Annotation Type Sortable


@Retention(RUNTIME)
@Target(TYPE)
public @interface Sortable
A class annotation used to make a class Comparable by (potentially) multiple Comparators. As an example, given this class:
 @Sortable class Person {
     String first
     String last
     Integer born
 }
 
The generated Groovy class will:
  • implement the Comparable interface
  • have a compareTo method based on the first, last and born properties (priority ordering will be according to the ordering of property definition, highest first, unless 'includes' is used; in which case, priority will be according to the order given in the includes list)
  • have three Comparator methods named comparatorByFirst, comparatorByLast and comparatorByBorn
  • sort by natural order by default, reversed natural order can be specified
The properties within the class must themselves be Comparable or @Sortable.

More examples:

 //--------------------------------------------------------------------------
 import groovy.transform.Sortable
 import groovy.transform.ToString

 @Sortable
 @ToString
 class Course {
     // Order of properties determines priority when sorting
     String title
     Date beginDate
     Integer maxAttendees  // int doesn't implement Comparable, so use Integer
 }


 final Course groovy = new Course(
         title: 'Groovy', beginDate: new Date() + 7, maxAttendees: 40)
 final Course groovy2 = new Course(
         title: 'Groovy', beginDate: new Date() + 2, maxAttendees: 50)
 final Course grails = new Course(
         title: 'Grails', beginDate: new Date() + 1, maxAttendees: 20)


 final List<Course> courses = [groovy, groovy2, grails]
 assert courses.last().title == 'Grails'

 // Use toSorted() method to sort
 final List<Course> sorted = courses.toSorted()

 assert sorted.first().title == 'Grails'
 assert sorted.last().title == 'Groovy'
 assert sorted.maxAttendees == [20, 50, 40]
 
 //--------------------------------------------------------------------------
 // Order of fields for includes determines priority when sorting
 import groovy.transform.Sortable
 import groovy.transform.ToString

 @Sortable(includes = ['title', 'maxAttendees'])
 // Or @Sortable(excludes = ['beginDate'])
 @ToString
 class Course {
     String title
     Date beginDate
     Integer maxAttendees
 }

 final Course groovy = new Course(
         title: 'Groovy', beginDate: new Date() + 7, maxAttendees: 40)
 final Course groovy2 = new Course(
         title: 'Groovy', beginDate: new Date() + 2, maxAttendees: 50)
 final Course grails = new Course(
         title: 'Grails', beginDate: new Date() + 1, maxAttendees: 20)


 final List<Course> courses = [groovy, groovy2, grails]

 // Use toSorted() method to sort
 final List<Course> sorted = courses.toSorted()

 assert sorted.first().title == 'Grails'
 assert sorted.last().title == 'Groovy'
 assert sorted.maxAttendees == [20, 40, 50]

 //--------------------------------------------------------------------------
 // Static methods to create comparators.
 final Comparator byMaxAttendees = Course.comparatorByMaxAttendees()
 final List<Course> sortedByMaxAttendees = courses.sort(false, byMaxAttendees)

 assert sortedByMaxAttendees.maxAttendees == [20, 40, 50]
 // beginDate is not used for sorting
 assert sortedByMaxAttendees[2].beginDate < sortedByMaxAttendees[1].beginDate

 assert Course.declaredMethods.name.findAll { it.startsWith('comparatorBy') }.toSorted() == ['comparatorByMaxAttendees', 'comparatorByTitle']

 //--------------------------------------------------------------------------
 // Sorting by max attendees using reversed order
 import groovy.transform.Sortable
 import groovy.transform.ToString

 @Sortable(includes = ['points'], reversed = true)
 @ToString
 class LeaderBoardEntry {
     String team
     int points
 }


 final LeaderBoardEntry teamA = new LeaderBoardEntry(team: "Team A", points: 30)
 final LeaderBoardEntry teamB = new LeaderBoardEntry(team: "Team B", points: 80)
 final LeaderBoardEntry teamC = new LeaderBoardEntry(team: "Team C", points: 50)

 final List<LeaderBoardEntry> leaderBoard = [teamA, teamB, teamC].toSorted()

 assert leaderBoard.first().team == 'Team B'
 assert leaderBoard.last().team == 'Team A'
 assert leaderBoard.points == [80, 50, 30]

 
  • Optional Element Summary

    Optional Elements
    Modifier and Type Optional Element Description
    boolean allNames
    Whether to include all fields and/or properties in the comparison algorithm, including those with names that are considered internal.
    boolean allProperties
    Whether to include all properties (as per the JavaBean spec) in the comparison algorithm.
    String[] excludes
    Property names to exclude in the comparison algorithm.
    String[] includes
    Property names to include in the comparison algorithm.
    boolean includeSuperProperties
    Whether to include super properties in the comparison algorithm.
    boolean reversed
    Set to true so that comparator uses reversed natural order.
  • Element Details

    • includes

      String[] includes
      Property names to include in the comparison algorithm. Must not be used if 'excludes' is used. The default value is a special marker value indicating that no includes are defined; all properties are included if 'includes' remains undefined and 'excludes' is explicitly or implicitly an empty list.
      Default:
      {"<DummyUndefinedMarkerString-DoNotUse>"}
    • excludes

      String[] excludes
      Property names to exclude in the comparison algorithm. Must not be used if 'includes' is used.
      Default:
      {}
    • reversed

      boolean reversed
      Set to true so that comparator uses reversed natural order.
      Since:
      2.5.0
      Default:
      false
    • includeSuperProperties

      boolean includeSuperProperties
      Whether to include super properties in the comparison algorithm. Groovy properties and potentially JavaBean properties (in that order) from superclasses come before the members from a subclass (unless 'includes' is used to determine the order).
      Since:
      2.5.2
      Default:
      false
    • allProperties

      boolean allProperties
      Whether to include all properties (as per the JavaBean spec) in the comparison algorithm. Groovy recognizes any field-like definitions with no explicit visibility as property definitions and always includes them in the comparison algorithm. Groovy also treats any explicitly created getXxx() or isYyy() methods as property getters as per the JavaBean specification. Set this flag to false explicitly exclude such properties. JavaBean properties come after any Groovy properties for a given class (unless 'includes' is used to determine the order).
      Since:
      2.5.2
      Default:
      true
    • allNames

      boolean allNames
      Whether to include all fields and/or properties in the comparison algorithm, including those with names that are considered internal.
      Since:
      2.5.2
      Default:
      false