getter / setter question

[mark geroso]

Hi.
I'm supposed to create 3 classes ... Course, Instructor and CourseInstructor. Classes Course and Instructor have their own specific instance variables. Class CourseInstructor uses one variable from Course and one variable from Instructor.

  
class Instructor {
String insName;
int insID;
String insDisc;

public int insID(){
return insID;
}

public void setinsID(int newID){
insID = newID;
}

}
 
class Course{
String courseName;
int courseID;
}
 
public int courseID(){
return courseID;
}

public void setcourseID(int newID){
courseID = newID;
}
 

class CourseInstructor{
int courseID;
int insID;
}
 
        public int insID(){
return insID;
}

public void setinsID(int newID){
insID = newID;
}
 
public int courseID(){
return courseID;
}

public void setcourseID(int newID){
courseID = newID;
}
 

Will that work? I just used the same setter and getter methods from the other 2 classes. Is there a more elegant way to do it?
I just need to populate the variables and then I can manipulate it in a main class or something.
Thanks

[Deepak Bala]

Your current code will not compile. It looks like you closed the class right after you defined your instance variables and then you are defining funtions after this that dont go into a class body. Also... ClassInstructor does not extend from any class so you are not using the instance variables of any other class. I suggest you extend from both classes. That way you dont have to redefine variables or methods (assuming you dont want to override getters and setters for a more specific operation).

[Garrett Rowe]

I suggest you extend from both classes...

Not in Java (no multiple inheritance here). Although when you consider the is-a and has-a relationships, intuitively a CourseInstructor is-a(n) Instructor, and has-a Course. So the CourseInstructor class might look like this.

public class CouseInstructor extends Instructor
{
   private Course course;
 
   public CourseInstructor(){//...}
}

[Garrett Rowe]

<piggyback>
Or perhaps even...

interface Instructor
{
   int getInsID();
   void setinsID(int newID);
}
 
abstract class AbstractInstructor
{
   String insName;
   int insID;
 
   public int insID()
   {
      return insID;
   }

   public void setinsID(int newID)
   {
      insID = newID;
   }
}
 
public class CourseInstructor extends AbstractInstructor
        implements Instructor
{
   private Course course;
 
   //...
}

</piggyback>
[ October 13, 2006: Message edited by: Garrett Rowe ]

[Deepak Bala]

I suggest you extend from both classes...

Whoops !!! my bad. Wrongly worded. This is what I meant...

CourseInstructor -> Instructor -> Course

Of course this is just to have access to the getters and setters. CourseInstructor is a Instructor and has a course makes more sense.
[ October 13, 2006: Message edited by: John Meyers ]

[mark geroso]

Thanks for the replies. I can't use inheritance and abstracts and interfaces because the prof has only covered (lesson 1) Intro to Java and (lesson 2) Classes and Objects.
The problem was: Make 3 classes course, ins.... they all have their specific variables... (without using inheritance, is there still a way I can just use the setter/getter for course and instructor for courseinstructor?) Then write a main method, populate the variables and given the course code, display the instructor name.
Here's the code I ended up writing, mind you, it's pretty long because of all the setters and getters I had to use. It works, but it's pretty clunky. So, is there anyway to shorten this? And/or improve this, without using inheritance, abstract or interfaces?

Thanks.

[size=1]
class Instructor {
String insName;
int insID;
String insDisc;

Instructor(String insName, int insID, String insDisc){
this.insName = insName;
this.insID = insID;
this.insDisc = insDisc;
}

public String getInsDisc() {
return insDisc;
}
 
public void setInsDisc(String insDisc) {
this.insDisc = insDisc;
}
 
public int getInsID() {
return insID;
}
 
public void setInsID(int insID) {
this.insID = insID;
}
 
public String getInsName() {
return insName;
}
 
public void setInsName(String insName) {
this.insName = insName;
}

}
 
class Course{
String courseName;
int courseID;

Course(String courseName, int courseID){
this.courseName = courseName;
this.courseID = courseID;
}
 
public int courseID(){
return courseID;
}

public int getCourseID() {
return courseID;
}
 
public void setCourseID(int courseID) {
this.courseID = courseID;
}
 
public String getCourseName() {
return courseName;
}
 
public void setCourseName(String courseName) {
this.courseName = courseName;
}
}
 
class CourseInstructor{
int courseID;
int insID;

CourseInstructor(int courseID, int insID){
this.courseID = courseID;
this.insID = insID;
}

public int getCourseID() {
return courseID;
}
public void setCourseID(int courseID) {
this.courseID = courseID;
}
public int getInsID() {
return insID;
}
public void setInsID(int insID) {
this.insID = insID;
}
}
 
public class InstructorDetails{
public static void main( String args []){
Course courseDetails [] = new Course [2] ;
Instructor insDetails [] = new Instructor [2] ;
CourseInstructor a []  = new CourseInstructor [2] ;

courseDetails[0] = new Course("Core Java", 123);
courseDetails[1] = new Course("Literature", 127);
        
insDetails[0] = new Instructor ("Bruce Eckel", 1111, "Programming");
insDetails[1] = new Instructor ("William Shakespeare", 2222, "English");

a[0]  = new CourseInstructor (123, 1111);
a[1]  = new CourseInstructor (127, 2222);

for(int k = 120; k < 130; k++){
for (int i = 0; i < 2; i++){
if (a[i].courseID == k)
if (a[i].insID == insDetails[i].insID)
System.out.println("Instructor: " +insDetails[i].insName);

}
}
}
}
[/size]