Basic Inheritance in Java

Question

I'm currently learning and working on an exercise for class. I'm able to get a printout that resembles what I need, but the data isn't populating with test inputs. Name comes back null, Age: 0 and ID: 0.

Here's the scenario:

Assign courseStudent's name with Smith, age with 20, and ID with 9999. Use the printAll member method and a separate println statement to output courseStudents's data. Sample output from the given program:

Name: Smith, Age: 20, ID: 9999

// ===== Code from file PersonData.java =====
public class PersonData {
   private int ageYears;
   private String lastName;

   public void setName(String userName) {
      lastName  = userName;
   }

   public void setAge(int numYears) {
      ageYears = numYears;
   }

   // Other parts omitted

   public void printAll() {
      System.out.print("Name: " + lastName);
      System.out.print(", Age: "  + ageYears);
   }
}
// ===== end =====

// ===== Code from file StudentData.java =====
public class StudentData extends PersonData {
   private int idNum;

   public void setID(int studentId) {
      idNum = studentId;
   }

   public int getID() {
      return idNum;
   }
}
// ===== end =====

// ===== Code from file StudentDerivationFromPerson.java =====
public class StudentDerivationFromPerson {
   public static void main (String [] args) {
      StudentData courseStudent = new StudentData();

      courseStudent.printAll();
      System.out.println(", ID: " + courseStudent.getID());

   }
}
// ===== end =====

I'm sure that I'm overlooking something simple, but I'm not sure what. My code is the just the last few lines:

courseStudent.printAll();
System.out.println(", ID: " + courseStudent.getID());

Answer 1

You need to add set values so you don’t get null and 0 as output. The correct answer is:

courseStudent.setID(9999);
courseStudent.setName(“Smith”);
courseStudent.setAge(20);
courseStudent.printAll();
System.out.print(“, ID: “ + courseStudent.getID());
System.out.println(“”);