not synchronized TreeSet TreeMap LinkedList HashSet HashMap ArrayList LinkedHashMap LinkedHashSet synchronized Hashtable Vector public class ArrayDeque<E> extends AbstractCollection<E> implements Deque<E>, Cloneable, Serializable Resizable-array implementation of the Deque interface. Array deques have no capacity restrictions; they grow as necessary to support usage. They are not thread-safe; in the absence of external synchronization, they do not support concurrent access by multiple threads. Null elements are prohibited. This class is likely to be faster than Stack when used as a stack, and faster than LinkedList when used as a queue. public class ArrayList<E> extends AbstractList<E> implements List<E>, RandomAccess, Cloneable, Serializable Resizable-array implementation of the List interface. Implements all optional list operations, and permits all elements, including null. In addition to implementing the List interface,