Question

class GroovyClass {
  def aVariable

  void setAVariable(aVariable)
  {
      this.aVariable  = aVariable;
  }
}

My understanding was that we don’t need to specify the type of a variable in a groovy class. But Groovy compiler complains if I declare ‘aVariable’ , why isn’t it considered as a typeless variable with default accessibility ? Should every variable be defined with a def in Groovy both local and class ? Why is it that the function definition doesn’t have to begin with a def ? and when I’m passing in a variable to the setter, it doesn’t need any def in there ?

Answer 1

That code works fine. What do you mean by “Groovy compiler complains”?

You can define that function with a def if you wanted, and it would return aVariable (as that is what the assignment operatop returns), however, it wouldnt be following the standard for Java Beans in that setters should return null

Given that however, I can run:

a = new GroovyClass()
a.aVariable = 3

And it works fine

Edit

Basically, it’s all down to the Groovy parser. The parser expects some sort of list of 1..N keywords defining it’s type or visibility, and then a name for the variable. So the following are all valid:

class OkA {
  def aValue
}

class OkB {
  private aValue
}

class OkC {
  private String aValue
}

But you cannot just (with the current parser) say:

class BadA {
  aValue
}

Thinking about it, there’s no reason I can currently think of for this restriction (as you can declare vars without def in Groovy), but the restriction is there, so you need to type def when defining class attributes.