[Java] Annotation Type TupleConstructor

Class annotation used to assist in the creation of tuple constructors in classes. Do not use with InheritConstructors.

It allows you to write classes in this shortened form:

 @groovy.transform.TupleConstructor class Customer {
     String first, last
     int age
     Date since
     Collection favItems
 }
 def c1 = new Customer(first:'Tom', last:'Jones', age:21, since:new Date(), favItems:['Books', 'Games'])
 def c2 = new Customer('Tom', 'Jones', 21, new Date(), ['Books', 'Games'])
 def c3 = new Customer('Tom', 'Jones')
 

The @TupleConstructor annotation instructs the compiler to execute an AST transformation which adds the necessary constructor method to your class.

A tuple constructor is created with a parameter for each property (and optionally field and super properties). A default value is provided (using Java's default values) for all parameters in the constructor. Groovy's normal conventions then allows any number of parameters to be left off the end of the parameter list including all of the parameters - giving a no-arg constructor which can be used with the map-style naming conventions.

The order of parameters is given by the properties of any super classes with most super first (if includeSuperProperties is set) followed by the properties of the class followed by the fields of the class (if includeFields is set). Within each grouping the order is as attributes appear within the respective class.

More examples:

 //--------------------------------------------------------------------------
 import groovy.transform.TupleConstructor

 @TupleConstructor()
 class Person {
     String name
     List likes
     private boolean active = false
 }

 def person = new Person('mrhaki', ['Groovy', 'Java'])

 assert person.name == 'mrhaki'
 assert person.likes == ['Groovy', 'Java']

 person = new Person('mrhaki')

 assert person.name == 'mrhaki'
 assert !person.likes
 

 //--------------------------------------------------------------------------
 // includeFields in the constructor creation.
 import groovy.transform.TupleConstructor

 @TupleConstructor(includeFields=true)
 class Person {
     String name
     List likes
     private boolean active = false

     boolean isActivated() { active }
 }

 def person = new Person('mrhaki', ['Groovy', 'Java'], true)

 assert person.name == 'mrhaki'
 assert person.likes == ['Groovy', 'Java']
 assert person.activated
 

 //--------------------------------------------------------------------------
 // use force attribute to force creation of constructor
 // even if we define our own constructors.
 import groovy.transform.TupleConstructor

 @TupleConstructor(force=true)
 class Person {
     String name
     List likes
     private boolean active = false

     Person(boolean active) {
         this.active = active
     }

     boolean isActivated() { active }
 }

 def person = new Person('mrhaki', ['Groovy', 'Java'])

 assert person.name == 'mrhaki'
 assert person.likes == ['Groovy', 'Java']
 assert !person.activated

 person = new Person(true)

 assert person.activated
 

 //--------------------------------------------------------------------------
 // include properties and fields from super class.
 import groovy.transform.TupleConstructor

 @TupleConstructor(includeFields=true)
 class Person {
     String name
     List likes
     private boolean active = false

     boolean isActivated() { active }
 }

 @TupleConstructor(callSuper=true, includeSuperProperties=true, includeSuperFields=true)
 class Student extends Person {
     List courses
 }

 def student = new Student('mrhaki', ['Groovy', 'Java'], true, ['IT'])

 assert student.name == 'mrhaki'
 assert student.likes == ['Groovy', 'Java']
 assert student.activated
 assert student.courses == ['IT']
 

Limitations:

• Groovy's normal map-style naming conventions will not be available if the first property (or field) has type LinkedHashMap or if there is a single Map, AbstractMap or HashMap property (or field)

Authors:

Paul King

Since:

1.8.0