Delving Further into Object-Oriented Concepts - Beginning Java Programming: The Object-Oriented Approach - page 242

Remember, your Employee class should extend this Person class. Also, the variables manager and
employeeID are added to the Employee class, since not all Person instances will have a manager ,
but all Employee instances will.
public class Employee extends Person {
private Employee manager;
private int id;
public Employee(String name, Employee manager, int empID) {
super(name);
this.setManager(manager);
this.setEmployeeID(empID);
}
public Employee getManager() {
return manager;
}
public void setManager(Employee manager) {
this.manager = manager;
}
public int getEmployeeID() {
return id;
}
private void setEmployeeID(int employeeID) {
this.id = employeeID;
}
}
Notice how the super keyword is used in the first statement of the constructor. This means that the
Employee should be constructed as a Person is constructed, then specialized with the manager and id .
Similar to specializing a subclass constructor by first calling the super constructor, you can also spe-
cialize methods by first calling a super method. Suppose you want to add a displayName() method
to the Employee class that allows you to format their name badge.
public String displayName(){
return "Employee: " + super.getName();
}
In the displayName() method, you have a specialized method for Employee that calls the method
of the superclass to get some of the necessary information.
You can also access superclass variables using the super keyword. Suppose in your Person class
you have an int variable called id that you use to uniquely identify people in your database. But
you still have the int variable id in the Employee class that you use to store their employee ID. You
might use the following method to return a String with both id numbers:
public String displayIdentification() {