Durga Gadiraju

Durga Gadiraju

Object Oriented Concepts – Objects

As part of this topic we will see about a special type of class called Object
Object

  • Scala is more object-oriented than Java because in Scala, we cannot have static members. Instead, Scala has singleton objects
  • Object is a keyword which represents singleton class.

Creating a Scala object
Example

object HelloWorld {
  def main(args: Array[String]): Unit = {
    println("Hello World")
}
}

Invoking the above main method from REPL

HelloWorld.main(Array(" "))

Companion Objects

  • A companion object is an object with the same name as a class and is defined in the same source file as the associated file.

Example

class Order(val orderId:Int,val orderDate:String,val orderCustomerId:Int,val orderStatus:String)
{
 println("I am inside Order Constructor")
 override def toString = "Order("+ orderId+ ","+ orderDate + ","+ orderCustomerId + ","+ 
 orderStatus +")"
}

object Order {
 def apply(orderId: Int, orderDate: String, orderCustomerId: Int, orderStatus:String): Order = {
 new Order(orderId, orderDate, orderCustomerId, orderStatus)
}
}
val order = Order.apply(1, "2013-10-01 00:00:00.000", 100,"COMPLETE")

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