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

There is a dynamic solution to merge any two objects which require Reflection and Recursion.

public  T merge(T local, T remote, ArrayList listOfClass)
        throws IllegalAccessException, InstantiationException {
    Class clazz = local.getClass();
    Object merged = clazz.newInstance();
    for (Field field : clazz.getDeclaredFields()) {
        field.setAccessible(true);
        Object localValue = field.get(local);
        Object remoteValue = field.get(remote);
        if (localValue != null) {
            if (listOfClass.contains(localValue.getClass().getSimpleName())) {
                field.set(merged, this.merge(localValue, remoteValue, listOfClass));
            } else {
                field.set(merged, (remoteValue != null) ? remoteValue : localValue);
            }
        } else if (remoteValue != null) {
            field.set(merged, remoteValue);
        }
    }
    return (T) merged;
}

Variable Description:

• local: The object on to which the other will be merged
• remote: The object which will be merged to the local object
• listOfClass: The ArrayList of custom classes in the given object

The function returns a merged object which is good to go.

Kudos! :)