Question

I have a doubt considering changing this :

List<String> elements = new ArrayList<String>();

 elements = elementDao.findElementsById(elementId);

to

List<String> elements;

elements = elementDao.findElementsById(elementId);

(I’m using DAO with Hibernate)

Can this cause any errors or exceptions (the fact that i’m not specifying which List implementation should be returned) ?

Answer 1

The first one creates a new arraylist for nothing. The created list is just garbage that has to be collected.

The second one is better, but should be reduced to

List<String> elements = elementDao.findElementsById(elementId);

You seem to be thinking that the assignment operator could be used to fill a list created by the caller. This is not the case. the assignment operator just takes the reference to the list created by the DAO (and which could be any kind of List), and assigns this reference to the variable.