Inheritance syntax in Java

Here is the GradStudent class again:

public class GradStudent extends Student {
  private String advisor;

  public GradStudent(String name, String email) {
    super(name, email);
  }

  public void setAdvisor(String advisor) {
      this.advisor = advisor;
  }

  public String getAdvisor() {
      return advisor;
  }
}

Make note of the following:

• To inherit from a class, use the extends keyword as in GradStudent extends Student { ... }.

• The subclass must not redefine the fields/methods of the superclass (unless for overriding which will be discussed later).

• Unlike fields and methods, the constructors of a superclass are not inherited by a subclass. You must define non-default constructors of a subclass. The constructors of the subclass can invoke the constructors of the superclass using the super keyword.

  public GradStudent(String name, String email) {
    super(name, email);
  }
  

  The keyword super is similar to the this keyword but it points to the parent class. It can be used to access fields and methods of the parent class.

  Call to super() must be the first statement in the subclass constructor.

  We could update (or overload) the constructor of GradStudent to take an initial value for advisor:

  public GradStudent(String name, String email, String advisor) {
    super(name, email);
    this.advisor = advisor;
  }