Classes

Constructors

• Can be overloaded.
• Formal parameters do not need types.
• Can be called either with positional or named parameters1

  • Moreover, if you do not create a constructor (i.e., you use the default constructor), you always can the default constructor with named parameters, which map instance properties to actual parameters:

    class PersonWOConstructor {                                  
      String name
      Integer age
    }
    
    // The default constructor for the class above can be invoked in any of the following ways:
    def person4 = new PersonWOConstructor()                      
    def person5 = new PersonWOConstructor(name: 'Marie')         
    def person6 = new PersonWOConstructor(age: 1)                
    def person7 = new PersonWOConstructor(name: 'Marie', age: 2)

    This saves you from having to overload the constructor many times to support the different parameter lists.

References

• http://groovy-lang.org/objectorientation.html
• http://groovy-lang.org/style-guide.html#_initializing_beans_with_named_parameters_and_the_default_constructor

Notes

1. http://groovy-lang.org/objectorientation.html#_constructors

   In Groovy there are two ways to invoke constructors: with positional parameters or named parameters. The former one is like we invoke Java constructors, while the second way allows one to specify the parameter names when invoking the constructor.