Package groovy.transform

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.
java.lang.String[]	excludes	Property names to exclude in the comparison algorithm.
java.lang.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

java.lang.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

java.lang.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