学习内容

1.类的声明
2.抽象类与接口
3.伴生类
4.数据类

package day1


class DemoClass

fun main(args:Array<String>){
    val demo = DemoClass()
    println(demo)
    println(demo is DemoClass)
    println(demo::class)
    var p = Person1("Tom",30,1)
    println(p)

    var p2 = Person2()
    p2.age = 30
    p2.name = "Tim"
    p2.sex = "M"
    println(p2)
    var rc = Retangle(3.0,4.0,5.0)
    println(rc.area())
    rc.onClick()
    var cl = Circle(3.0,4.0,10.0)
    println(cl.area())
    cl.onClick()
    val pp = Project()
    pp.print()
    println(User.name)
    println(User.password)
    User.hello() //与Java使用方式一样
    DataProcessor.processData()
    val loginUser = LoginUser("admin","123")
    val (username,password) = loginUser
    println("username=${username},password=${password}")
    val map = mapOf(1 to "A",2 to "B",3 to "C")
    println(map)
}

/**
 * 伴生类
 *一个类只能有一个伴生类
 */
class DataProcessor{
    companion object DataProcessor{
        fun processData(){
            println("I am a processor class")
        }
    }
}

/**
 * object
 * 使用object关键字声明一个单例
 */
object User{
    val name:String = "Admin"
    val password:String = "Admin"

    fun hello(){
        println("Hello world")
    }
}

interface ProjectS{
    var name:String
    var age:Int
    fun come()
    fun print(){
        println("project save")
    }
}

class Project:ProjectS{
    override var name: String
        get() = name
        set(value) {
            this.name = value
        }
    override var age: Int
        get() = age
        set(value) {
            this.age = value
        }

    override fun come() {
        super<ProjectS>.print()
        println("Project coming")
    }

}

/**
 * 抽象类
 */
abstract class Shape{
    //抽象类对成员也必须是抽象的
    abstract var width:Double
    abstract var height:Double
    abstract var radius:Double
    abstract fun area():Double //抽象方法

    /**
     * 默认是final，不可重写
     * 如果想要重写改方法需要在
     * 方法前加open关键字
     */
    open fun onClick(){
        println("Item click")
    }
}

class Circle(override var width: Double, override var height: Double,
             override var radius: Double): Shape() {
    override fun area(): Double {
        return Math.PI*radius*radius
    }

    override fun onClick() {
        super.onClick()
        println("Circle click")
    }
}

class Retangle(override var width: Double, override var height: Double,
               override var radius: Double):Shape(){
    override fun area(): Double = width*height
}


class Person2{
    lateinit var name:String; //lateinit表示延迟初始化
    var age:Int = 0;//lateinit不能修饰Int类型
    lateinit var sex:String

    //次级构造方法
    constructor(name: String, age: Int, sex: String) {
        this.name = name
        this.age = age
        this.sex = sex
    }

    constructor(name: String) {
        this.name = name
    }

    constructor(name: String, age: Int) {
        this.name = name
        this.age = age
    }

    constructor()


    override fun toString(): String {
        return "Person(name:$name,age:$age,sex:$sex)"
    }

}

/**
 * 构造方法声明
 */
class Person1(var name:String,var age:Int,var sex:Int){
    override fun toString(): String {
        return "Person(name:$name,age:$age,sex:$sex)"
    }
}

/**
 * 数据类
 * 主构造函数至少包含一个参数
 * 参数必须标示为val或者var
 * 不能为abstract，open，sealed，inner
 * 不能继承其他类
 *
 */
data class LoginUser(val name:String,val password:String) {
}