VectorE

Vector<E>

java.util

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Java 1.0

cloneable serializable collection

This class implements an ordered collectionessentially an arrayof objects that can grow or shrink as necessary. In Java 1.2, Vector has been modified to implement the List interface. Unless the synchronized methods of the Vector class are actually needed, ArrayList is preferred in Java 1.2 and later. In Java 5.0 this class has been made generic. The type variable E represents the type of the elements of the vector.

Vector is useful when you need to keep track of a number of objects, but do not know in advance how many there will be. Use setElementAt( ) to set the object at a given index of a Vector . Use elementAt( ) to retrieve the object stored at a specified index. Call add( ) to append an object to the end of the Vector or to insert an object at any specified position. Use removeElementAt( ) to delete the element at a specified index or removeElement( ) to remove a specified object from the vector. size ( ) returns the number of objects currently in the Vector . elements( ) returns an Enumeration that allows you to iterate through those objects. capacity( ) is not the same as size( ) ; it returns the maximum number of objects a Vector can hold before its internal storage must be resized. Vector automatically resizes its internal storage for you, but if you know in advance how many objects a Vector will contain, you can increase its efficiency by pre-allocating this many elements with ensureCapacity( ) .

Figure 16-68. java.util.Vector<E>

 public class  Vector<E>  extends AbstractList<E> implements List<E>,  RandomAccess, Cloneable, Serializable {  // Public Constructors  public  Vector  ( );  1.2  public  Vector  (Collection<? extends E>  c  );        public  Vector  (int  initialCapacity  );        public  Vector  (int  initialCapacity  , int  capacityIncrement  );  // Public Instance Methods  public void  addElement  (E  obj  );  synchronized  public int  capacity  ( );  synchronized  public boolean  contains  (Object  elem  );  Implements:  List      public void  copyInto  (Object[ ]  anArray  );  synchronized  public E  elementAt  (int  index  );  synchronized  public Enumeration<E>  elements  ( );        public void  ensureCapacity  (int  minCapacity  );  synchronized  public E  firstElement  ( );  synchronized  public int  indexOf  (Object  elem  );  Implements:  List      public int  indexOf  (Object  elem  , int  index  );  synchronized  public void  insertElementAt  (E  obj  , int  index  );  synchronized  public boolean  isEmpty  ( );  Implements:  List synchronized default:true      public E  lastElement  ( );  synchronized  public int  lastIndexOf  (Object  elem  );  Implements:  List synchronized      public int  lastIndexOf  (Object  elem  , int  index  );  synchronized  public void  removeAllElements  ( );  synchronized  public boolean  removeElement  (Object  obj  );  synchronized  public void  removeElementAt  (int  index  );  synchronized  public void  setElementAt  (E  obj  , int  index  );  synchronized  public void  setSize  (int  newSize  );  synchronized  public int  size  ( );  Implements:  List synchronized      public void  trimToSize  ( );  synchronized   // Methods Implementing List   1.2  public boolean  add  (E  o  );  synchronized   1.2  public void  add  (int  index  , E  element  );  1.2  public boolean  addAll  (Collection<? extends E>  c  );  synchronized   1.2  public boolean  addAll  (int  index  , Collection<? extends E>  c  );  synchronized   1.2  public void  clear  ( );        public boolean  contains  (Object  elem  );  1.2  public boolean  containsAll  (Collection<?>  c  );  synchronized   1.2  public boolean  equals  (Object  o  );  synchronized   1.2  public E  get  (int  index  );  synchronized   1.2  public int  hashCode  ( );  synchronized  public int  indexOf  (Object  elem  );        public boolean  isEmpty  ( );  synchronized  default:true      public int  lastIndexOf  (Object  elem  );  synchronized   1.2  public boolean  remove  (Object  o  );  1.2  public E  remove  (int  index  );  synchronized   1.2  public boolean  removeAll  (Collection<?>  c  );  synchronized   1.2  public boolean  retainAll  (Collection<?>  c  );  synchronized   1.2  public E  set  (int  index  , E  element  );  synchronized  public int  size  ( );  synchronized   1.2  public List<E>  subList  (int  fromIndex  , int  toIndex  );  synchronized   1.2  public Object[ ]  toArray  ( );  synchronized   1.2  public <T> T[ ]  toArray  (T[ ]  a  );  synchronized   // Protected Methods Overriding AbstractList   1.2  protected void  removeRange  (int  fromIndex  , int  toIndex  );  synchronized   // Public Methods Overriding AbstractCollection  public String  toString  ( );  synchronized   // Public Methods Overriding Object  public Object  clone  ( );  synchronized   // Protected Instance Fields  protected int  capacityIncrement  ;        protected int  elementCount  ;        protected Object[ ]  elementData  ;   } 

Subclasses

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