Question

public class MyClass{
   public String elem1;
   public int elem2;
   public MyType elem3;
.................
}

MyClass object1=new MyClass();
MyClass object2=new MyClass();
object1.elem1=...
object1.elem2=...
...
object2.elem1=...
object2.elem2=null
.....

What I want is something like

object1.merge(object2);

where it will dynamically traverse all members on MyClass and run this on every member

if(object1.elem != object2.elem && object2.elem!=null)
 object1.elem=object2.elem;

Is such a mechanism exist in Java?

Answer 1

use reflection.
go over fields of class. Psuedo:

Field[] fields = aClass.getFields();
for (Field field : fields) {
     // get value
     Object value = field.get(objectInstance);
     // check the values are different, then update 
     field.set(objetInstance, value);    
}

and match the values. if they differ, then update the value.