companion

What is a companion object? Companion object is nothing but a singleton object which will have same name as the class name and it will hold all the static methods and members. Since, Scala doesn’t support definition of static methods in the class we have to create the companion object. Both the class and companion object should need to have same name and should be present in the same source file. Consider the below example – class ListToString private(list: List[Any]) { def size(): Int = { list.length } def makeString(sep: String = ","): String = { list.mkString(sep) } } object ListToString { def makeString(list: List[Any], sep: String = ","): String = { list.mkString(sep) } def apply(list: List[Any]): ListToString = new ListToString(list) } Class ListToString defined with two ...