Use generic collection interfaces as parameters

Functions that take collection parameters should take the generic parameter. E.g. don’t do this:

public void process(ArrayList list);

do this instead:

public void process(List list);

This avoids putting unnecessary requirements on the parameter. In particular, you can do these:

thing.processList(Collections.EMPTY_LIST);

thing.processList(Collections.singletonList(item));

LinkedList linkedList = getLinkedList();
thing.processList(linkedList);

instead of having to do these:

thing.processList(new ArrayList());

ArrayList list = new ArrayList(1);
list.add(item);
thing.processList(list);

LinkedList linkedList = getLinkedList();
thing.processList(new ArrayList(linkedList));