Question

I am new to Java and am struggling with associations. I have a class

public class A{
  private string name;

  public string get_name() {
    return name;
  }

  public void set_name(string name) {
    name = name;
  }
}

I have an association with another class B as association A -> B. It is one to one association. Now what I would like to do is to create another class C which is of type class A. So in other words, C is the same class as A but with different name. But there is 1 to many association between A and C. I would appreciate any help!

Answer 1

If C is A with a different name why not just initialize an instance of A and name it C?

A c = new A();
c.set_name("Bob");

Alternatively, if Cis going to change over time but be reliant on A make C extend A

public class C extends A{

}

However, I would be wary of using the above as its generally a bad idea to make a superclass concrete (What if A changes down the line and you don’t want C to inherit those changes?). So, make A an interface/abstract class and make both C and Aconcrete implement it.

Something like the following would be good…

abstract class A{
  protected String name; //Protected so that subclasses can call it

  public String get_name() {
     return name;
  }

  public void set_name(String name) {
    this.name = name;
  }

}

class C extends A{


}

class Aconcrete extends A{

}