The type of methods we're designing at present are called instance methods because they are invoked relative to a particular instance of a class. For this reason, an instance method can reference an instance variable directly, without the this qualifier, as long as there is no variable name conflict, for example,

  void bark() {
    System.out.println(barkSound);
  }

In this case, the no-argument version of bark() references the instance variable barkSound directly. As implied by the setBark() definition, however, we could also write bark() as follows:

  void bark() {
    System.out.println(this.barkSound);
  }

Here, there are no other variables within (local to) bark() named barkSound, so these implementations are equivalent.