These examples create a shallow copy of a collection. That is, the new collection contains references to same objects as the source collection; the objects are not cloned. 
    List stuff = Arrays.asList(new String[]{"a", "b"});
    
    // Make a copy of a list
    List list = new ArrayList(stuff);
    List list2 = new LinkedList(list);
    
    // Make a copy of a set
    Set set = new HashSet(stuff);
    Set set2 = new TreeSet(set);
    
    // Make a copy of a map
    Map map = new HashMap();
    // Add key/value pairs ...
    Map map2 = new TreeMap(map);