Scala this

In scala, this is a keyword and used to refer current object. You can call instance variables, methods, constructors by using this keyword.

Scala this Example

In the following example, this is used to call instance variables and primary constructotr.

class ThisExample{
    var id:Int = 0
    var name: String = ""
    def this(id:Int, name:String){
        this()
        this.id = id
        this.name = name
    }
    def show(){
        println(id+" "+name)
    }
}

object MainObject{
    def main(args:Array[String]){
        var t = new ThisExample(101,"Martin")
        t.show()
    }
}

Output:

101 Martin

Scala Constructor Calling by using this keyword

In the following example this is used to call constructor. It illustrates how we can call constructor from other constructor. You must make sure that this must be first statement in the constructor while calling to other constructor otherwise compiler throws an error.

class Student(name:String){
    def this(name:String, age:Int){
        this(name)
        println(name+" "+age)
    }    
}

object MainObject{
    def main(args:Array[String]){
        var s = new Student("Rama",100)
    }
} 

Output: