Scala学习 2 Scala面向对象

object Scala_study3 {  def main(args: Array[String]): Unit = {    /*    * 2.1 Scala面对对象详解    *    * 2.1.1 Scala中class和object初介紹    * scala中class的定义与java类似,区别是在Scala中,类名不是必须和文件名相同,且一个文件中可以定义多个class.    * Scala中的class不存在静态成员,Java中的静态成员由Scala中的object对象替代,    * 当object对象名与class名相同时称object为class的[伴生对象]    * */    //2-1 Scala类的定义实战    class HiScala{      private val name:String = "zhangsan"      def sayName(): Unit ={        println(name)      }      def getName = name    }    val hiScala = new HiScala    hiScala.sayName()    println(hiScala.getName)    //2-2 object定义实战    object Person{      println("构造函数调用一次")      val age = 10      def getAge = age    }    Person.getAge    Person.getAge    //2-3 继承    abstract class Animal{      def eat = {        println("Eat food !!!")      }      def run    }    class Cat extends Animal{      override def eat: Unit = {        println("Eat mouse!!!")      }      override def run: Unit = {        println("cat is running...")      }    }    class Dog extends Animal{      override def run: Unit = {        println("dog is running")      }    }    val c = new Cat    c.eat    c.run    val d = new Dog    d.eat    d.run  }  /*  * Eat mouse!!!    cat is running...    Eat food !!!    dog is running  * */  //2-4 子类不能重写父类中被final修饰的方法和属性  /*  * 2.1.2 主构造器和辅助构造器  * */  //2-5 Scala默认构造器在类上  class Person1{  }//默认无参构造器  class Person2(name:String){    println(name)  }//默认带一个字符串参数的构造器  //2-6 构造器重载(辅助构造器)  class Person3(name:String){    println(name)    def this(name:String,age:Int)    {      this(name)      println(name + ":" + age)    }    def this(name:String,age:Int,sex:String)    {      this(name,age)      println(name + ":" + age + ":" + sex)    }  }  //2-7 构造器重载(多参数默认构造器)  class Student1(name:String,age:Int,sex:String){    println(name + ":" + age + ":" + sex)  }  val s = new Student1("chenjie",23,"male")  /*  * 2.1.3 类的字段和方法彻底精通  * */  class Person4{    var name : String = "zhangsan"    var age = 30    val sex = "famale"    def seyHi = println("Hi!!!")    def increase(age:Int):Int = this.age + age  }  val p = new Person4  println(p.name)  println(p.sex)  p.name = "lisi"  //2-9 复写setter  class Person5{    private var myName = "Flink"    def name = this.myName    def name_=(newName:String){//等号两边不能有空格      myName = newName      println("hi:" + myName)    }  }  //2-10 自定义setter  class Person6{    private var myName = "Flink"    def name = this.myName    def update(newName:String): Unit ={      myName = newName    }  }  //2-11 private[this]实战,用此修饰的字段或方法只能被当前对象访问,当前对象的其他实例无法访问.  /*  * 2.1.4 抽象类 接口的实战详解  * */  abstract class Person7(name:String){    println(this.name)    private var age = 20    val sex : String = "male" //抽象类中的字段不能用abstract修饰  }  //Scala的特质相当于Java中的接口,不过特质中可以有实现的方法  //在Scala中实现特质被成为混入,混入的第一个特质用关键字extends,混入更多的用with  trait Person8{    val name : String    val age = 30    def eat(str:String): Unit ={      println(str)    }  }  trait Worker{    val age = 25    def work: Unit ={      println("Working....")    }  }  class Student2 extends Worker with Person8{    val name : String = "zhangsan"    override val age: Int = 15  //两个特质中的相同字段发生冲突时必须重写该字段  }  /*  * 2.1.5 Scala Option类详解  * Scala中的Option[T]可以是一些[T]或者None对象,它代表一个缺失值  * 例如hashMap的get方法,可能找到则返回值,可能找不到则返回null,这就是一个Option  * */  /*  * 2.1.6 objetc的提取器  * objetc中提供了apply方法,作用是在创建对象时不直接用new,而是直接用对象加参数,这时调用类伴生对象的apply方法  * */  var arr1 = Array(1,2,3)  arr1 = Array.apply(1,2,3)  //2-18 提取器  object ExtractorTest{    def apply(user:String,domain:String)={      user + "@" + domain    }    def unapply(str: String): Option[(String,String)] = {      val parts = str.split("@")      if(parts.length == 2){        Some(parts(0),parts(1))      }      else        {          None        }    }  }}