笔记：kotlin 学习第四天

1. 中缀表达式

   /**
    * @ 文件名:   `01.中缀表达式`
    * @ 创建者:   ty
    * @ 时间:    2018/7/20 14:27
    * @ 描述:    infix
    * Tom sayHelloTo John
    */
   fun main(args: Array) {
   
       val pair = "a" to 1
   
       val tom = Person()
       tom.sayHelloTo("John")
   
       tom sayHelloTo "John"//方法前面添加infix关键字
   }
   
   class Person {
       infix fun sayHelloTo(name: String) {
           "你好$name"
       }
   }
   

2. 类委托

   /**
    * @ 文件名:   `02.类委托`
    * @ 创建者:   ty
    * @ 时间:    2018/7/20 14:27
    * @ 描述:    by
    * 小头爸爸委托大头儿子洗碗
    */
   fun main(args: Array) {
       val smallHeadFather = SmallHeadFather()
       smallHeadFather.wash()
   }
   
   interface WashPower {
       fun wash()
   }
   
   class SmallHeadFather : WashPower by BigHeadSon()
   
   class BigHeadSon : WashPower {
       override fun wash() {
           println("大头儿子洗碗")
       }
   }
   

3. 类委托实现二

   /**
    * @ 文件名:   `03.类委托实现二`
    * @ 创建者:   ty
    * @ 时间:    2018/7/20 14:27
    * @ 描述:    by
    */
   fun main(args: Array) {
   
       val bigHeadSon = BigHeadSon()
       val smallHeadSon = SmallHeadSon()
   
       //val bigHeadFather = BigHeadFather(bigHeadSon)
       val bigHeadFather = BigHeadFather(smallHeadSon)
       bigHeadFather.wash()
   
   }
   
   interface WashPower {
       fun wash()
   }
   
   class SmallHeadSon : WashPower {
       override fun wash() {
           println("小头儿子开始洗碗")
       }
   }
   
   class BigHeadSon : WashPower {
       override fun wash() {
           println("大头儿子开始洗碗")
       }
   }
   
   class BigHeadFather(var washPower: WashPower) : WashPower by washPower
   

4. 类委托功能加强

   /**
    * @ 文件名:   `04.类委托功能加强`
    * @ 创建者:   ty
    * @ 时间:    2018/7/20 14:31
    * @ 描述:
    */
   fun main(args: Array) {
       val smallHeadSon = SmallHeadSon()
       val bigHeadSon = BigHeadSon()
   
       val bigHeadFather = BigHeadFather(smallHeadSon)
       //val bigHeadFather = BigHeadFather(bigHeadSon)
   
       bigHeadFather.wash()
   }
   
   interface WashPower {
       fun wash()
   }
   
   class SmallHeadSon : WashPower {
       override fun wash() {
           println("小头儿子开始洗碗")
       }
   }
   
   class BigHeadSon : WashPower {
       override fun wash() {
           println("大头儿子开始洗碗")
       }
   }
   
   class BigHeadFather(var washPower: WashPower) : WashPower by washPower {
       override fun wash() {
           println("付给洗碗的儿子一块钱")
           washPower.wash()
           println("碗洗的不错，下次还找你洗")
       }
   }
   

5. 属性委托

   /**
    * @ 文件名:   `05.属性委托`
    * @ 创建者:   ty
    * @ 时间:    2018/7/20 14:41
    * @ 描述:    by
    * 妈妈帮忙保管压岁钱
    */
   
   fun main(args: Array) {
       val bigHeadSon = BigHeadSon()
   
       bigHeadSon.money = 100//收到100块压岁钱
   
       println(bigHeadSon.money)//50 被代保管了一半
   
   }
   
   class BigHeadSon {
       var money: Int by Mother()
   }
   
   class Mother {
   
       var moneySon = 0
       var moneyMother = 0
   
       operator fun getValue(bigHeadSon: BigHeadSon, property: KProperty<*>): Int {
           return moneySon
       }
   
       operator fun setValue(bigHeadSon: BigHeadSon, property: KProperty<*>, i: Int) {
           moneySon = i / 2
           moneyMother = i / 2
       }
   }
   

6. 惰性加载

   /**
    * @ 文件名:   `06.惰性加载`
    * @ 创建者:   ty
    * @ 时间:    2018/7/20 14:41
    * @ 描述:    by lazy {  }
    * 字段必须 val 修饰
    * 1,by lazy 放到成员变量中，可以单独存在
    * 2，by lazy 返回值就是最后一行
    * 3, by lazy 是线程安全的
    */
   
   fun main(args: Array) {
       val lazy = Lazy()
       println(lazy.name)
       println(lazy.name)
       println(lazy.name)
   }
   
   class Lazy {
       val name: String by lazy {
           println("只初始化一次")
           "懒加载"
       }
   }
   

7. 延迟加载

   /**
    * @ 文件名:   `07.延迟加载`
    * @ 创建者:   ty
    * @ 时间:    2018/7/20 15:03
    * @ 描述:    lateinit
    *
    * 1.by lazy 和lateinit  都可以单独使用或者放到成员变量中使用
    * 2.by lazy 知道具体值   用的时候再加载,lateinit  不知道具体值  后面再赋值
    * 3.by lazy变量必须通过val修饰  lateinit需要通过var修饰
    */
   fun main(args: Array) {
       val user = User()
       println(user.name + user.phone)
   
       user.name = "林青霞"
       user.phone = "110"
   
       title = "标题"
   
       println(user.name + user.phone)
   }
   
   
   lateinit var title: String
   //lateinit var money: Byte //lateinit不支持原始数据类型
   
   class User {
       lateinit var name: String
       lateinit var phone: String
   }
   

8. 扩展函数

   /**
    * @ 文件名:   `08.扩展函数`
    * @ 创建者:   ty
    * @ 时间:    2018/7/20 15:10
    * @ 描述:    String.myIsEmpty()
    *
    * 判断字符串是否为空
    */
   
   fun main(args: Array) {
       val str = null
       //val str = "abc"
       val isEmpty = str?.myIsEmpty()
       println(isEmpty)
   
   }
   
   fun String.myIsEmpty(): Boolean {
       return this == null || this.isEmpty()
   }
   

9. kotlin中的object单例

   /**
    * @ 文件名:   `09.kotlin中的object单例`
    * @ 创建者:   ty
    * @ 时间:    2018/7/20 15:48
    * @ 描述:    object ClassName
    */
   
   fun main(args: Array) {
       println(SingleInstance.name)
       SingleInstance.login("110", "12345")
   }
   
   object SingleInstance {
       var name: String = "张三"//private static String name;
       fun login(phone: String, pwd: String) {
           println("登录成功: $phone + $pwd")
       }
   
       /* 实现单例的关键代码
       static {
           SingleInstance var0 = new SingleInstance();
           INSTANCE = var0;
           name = "张三";
       }*/
   }
   

10. 伴生对象

    /**
     * @ 文件名:   `10.伴生对象`
     * @ 创建者:   ty
     * @ 时间:    2018/7/20 16:21
     * @ 描述:    companion object {  }
     */
    fun main(args: Array) {
        val person = Person()
        println(person.age)
        println(Person.name)
    }
    
    class Person {
        //非静态属性
        var age = 10
    
        companion object {
            //静态属性
            var name = "林志玲"
        }
    }
    

11. 和Java一样的单例

    /**
     * @ 文件名:   `11.和Java一样的单例`
     * @ 创建者:   ty
     * @ 时间:    2018/7/20 16:35
     * @ 描述:
     */
    fun main(args: Array) {
        println(Utils.instance.isCanLogin("110"))
    }
    
    /**
     * 1,私有化构造方法：private constructor()
     * 2,初始化一个私有的静态成员变量：companion object { val instance}
     * 3,对外提供一个公共的方法返回该对象：by lazy { Utils() }
     */
    class Utils private constructor() {
    
        companion object {
            val instance by lazy { Utils() }//惰性加载，只会加载一次，并且线程安全的
        }
    
        fun isCanLogin(phone: String): Boolean {
            return phone.myIsEmpty() && phone.length == 11
        }
    }
    

12. 枚举

    /**
     * @ 文件名:   `12.枚举`
     * @ 创建者:   ty
     * @ 时间:    2018/7/20 16:35
     * @ 描述:   定义一个枚举类，星期一到星期天 Monday Tuesday Wednesday Thursday Friday Saturday Sunday
     *          并定义一个方法判断是否是工作日
     */
    fun main(args: Array) {
    
        println(todo(WEEK.TUESDAY))
        WEEK.values().forEach {
            println(it)
        }
    }
    
    enum class WEEK {
        MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY
    }
    
    fun todo(week: WEEK): String {
        return when (week) {
            in WEEK.MONDAY..WEEK.FRIDAY -> {
                "工作日"
            }
            WEEK.SATURDAY, WEEK.SUNDAY -> {
                "休息日"
            }
            else -> {
                "其他情况"
            }
        }
    }
    

13. 枚举加强

    /**
     * @ 文件名:   `13.枚举加强`
     * @ 创建者:   ty
     * @ 时间:    2018/7/20 16:35
     * @ 描述:    定义一个枚举类 初始化三原色 R G B
     */
    fun main(args: Array) {
        println(COLOR.RED.r)
        println(COLOR.GREEN.g)
        println(COLOR.BLUE.b)
    }
    
    enum class COLOR(var r: Int, var g: Int, var b: Int) {
        RED(255, 0, 0), GREEN(0, 255, 0), BLUE(0, 0, 255)
    }
    

14. 数据类

    /**
     * @ 文件名:   `14.数据类`
     * @ 创建者:   ty
     * @ 时间:    2018/7/20 16:35
     * @ 描述:    data class 定义一个JavaBean
     */
    
    fun main(args: Array) {
        val banner = Banner("title", "http://www.baidu.com", 10011)
        println(banner.title + banner.url +
                banner.component3())//第三个元素 id
        val (title1, url, id) = Banner("title", "http://www.baidu.com", 10011)
        println(url)
    
    }
    
    // BaseBean abcd = new Gson().fromJson("json", BaseBean.class);
    
    data class Banner(
            var title: String,
            var url: String,
            var id: Int)
    

15. 密封类

    /**
     * @ 文件名:   `15.密封类`
     * @ 创建者:   ty
     * @ 时间:    2018/7/20 16:49
     * @ 描述:    sealed class
     */
    fun main(args: Array) {
    
        println(hasRightSon(NedStark.SansaStark()))
    
        println(hasRightSon(JohnSnow()))
    }
    
    fun hasRightSon(stark: NedStark):Boolean{
        return when (stark) {
            is NedStark.RobStark -> {
                true
            }
            is NedStark.SansaStark ->{
                true
            }
            is NedStark.AryaStark->{
                true
            }
            is NedStark.BrandonStark->{
                true
            }
            else -> {
                false
            }
        }
    }
    
    //密封类封装的是类型 类型是确定的
    sealed class NedStark {
        class RobStark : NedStark()
        class SansaStark : NedStark()
        class AryaStark : NedStark()
        class BrandonStark : NedStark()
    }
    
    class JohnSnow : NedStark()