        fun exe(){
            //訪問(wèn)不了外部類的成員
        }
    }

}
class Outer2{
    var name = "saf"
    inner class Inner{
        fun exe(){
            println(name)
        }
    }
}
fun uu(){
    Outer2().Inner().exe()
}
//枚舉,枚舉類實(shí)例可數(shù)，密封類子類可數(shù)
enum class Week{
    星期一,星期二,星期三,星期四,星期五,星期六,星期日
}
enum class Week2(var arg1:String,var arg2:String){
    YI("22","ee"),
    ER("44","gg")
}
fun dd(){
    Week2.YI.arg1 = "555"
}
var jj  = Week2.YI.arg1

//密封類構(gòu)造函數(shù)是私有的，因此密封類的子類必須在內(nèi)部或同一文件內(nèi)
sealed class HHH{
    object AAA : HHH() {}
    class BBB: HHH(){}
}
class CCC:HHH(){
    fun hh(){}
}
//數(shù)據(jù)類,必須val或var修飾，主構(gòu)造至少一個(gè)參數(shù)
//此類編譯器可以自動(dòng)生成equals，hashcode等方法
data class Bean(val hhh: HHH){}
//單例
object Singleton{
    var name = "單例"
    fun hj(){

    }
}
fun call(){
    Singleton.name = "111"
    Singleton.hj()
}

//伴生對(duì)象,kotlin中的靜態(tài)變量，類加載時(shí)初始化，和類生命周期一樣
class ddd{
    companion object 伴生對(duì)象名稱{//(也可以不寫名稱)
        fun ooo(){}
    }
}
fun ttt(){
    ddd.伴生對(duì)象名稱.ooo()

}
//委托代理模式 AA委托給JJJ
interface AA{
    fun aa()
}
class JJJ:AA{
    override fun aa() {

    }
}

//一
class P:AA by JJJ(){}
class PP(jjj: JJJ):AA by jjj

fun uuu(){
    //一
    var p:P = P()
    p.aa()
    //
    var jjj =JJJ()
    PP(jjj).aa()
}
//屬性委托,child委托給parent,也就是，委托類監(jiān)聽被委托類
class Parent{
    var name:Int = 0
    //setValue() 和 getValue() 方法前必須用 operator 關(guān)鍵字修飾
    //
    //getValue()方法返回類型必須與委托屬性相同或是其子類
    //
    //如果委托屬性是 val 類型，被委托方法只需要實(shí)現(xiàn) getValue()， 如果是 var 類型，則需要實(shí)現(xiàn)
    //getValue() 和 setValue()
    operator fun getValue(child: Child, property: KProperty<*>): Int {
        println("getValue")
        return name
    }

    operator fun setValue(child: Child, property: KProperty<*>, i: Int) {
        println("setValue")

    }
}
class Child{
    var name:Int by Parent()
    fun ooo(){
        println("被委托類的方法")
    }
}
fun LLL(){
    val child:Child = Child()
    child.name=100

}
//延遲加載，變量被訪問(wèn)時(shí)才會(huì)初始化,val ** by lazy
//執(zhí)行第一句話
//執(zhí)行中間一句話
//執(zhí)行最后一句//初始化完
//safsdfsf//開始執(zhí)行，只會(huì)執(zhí)行最后一句
//safsdfsf
//safsdfsf
fun kkk(){
    val name by lazy {
        println("執(zhí)行第一句話")
        println("執(zhí)行中間一句話")
        println("執(zhí)行最后一句")
        "safsdfsf"
    }
    println(name)
    println(name)
    println(name)
}