11.3

1.1

object base42
object class05 {
 object  Mytool {
  val PI = 3.14
  def Area(r:Double):Double={
   PI*r*r
  }
 }
 def main(args:Array[String]):Unit = {
  println( MyTool.PI)
  println( MyTool.Area(10))
 }
}

1.2

object base46 object class06{ class Student() { private val hobby ="打游戏" } object Student { def introduce(stu:Student):Unit = { println(s"我的爱好是:${stu.hobby}") } } def amin(args:Array[String]):Unit = { val stu1 = new Student() Student.introduce(stu1) } }

1.3

object base46
object class06 {

  class Student private() {
    object Student {
      private val instance = new Student()

      def getInstance(): Student = {
        instance
      }
    }

    def main(args: Array[String]): Unit = {
      val stu1 = Student.getInstance()
      val stu2 = Student.getInstance()
      println(stu1 == stu2)
    }
  }
}

1.4

object base46
object class06 {

  class Logger(var filename:String){
  }
  object Logger {
    def apply(filename:String):Logger = {
      println("appLy...")
      new Logger(filename)
    }
  }
  def main(args:Array[String]):Unit = {
    val log1 = logger("test.log")
    println(log1.filename)
  }
}