vector.java

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    System.arraycopy(elementData, index, elementData, index + 1,
                     elementCount - index);
    elementCount++;
    elementData[index] = obj;
  }

  /**
   * Adds an element to the Vector at the end of the Vector.  The vector
   * is increased by ensureCapacity(size() + 1) if needed.
   *
   * @param obj the object to add to the Vector
   */
  public synchronized void addElement(Object obj)
  {
    if (elementCount == elementData.length)
      ensureCapacity(elementCount + 1);
    modCount++;
    elementData[elementCount++] = obj;
  }

  /**
   * Removes the first (the lowestindex) occurance of the given object from
   * the Vector. If such a remove was performed (the object was found), true
   * is returned. If there was no such object, false is returned.
   *
   * @param obj the object to remove from the Vector
   * @return true if the Object was in the Vector, false otherwise
   * @see #remove(Object)
   */
  public synchronized boolean removeElement(Object obj)
  {
    int idx = indexOf(obj, 0);
    if (idx >= 0)
      {
        remove(idx);
        return true;
      }
    return false;
  }

  /**
   * Removes all elements from the Vector.  Note that this does not
   * resize the internal data array.
   *
   * @see #clear()
   */
  public synchronized void removeAllElements()
  {
    if (elementCount == 0)
      return;

    modCount++;
    Arrays.fill(elementData, 0, elementCount, null);
    elementCount = 0;
  }

  /**
   * Creates a new Vector with the same contents as this one. The clone is
   * shallow; elements are not cloned.
   *
   * @return the clone of this vector
   */
  public synchronized Object clone()
  {
    try
      {
        Vector clone = (Vector) super.clone();
        clone.elementData = (Object[]) elementData.clone();
        return clone;
      }
    catch (CloneNotSupportedException ex)
      {
        // Impossible to get here.
        throw new InternalError(ex.toString());
      }
  }

  /**
   * Returns an Object array with the contents of this Vector, in the order
   * they are stored within this Vector.  Note that the Object array returned
   * is not the internal data array, and that it holds only the elements
   * within the Vector.  This is similar to creating a new Object[] with the
   * size of this Vector, then calling Vector.copyInto(yourArray).
   *
   * @return an Object[] containing the contents of this Vector in order
   * @since 1.2
   */
  public synchronized Object[] toArray()
  {
    Object[] newArray = new Object[elementCount];
    copyInto(newArray);
    return newArray;
  }

  /**
   * Returns an array containing the contents of this Vector.
   * If the provided array is large enough, the contents are copied
   * into that array, and a null is placed in the position size().
   * In this manner, you can obtain the size of a Vector by the position
   * of the null element, if you know the vector does not itself contain
   * null entries.  If the array is not large enough, reflection is used
   * to create a bigger one of the same runtime type.
   *
   * @param a an array to copy the Vector into if large enough
   * @return an array with the contents of this Vector in order
   * @throws ArrayStoreException the runtime type of the provided array
   *         cannot hold the elements of the Vector
   * @throws NullPointerException if <code>a</code> is null
   * @since 1.2
   */
  public synchronized Object[] toArray(Object[] a)
  {
    if (a.length < elementCount)
      a = (Object[]) Array.newInstance(a.getClass().getComponentType(),
                                       elementCount);
    else if (a.length > elementCount)
      a[elementCount] = null;
    System.arraycopy(elementData, 0, a, 0, elementCount);
    return a;
  }

  /**
   * Returns the element at position <code>index</code>.
   *
   * @param index the position from which an element will be retrieved
   * @return the element at that position
   * @throws ArrayIndexOutOfBoundsException index &lt; 0 || index &gt;= size()
   * @since 1.2
   */
  public Object get(int index)
  {
    return elementAt(index);
  }

  /**
   * Puts <code>element</code> into the Vector at position <code>index</code>
   * and returns the Object that previously occupied that position.
   *
   * @param index the index within the Vector to place the Object
   * @param element the Object to store in the Vector
   * @return the previous object at the specified index
   * @throws ArrayIndexOutOfBoundsException index &lt; 0 || index &gt;= size()
   * @since 1.2
   */
  public synchronized Object set(int index, Object element)
  {
    checkBoundExclusive(index);
    Object temp = elementData[index];
    elementData[index] = element;
    return temp;
  }

  /**
   * Adds an object to the Vector.
   *
   * @param o the element to add to the Vector
   * @return true, as specified by List
   * @since 1.2
   */
  public boolean add(Object o)
  {
    addElement(o);
    return true;
  }

  /**
   * Removes the given Object from the Vector.  If it exists, true
   * is returned, if not, false is returned.
   *
   * @param o the object to remove from the Vector
   * @return true if the Object existed in the Vector, false otherwise
   * @since 1.2
   */
  public boolean remove(Object o)
  {
    return removeElement(o);
  }

  /**
   * Adds an object at the specified index.  Elements at or above
   * index are shifted up one position.
   *
   * @param index the index at which to add the element
   * @param element the element to add to the Vector
   * @throws ArrayIndexOutOfBoundsException index &lt; 0 || index &gt; size()
   * @since 1.2
   */
  public void add(int index, Object element)
  {
    insertElementAt(element, index);
  }

  /**
   * Removes the element at the specified index, and returns it.
   *
   * @param index the position from which to remove the element
   * @return the object removed
   * @throws ArrayIndexOutOfBoundsException index &lt; 0 || index &gt;= size()
   * @since 1.2
   */
  public synchronized Object remove(int index)
  {
    checkBoundExclusive(index);
    Object temp = elementData[index];
    modCount++;
    elementCount--;
    if (index < elementCount)
      System.arraycopy(elementData, index + 1, elementData, index,
                       elementCount - index);
    elementData[elementCount] = null;
    return temp;
  }

  /**
   * Clears all elements in the Vector and sets its size to 0.
   */
  public void clear()
  {
    removeAllElements();
  }

  /**
   * Returns true if this Vector contains all the elements in c.
   *
   * @param c the collection to compare to
   * @return true if this vector contains all elements of c
   * @throws NullPointerException if c is null
   * @since 1.2
   */
  public synchronized boolean containsAll(Collection c)
  {
    // Here just for the sychronization.
    return super.containsAll(c);
  }

  /**
   * Appends all elements of the given collection to the end of this Vector.
   * Behavior is undefined if the collection is modified during this operation
   * (for example, if this == c).
   *
   * @param c the collection to append
   * @return true if this vector changed, in other words c was not empty
   * @throws NullPointerException if c is null
   * @since 1.2
   */
  public synchronized boolean addAll(Collection c)
  {
    return addAll(elementCount, c);
  }

  /**
   * Remove from this vector all elements contained in the given collection.
   *
   * @param c the collection to filter out
   * @return true if this vector changed
   * @throws NullPointerException if c is null
   * @since 1.2
   */
  public synchronized boolean removeAll(Collection c)
  {
    if (c == null)
      throw new NullPointerException();

    int i;
    int j;
    for (i = 0; i < elementCount; i++)
      if (c.contains(elementData[i]))
        break;
    if (i == elementCount)
      return false;

    modCount++;
    for (j = i++; i < elementCount; i++)
      if (! c.contains(elementData[i]))
        elementData[j++] = elementData[i];
    elementCount -= i - j;
    return true;
  }

  /**
   * Retain in this vector only the elements contained in the given collection.
   *
   * @param c the collection to filter by
   * @return true if this vector changed
   * @throws NullPointerException if c is null
   * @since 1.2
   */
  public synchronized boolean retainAll(Collection c)
  {
    if (c == null)
      throw new NullPointerException();

    int i;
    int j;
    for (i = 0; i < elementCount; i++)
      if (! c.contains(elementData[i]))
        break;
    if (i == elementCount)
      return false;

    modCount++;
    for (j = i++; i < elementCount; i++)
      if (c.contains(elementData[i]))
        elementData[j++] = elementData[i];
    elementCount -= i - j;
    return true;
  }

  /**
   * Inserts all elements of the given collection at the given index of
   * this Vector. Behavior is undefined if the collection is modified during
   * this operation (for example, if this == c).
   *
   * @param c the collection to append
   * @return true if this vector changed, in other words c was not empty
   * @throws NullPointerException if c is null
   * @throws ArrayIndexOutOfBoundsException index &lt; 0 || index &gt; size()
   * @since 1.2
   */
  public synchronized boolean addAll(int index, Collection c)
  {
    checkBoundInclusive(index);
    Iterator itr = c.iterator();
    int csize = c.size();

    modCount++;
    ensureCapacity(elementCount + csize);
    int end = index + csize;
    if (elementCount > 0 && index != elementCount)
      System.arraycopy(elementData, index,
		       elementData, end, elementCount - index);
    elementCount += csize;
    for ( ; index < end; index++)
      elementData[index] = itr.next();
    return (csize > 0);
  }

  /**
   * Compares this to the given object.
   *
   * @param o the object to compare to
   * @return true if the two are equal
   * @since 1.2
   */
  public synchronized boolean equals(Object o)
  {
    // Here just for the sychronization.
    return super.equals(o);
  }

  /**
   * Computes the hashcode of this object.
   *
   * @return the hashcode
   * @since 1.2
   */
  public synchronized int hashCode()
  {
    // Here just for the sychronization.
    return super.hashCode();
  }

  /**
   * Returns a string representation of this Vector in the form
   * "[element0, element1, ... elementN]".
   *
   * @return the String representation of this Vector
   */
  public synchronized String toString()
  {
    // Here just for the sychronization.
    return super.toString();
  }

  /**
   * Obtain a List view of a subsection of this list, from fromIndex
   * (inclusive) to toIndex (exclusive). If the two indices are equal, the
   * sublist is empty. The returned list is modifiable, and changes in one
   * reflect in the other. If this list is structurally modified in
   * any way other than through the returned list, the result of any subsequent
   * operations on the returned list is undefined.
   * <p>
   *
   * @param fromIndex the index that the returned list should start from
   *        (inclusive)
   * @param toIndex the index that the returned list should go to (exclusive)
   * @return a List backed by a subsection of this vector
   * @throws IndexOutOfBoundsException if fromIndex &lt; 0
   *         || toIndex &gt; size()
   * @throws IllegalArgumentException if fromIndex &gt; toIndex
   * @see ConcurrentModificationException
   * @since 1.2
   */
  public synchronized List subList(int fromIndex, int toIndex)
  {
    List sub = super.subList(fromIndex, toIndex);
    // We must specify the correct object to synchronize upon, hence the
    // use of a non-public API
    return new Collections.SynchronizedList(this, sub);
  }

  /**
   * Removes a range of elements from this list.
   * Does nothing when toIndex is equal to fromIndex.
   *
   * @param fromIndex the index to start deleting from (inclusive)
   * @param toIndex the index to delete up to (exclusive)
   * @throws IndexOutOfBoundsException if fromIndex &gt; toIndex
   */
  // This does not need to be synchronized, because it is only called through
  // clear() of a sublist, and clear() had already synchronized.
  protected void removeRange(int fromIndex, int toIndex)
  {
    int change = toIndex - fromIndex;
    if (change > 0)
      {
        modCount++;
        System.arraycopy(elementData, toIndex, elementData, fromIndex,
                         elementCount - toIndex);
        int save = elementCount;
        elementCount -= change;
        Arrays.fill(elementData, elementCount, save, null);
      }
    else if (change < 0)
      throw new IndexOutOfBoundsException();
  }

  /**
   * Checks that the index is in the range of possible elements (inclusive).
   *
   * @param index the index to check
   * @throws ArrayIndexOutOfBoundsException if index &gt; size
   */
  private void checkBoundInclusive(int index)
  {
    // Implementation note: we do not check for negative ranges here, since
    // use of a negative index will cause an ArrayIndexOutOfBoundsException
    // with no effort on our part.
    if (index > elementCount)
      throw new ArrayIndexOutOfBoundsException(index + " > " + elementCount);
  }

  /**
   * Checks that the index is in the range of existing elements (exclusive).
   *
   * @param index the index to check
   * @throws ArrayIndexOutOfBoundsException if index &gt;= size
   */
  private void checkBoundExclusive(int index)
  {
    // Implementation note: we do not check for negative ranges here, since
    // use of a negative index will cause an ArrayIndexOutOfBoundsException
    // with no effort on our part.
    if (index >= elementCount)
      throw new ArrayIndexOutOfBoundsException(index + " >= " + elementCount);
  }
}