Merging two objects in Java

Question

I have two objects of same type.

Class A {
  String a;
  List b;
  int c;
}

A obj1 = new A();
A obj2 = new A();

obj1 => {a = \"hello\"; b = null; c = 10         


        

Answer 1

In your very special case it looks like you want a new object that takes the real values from both instances. Here is an implementation that will do that. The method should be add to class A so that it can access the fields.

 public A specialMergeWith(A other) {
   A result = new A();

   result.a = (a == null ? other.a : a);
   result.b = (b == null ? other.b : b);
   result.c = (c == DEFAULT_VALUE ? other.c : c);

   return result;
 }