How to use Named Parameters in Scala? What is the use of Named Parameters in Scala?

Question

How to define Default parameters in Scala? What is the use of Default Parameters in Scala? How to avoid implementing Auxiliary Constructors or Multiple Constructors in Scala?

Answer 1

When calling methods and functions, you can use the name of the variables explicitly in the call, like so:

  def printName(first:String, last:String) = {
    println(first + " " + last)
  }
  printName("John","Smith")
  // Prints "John Smith"
  printName(first = "John",last = "Smith")
  // Prints "John Smith"
  printName(last = "Smith",first = "John")
  // Prints "John Smith"

Note that once you are using parameter names in your calls, the order doesn’t matter, so long as all parameters are named. This feature works well with default parameter values:

  def printName(first:String = "John", last:String = "Smith") = {
    println(first + " " + last)
  }
  printName(last = "Jones")
  // Prints "John Jones"

Since you can place the parameters in any order you like, you can use the default value for parameters that come first in the parameter list.