Scala—伴生类、半身对象，封装、继承

伴生类、伴生对象

伴生类

新建scala class

class Oop1 {
  def showInfo():Unit ={
    println("this is Oop1 class")
  }

//  def main(args: Array[String]): Unit = {
//    val oop = new Oop1
//    oop.showInfo()
//  }
}
//必须在object内才能执行

object Oop1Test{
  def main(args: Array[String]): Unit = {
    val oop = new Oop1()
    oop.showInfo()
  }
}

伴生对象

apply可以省略new方法

object Oop1{
	def apply(name: String, age: Int): Oop1 = new Oop1(name, age)
	//上面这条是伴生对象
	def main(args: Array[String]): Unit = {
	//直接写 Oop1("cp",18) 然后输入.var，就会自动生成
	val cp = Oop1("cp", 18)
	//类似于
	val oop1 = new Oop1("cp", 18)
	}
}

封装、继承

创建汽车抽象类

class BMW extends Car with Balance {
  override def brand: String = {
    println("BMW X6")
    "宝马高端 X6"
  }

  override def engine: String = {
    println("燃油涡轮增压")
    "燃油5T"
  }
}

特质

trait Balance{
  def balance:String
}

引用特质

class BMW extends Car with Balance {
  override def brand: String = {
    println("BMW X6")
    "宝马高端 X6"
  }

  override def engine: String = {
    println("燃油涡轮增压")
    "燃油5T"
  }

  override def balance: String = {
    println("独立悬挂")
    "独立悬挂"
  }
}

object TestCar{
  def main(args: Array[String]): Unit = {
    val bmw = new BMW
    bmw.balance
  }
}