AbstractListE

AbstractList<E>

java.util

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Java 1.2

collection

This abstract class is a partial implementation of the List interface that makes it easy to define custom List implementations based on random-access list elements (such as objects stored in an array). If you want to base a List implementation on a sequential-access data model (such as a linked list), subclass AbstractSequentialList instead.

To create an unmodifiable List , simply subclass AbstractList and override the (inherited) size ( ) and get( ) methods . To create a modifiable list, you must also override set( ) and, optionally , add( ) and remove( ) . These three methods are optional, so unless you override them, they simply throw an UnsupportedOperationException . All other methods of the List interface are implemented in terms of size( ) , get( ) , set( ) , add( ) , and remove( ) . In some cases, you may want to override these other methods to improve performance. By convention, all List implementations should define two constructors: one that accepts no arguments and another that accepts a Collection of initial elements for the list.

Figure 16-2. java.util.AbstractList<E>

 public abstract class  AbstractList<E>  extends AbstractCollection<E> implements List<E> {  // Protected Constructors  protected  AbstractList  ( );  // Methods Implementing List  public boolean  add  (E  o  );        public void  add  (int  index  , E  element  );        public boolean  addAll  (int  index  , Collection<? extends E>  c  );        public void  clear  ( );        public boolean  equals  (Object  o  );        public abstract E  get  (int  index  );        public int  hashCode  ( );        public int  indexOf  (Object  o  );        public Iterator<E>  iterator  ( );        public int  lastIndexOf  (Object  o  );        public ListIterator<E>  listIterator  ( );        public ListIterator<E>  listIterator  (int  index  );        public E  remove  (int  index  );        public E  set  (int  index  , E  element  );        public List<E>  subList  (int  fromIndex  , int  toIndex  );  // Protected Instance Methods  protected void  removeRange  (int  fromIndex  , int  toIndex  );  // Protected Instance Fields  protected transient int  modCount  ;   } 

Subclasses

AbstractSequentialList , ArrayList , Vector