Class design in Java

code_lover · June 5th, 2009, 08:07 AM

I have 2 classes in Java with attributes as follows:

public class Student{
String name;
String address;
String course;
Professor advisor; //here i have used a user-defined type
}

public class Professor{
String name;
String address;
String course;
Student advisee; //here i have used a user-defined type
}

I want to make sure as to whether i am using "Composition" as an OOP technique here or not. If not then what is Composition in OOP, please explain clearly in detail with an example.
Thanks

ciderpunx · November 14th, 2011, 06:43 PM

Quote:

Originally Posted by code_lover

I have 2 classes in Java with attributes as follows:

public class Student{
String name;
String address;
String course;
Professor advisor; //here i have used a user-defined type
}

public class Professor{
String name;
String address;
String course;
Student advisee; //here i have used a user-defined type
}

I want to make sure as to whether i am using "Composition" as an OOP technique here or not. If not then what is Composition in OOP, please explain clearly in detail with an example.
Thanks

Yes you are using composition, in that you are composing your Student Class with a Professor attribute (and vice versa). Composition is a fancy way of saying has-a . You can read that a Student "has-a" Professor. The other common technique you might find is Inheritence. For which you can read "is-a". You could say a Student "is-a" Person (as is a Professor).

HTH