Question

In my project, I have such class :

class Statut {
    String satDomain;
    String staCode;
}

But working with Strings is not what I want. It is too permisive and using constants is not enough.

I wanted to use enums but find a problem :

class Statut {
    Domain satDomain;
    StatutCode staCode;
}
enum Domain { }
enum StatutCode { }

This solution is far better, but you can set a StatutCode that is not in the selected Domain.

Did you find a solution in your project to such problem ?

Thank for your help

Fluminis

Answer 1

Actually slight improvement on extraneon’s answer.

Define StatutCode enum first, and then assign EnumSet< StatutCode > to each Domain enum value. Then the validation is pretty simple in Statut constructor

enum StatutCode
{
  ONE,
  TWO,
  THREE,
  FOUR
};

enum Domain
{
  DOMAIN_1( EnumSet.of( StatutCode.ONE, StatutCode.TWO ) ),
  ...
  DOMAIN_N( EnumSet.of( StatutCode.TWO, StatutCode.THREE ) );

  private final EnumSet< StatutCode> validStatCodes;

  Domain( EnumSet< StatutCode > validStatCodes )
  {
    this.validStatCodes = validStatCodes;
  }

  public boolean isValidCode ( final StatutCode code )
  {
    return validStatCodes.contains( code );
  }
}

class Statut {
    final Domain staDomain;
    final StatutCode staCode;

    Statut(
      final Domain staDomain,
      final StatutCode staCode
    )
    {
      if ( ! staDomain.isValidCode( staCode ) )
      {
        throw new IllegalArgumentException(
            "Invalid code " + staCode + " for domain " + staDomain
          );
      }

      this.staDomain = staDomain;
      this.staCode = staCode;
    }

}