Kotlin basic learning 15

Catalog

1.Kotlin Language definition extension function learning

2.Kotlin Define extended function learning on the super class of language

3.Kotlin Language generic extension function learning

4.Kotlin Standard functions and generic extension functions of language

5.Kotlin Extended properties of language

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1.Kotlin Language definition extension function learning

class KtBase113(val name : String,val age : Int,val sex : Char)
// Add extension function 
fun KtBase113.show(){
    println(" I am a show function ,name：$name,age：$age,sex:$sex")
}
fun KtBase113.getInfo() = " I am a getInfo function ,name:$name,age：$age,sex:$sex"
fun String.addExtAction(number:Int) = this + "@".repeat(number)
fun String.showStr() = println(this)
// TODO 113.Kotlin Language definition extension function learning 
fun main(){
    val p = KtBase113(" Zhang San ",22,' male ')
    p.show()
    println(p.getInfo())
    println("Bxb".addExtAction(6))
    println("Bxb".addExtAction(2))
    // This is my log information 
    "Bxb".showStr()
}

2.Kotlin Define extended function learning on the super class of language

data class ResponseResult1(val msg:String,val code : Int)
data class ResponseResult2(val msg:String,val code : Int)
data class ResponseResult3(val msg:String,val code : Int)
data class ResponseResult4(val msg:String,val code : Int)
// Extend the superclass with a function 
fun Any.showPrintlnContent() = println(" The current content is ：$this")
fun Any.showPrintlnContent2() : Any{
    println(" The current content is ：$this")
    return this
}
// TODO 114.Kotlin Define extended function learning on the super class of language 
fun main(){
    ResponseResult1("login success",200).showPrintlnContent()
    ResponseResult2("login success",200).showPrintlnContent()
    ResponseResult3("login success",200).showPrintlnContent()
    ResponseResult4("login success",200).showPrintlnContent()
    "Bxb".showPrintlnContent()
    val number1 = 666666
    number1.showPrintlnContent()
    val number2 = 456.32f
    number2.showPrintlnContent()
    val sex = ' male '
    sex.showPrintlnContent()
    println()
    ' Woman '.showPrintlnContent2().showPrintlnContent2().showPrintlnContent2()
    "Bxb is OK".showPrintlnContent2().showPrintlnContent2()
    //KT Built in extension function , Redefined by us , It belongs to covering , The extension function defined by ourselves will be called first 
}

3.Kotlin Language generic extension function learning

//1.String Type output length 
fun <T> T.showContentInfo() = println("${if (this is String) " Your string length is :$length" else " You are not a string   Your content is ：$this"}")
//2. Display the call time 
fun <I> I.showTime() = println(" Your current call time is ：${System.currentTimeMillis()}, The content is ：$this")
//3. Display the contents of the caller 
fun <INPUTTYPE> INPUTTYPE.showTypesAction() =
    when(this) {
        is String -> " So you are String type "
        is Int -> " So you are Int type "
        is Char -> " So you are Char type "
        is Float -> " So you are Float type "
        is Double -> " So you are Double type "
        is Boolean -> " So you are Boolean type "
        is Unit -> " So you are Unit type "
        else -> " Unknown type "
    }
fun commenFun(){}
// TODO 115.Kotlin Language generic extension function learning 
fun main(){
    145.showContentInfo()
    'C'.showContentInfo()
    false.showContentInfo()
    145.3f.showContentInfo()
    145.56.showContentInfo()
    "Bxb".showContentInfo()
    commenFun().showContentInfo()
    println()
    145.showTime()
    'C'.showTime()
    false.showTime()
    145.3f.showTime()
    145.56.showTime()
    "Bxb".showTime()
    commenFun().showTime()
    println()
    println(145.showTypesAction())
    println('C'.showTypesAction())
    println(false.showTypesAction())
    println(145.3f.showTypesAction())
    println(145.56.showTypesAction())
    println("Bxb".showTypesAction())
    println(commenFun().showTypesAction())
}

4.Kotlin Standard functions and generic extension functions of language

// TODO 116.Kotlin Standard functions and generic extension functions of language 
fun main(){
    val r : String = "Bxb".mLet {
        it
        true
        "OK"
    }
    123.mLet{
        it
    }
    'C'.mLet {
        it
    }
    // Universal type , Any kind of , You can use mLet
    val r2 : String = "Bxb2".let {
        it
        1542.6f
        "Bxb"
    }
}
// private  Privatization 
// inline  Our function is a higher-order function , So we use inline , do lambda The optimization of the , Performance improvement 
// fun<I,O>  In the function , Declare two generics , The function of generic  I Input  Input,O Output Output
// I.mLet  Yes I Input Input Function extension , The name of the extension function is mLet, signify , All types , Universal type , Both can be used.  xxx.mLet
// lambda: (I) -> O I Input ,O Output 
// ：O  According to the user's return type , Change and change 
// lambda(this) I  Function extension , In the whole extension function ,this==I In itself 
private inline fun<I,O> I.mLet(lambda:(I) -> O) : O = lambda(this)

5.Kotlin Extended properties of language

val myStr : String = "AAA"
val String.myInfo:String
    get() = "Bxb"
// Printout   also   call chaining （ Only String Have such qualifications ）
fun String.showPrintlin() : String{
    println(" Printout   also   call chaining （ Only String Have such qualifications ）: Content $this")
    return this
}
val String.StringAllInfoValueVal
    get() = " At present ${System.currentTimeMillis()} This point in time is called once , The current value is ：$this, The current string length is ：$length"
// TODO 117.Kotlin Extended properties of language 
fun main(){
    val str : String = "ABC"
    println(str.myInfo)
    str.showPrintlin().showPrintlin().showPrintlin()
    str.myInfo.showPrintlin().showPrintlin()
    "Bxb handsome guy ".StringAllInfoValueVal// Extended attributes 
        .showPrintlin().showPrintlin() // spread function 
}