[Java] Annotation Type Sortable
- groovy.transform.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 thefirst
,last
andborn
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 namedcomparatorByFirst
,comparatorByLast
andcomparatorByBorn
- sort by natural order by default, reversed natural order can be specified
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]
Element Summary
Type | Name and 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. |
boolean |
includeSuperProperties Whether to include super properties in the comparison algorithm. |
String[] |
includes Property names to include in the comparison algorithm. |
boolean |
reversed Set to true so that comparator uses reversed natural order. |
Inherited Methods Summary
Methods inherited from class | Name |
---|---|
class Object | wait, wait, wait, equals, toString, hashCode, getClass, notify, notifyAll |
Element Detail
public boolean allNames
Whether to include all fields and/or properties in the comparison algorithm, including those with names that are considered internal. @default false
- Since:
- 2.5.2
public 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). @default true
- Since:
- 2.5.2
public String[] excludes
Property names to exclude in the comparison algorithm. Must not be used if 'includes' is used. @default {}
public 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). @default false
- Since:
- 2.5.2
public 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 {Undefined.STRING}
public boolean reversed
Set to true so that comparator uses reversed natural order. @default false
- Since:
- 2.5.0
© 2003-2020 The Apache Software Foundation
Licensed under the Apache license.
https://docs.groovy-lang.org/2.5.14/html/gapi/groovy/transform/Sortable.html