LinkedListE

LinkedList<E>

java.util

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Java 1.2

cloneable serializable collection

This class implements the List interface in terms of a doubly linked list. In Java 5.0, it also implements the Queue interface and uses its list as a first-in, first-out (FIFO) queue. LinkedList is a generic type, and the type variable E represents the type of the elements of the list. LinkedList supports all optional methods of List , Queue and Collection and allows list elements of any type, including null (in this it differs from most Queue implementations , which prohibit null elements).

Because LinkedList is implemented with a linked list data structure, the get( ) and set( ) methods are substantially less efficient than the same methods for an ArrayList . However, a LinkedList may be more efficient when the add( ) and remove( ) methods are used frequently. The methods of LinkedList are not synchronized . If you are using a LinkedList in a multithreaded environment, you must explicitly synchronize any code that modifies the list or obtain a synchronized wrapper object with Collections.synchronizedList( ) .

In addition to the methods defined by the List interface, LinkedList defines methods to get the first and last elements of the list, to add an element to the beginning or end of the list, and to remove the first or last element of the list. These convenient and efficient methods make LinkedList well-suited for use as a stack or queue. See List and Collection for details on the methods of LinkedList . See also ArrayList .

Figure 16-38. java.util.LinkedList<E>

 public class  LinkedList<E>  extends AbstractSequentialList<E>  implements List<E>, Queue<E>, Cloneable, Serializable {  // Public Constructors  public  LinkedList  ( );        public  LinkedList  (Collection<? extends E>  c  );  // Public Instance Methods  public void  addFirst  (E  o  );        public void  addLast  (E  o  );        public E  getFirst  ( );        public E  getLast  ( );        public E  removeFirst  ( );        public E  removeLast  ( );  // Methods Implementing List  public boolean  add  (E  o  );        public void  add  (int  index  , E  element  );        public boolean  addAll  (Collection<? extends E>  c  );        public boolean  addAll  (int  index  , Collection<? extends E>  c  );        public void  clear  ( );        public boolean  contains  (Object  o  );        public E  get  (int  index  );        public int  indexOf  (Object  o  );        public int  lastIndexOf  (Object  o  );        public ListIterator<E>  listIterator  (int  index  );        public boolean  remove  (Object  o  );        public E  remove  (int  index  );        public E  set  (int  index  , E  element  );        public int  size  ( );        public Object[ ]  toArray  ( );        public <T> T[ ]  toArray  (T[ ]  a  );  // Methods Implementing Queue   5.0  public E  element  ( );  5.0  public boolean  offer  (E  o  );  5.0  public E  peek  ( );  5.0  public E  poll  ( );  5.0  public E  remove  ( );  // Public Methods Overriding Object  public Object  clone  ( );   }