Question

given a class like

class MyDate extends java.util.Date {
   //add some functionality
}

you create your own Date Object which inherits all functionality.

But if you try to use this functionality like this

MyDate d = MyDate.parse('yyyy','2013')

you will run into the problem that the parse method will return a java.util.Date which can’t be casted to your MyDate.

You can write your own cast through the asType() functionality, but this will not help, because you would have to add it to the Date() class (I know that’s possible, but I would like to avoid it).

Is there another way to solve this Problem?

Answer 1

Groovy’s Date.parse method will return a Date object. If you want it to return your MyDate object, you have to write it (overriding, but still using the super):

@groovy.transform.InheritConstructors class MyDate extends java.util.Date {
  static MyDate parse(String format, String date) {
    new MyDate( Date.parse(format, date).time )
  }

  String formated() {
    format 'dd/MM/yyyy'
  }
}

MyDate d = MyDate.parse('yyyy-MM-dd','2013-09-03')

assert d.formated() == "03/09/2013"

You will also need to inherit the constructors (through this groovy transform) or write your own constructor.