imagine the following ArrayList in Java:
ArrayList<Integer> u = new ArrayList<Integer>();
I want to know if there is a difference when adding new values either as primitive types or as wrapper-classes:
u.add(new Integer(12));
u.add(12);
Thanks in advance!
There is no difference in add due to auto boxing/unboxing. Actually don't do new Integer(12) but Integer.valueOf(12) since it uses the flighweight pattern and reuses known objects (in the range -128, 127). So no new object would be created.
There is a difference in remove for example.
Since if you intent to call remove(Object) calling remove(5) will call remove(int index) and this perhaps is not what you want.
You should do remove((Integer)5) if you want to remove the number 5 or remove(5) if you want to remove the fifth element.
When you do u.add(12); compiler rewrites it to u.add(Integer.valueOf(12)); which is more efficient than u.add(new Integer(12));
Read more on official tutorial http://docs.oracle.com/javase/tutorial/java/data/autoboxing.html
