@Retention(value=RUNTIME)
@Target(value=TYPE)
public @interface Sortable
@Sortable class Person {
String first
String last
Integer born
}
The generated Groovy class will:
Comparable interfacecompareTo 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)Comparator methods named comparatorByFirst,
comparatorByLast and comparatorByBornComparable 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']