Overview of how to to construct modern enums using lambda.

We have enum JobTitle

public enum JobTitle { PRESIDENT, VICE_PRESIDENT, OFFICER, MANAGER, DEVELOPER, CONSULTANT, IMPLEMENTATION_OFFICER, INTERN; } 

and groups:

• ADMINISTRATION = PRESIDENT, VICE_PRESIDENT

• OPERATIONAL = MANAGER, OFFICER

• it is a good practice to provide static methods that return predicates:

  public static Predicate<JobTitle> administration() { return JobTitle::isAdministration; } public static Predicate<JobTitle> operational() { return JobTitle::isOperational; } 

  where, obviously:

  public boolean isAdministration() { return ADMINISTRATION.contains(this); } public boolean isOperational() { return OPERATIONAL.contains(this); } 

• and a stream() method:

  public static Stream<JobTitle> stream() { return Arrays.stream(values()); } 

because later in the code it's easy to write very expressive code (like in JobTitleTest):

@Test public void isBusinessShowcase() { JobTitle.stream() .filter(administration().or(operational())) .forEach(title -> System.out.println("Performed action for: " + title)); }