Collections.emptyList() instead of null check?

Question

If I have a rarely used collection in some class which may be instantiated many times, I may sometimes resort to the following \"idiom\" in order to save unnecessary object crea

Answer 1

The suggested answers are absolutely correct, just small tip - in Java 8 you can use the new Optional class to handle the case where the list instance is null, in a more functional approach.

For example, something like this:

public static List addElement(List list, String toAdd) {
       List newList = Optional.ofNullable(list).orElse(new ArrayList<>());
       newList.add(toAdd);
       return newList;
}

Following a tip in the comments, it's better to replace new ArrayList<>() with Collections.emptyList() in order to prevent the creation of a new instance of an empty ArrayList

public static List addElement(List list, String toAdd) {
   List newList = Optional.ofNullable(list).orElse(Collections.emptyList());
   newList.add(toAdd);
   return newList;
}