Scala constructor how to convert this in Scala language

Question

Hi I need help how to convert this in Scala with two constructor.

public class Configure {
  private final Config config;

  public Configure(String confFileName) {
    config = ConfigFactory.load(confFileName);
  }

  public Configure() {
    config = ConfigFactory.load();
  }

  public String getString(String name) {
    return config.getString(name);
  }
}

Possible duplicate of [Scala constructor overload?](https://stackoverflow.com/questions/1095329/scala-constructor-overload) — Brian McCutchon, Feb 19 '19 at 21:47

score 1 · Answer 1 · answered Feb 19 '19 at 21:54

1

class Configure(private val config :Config) {
  def this()                     = this(ConfigFactory.load())
  def this(confFileName :String) = this(ConfigFactory.load(confFileName))
}

answered Feb 19 '19 at 21:54

jwvh

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Strictly speaking, the primary constructor should be private as well for equivalence with Java. – Alexey Romanov Feb 20 '19 at 08:02
Why use `private val config` rather than just `config`? What is the advantage of making it a private member rather than just a constructor parameter? – Tim Feb 20 '19 at 14:50

score 1 · Answer 2 · answered Feb 20 '19 at 08:38

In Scala you would typically do this using a companion object:

class Configure private (config: Config) {
  def configString(name: String) = config.getString(name)
}

case object Configure {
  def apply(confFileName: String ) =
    new Configure(ConfigFactory.load(confFileName))

  def apply() =
    new Configure(ConfigFactory.load())
}

This nicely separates the behaviour of the class from the different ways of creating it.

[ I renamed getString because "getters" don't usually begin with get in Scala, they are just the name of the value being retrieved. ]

Scala constructor how to convert this in Scala language

2 Answers2