kotlin 学习

基础

class Person{
    private var clo:(()->Unit)? = null
    public var name:String? = null
}
//扩展属性
val Person.kinds:Int
get() = 1

//扩展函数
fun Person.desc(){

    println("扩展函数")
}
enum class Direction {
    North,South,West,East
}
//lamada
fun testClosure(closure: ()->Unit) {

    closure()
}


1,  Double  64 ,Float   32, Long    64,Int  32,Short    16,Byte,
2,  break 和 continue 标签
    loop@ for (i in 1..100) {
        for (j in i..100) {
            if (...)
                break@loop
        }
    }
3, 构造函数
    1，class Customer(name: String) {} //一级
    2，class Person { // 二级
            constructor(parent: Person) {
                parent.children.add(this)
            }
        } 
4, 接口重写
        interface A {
            fun foo() { print("A") }
            fun bar()
        }
        
        interface B {
            fun foo() { print("B") }
            fun bar() { print("bar") }
        }
        
        class C : A {
            override fun bar() { print("bar") }
        }
        
        class D : A, B {
            override fun foo() {
                super.foo()
                super.foo()
            }
        }
        
4， 嵌套类
    class Outer {
        private val bar: Int = 1
        class Nested {
            fun foo() = 2
        }
    内部类
        class Outer {
            private val bar: Int = 1
            inner class Inner {
                fun foo() = bar
        }

延伸

class LearnOne {

    // 函数声明
    fun sum(a:Int, b:Int):Int {

        println(a+b)
        return a+b
    }
    // 自推导型的返回值
    fun sum1(a: Int, b: Int) = a + b

    // 返回无意义值 Unit， $ 获取参数值
    fun printSum(a: Int, b: Int): Unit {
        println("sum of $a and $b is ${a + b}")
    }
    // 字符串模版
    fun str(args:Array) {

        var a = 1
        val s1 = "a is $a"
        var s2 = "args[1] is ${args[0]}"
        println(s1)
    }
    // 可空值
    fun parseInt(str: String?): Int? {

        var valueInt = str?.toInt()
        return valueInt
    }
    // 高阶函数
    fun  locked(lock:Lock,v1:T,v2:T,body:(a:Int)->T):Boolean where T:Comparable{

        lock.lock()
        val a = body(100)

        println(a)
        return  v1 > v2
    }


    // 测试
    fun test() {

        val lock = ReentrantLock()

        var l1 = locked(lock,1,2, { a:Int ->

            1000
        })
        print(l1)

    }
}