vector.java

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    /**
     * Returns the index of the last occurrence of the specified object in
     * this vector.
     *
     * @param   elem   the desired component.
     * @return  the index of the last occurrence of the specified object in
     *          this vector; returns <code>-1</code> if the object is not found.
     * @since   JDK1.0
     */
    public final int lastIndexOf(Object elem) {
	return lastIndexOf(elem, elementCount-1);
    }

    /**
     * Searches backwards for the specified object, starting from the 
     * specified index, and returns an index to it. 
     *
     * @param   elem    the desired component.
     * @param   index   the index to start searching from.
     * @return  the index of the last occurrence of the specified object in this
     *          vector at position less than <code>index</code> in the vector;
     *          <code>-1</code> if the object is not found.
     * @since   JDK1.0
     */
    public final synchronized int lastIndexOf(Object elem, int index) {
	for (int i = index ; i >= 0 ; i--) {
	    if (elem.equals(elementData[i])) {
		return i;
	    }
	}
	return -1;
    }

    /**
     * Returns the component at the specified index.
     *
     * @param      index   an index into this vector.
     * @return     the component at the specified index.
     * @exception  ArrayIndexOutOfBoundsException  if an invalid index was
     *               given.
     * @since      JDK1.0
     */
    public final synchronized Object elementAt(int index) {
	if (index >= elementCount) {
	    throw new ArrayIndexOutOfBoundsException(index + " >= " + elementCount);
	}
	/* Since try/catch is free, except when the exception is thrown,
	   put in this extra try/catch to catch negative indexes and
	   display a more informative error message.  This might not
	   be appropriate, especially if we have a decent debugging
	   environment - JP. */
	try {
	    return elementData[index];
	} catch (ArrayIndexOutOfBoundsException e) {
	    throw new ArrayIndexOutOfBoundsException(index + " < 0");
	}
    }

    /**
     * Returns the first component of this vector.
     *
     * @return     the first component of this vector.
     * @exception  NoSuchElementException  if this vector has no components.
     * @since      JDK1.0
     */
    public final synchronized Object firstElement() {
	if (elementCount == 0) {
	    throw new NoSuchElementException();
	}
	return elementData[0];
    }

    /**
     * Returns the last component of the vector.
     *
     * @return  the last component of the vector, i.e., the component at index
     *          <code>size()&nbsp;-&nbsp;1</code>.
     * @exception  NoSuchElementException  if this vector is empty.
     * @since   JDK1.0
     */
    public final synchronized Object lastElement() {
	if (elementCount == 0) {
	    throw new NoSuchElementException();
	}
	return elementData[elementCount - 1];
    }

    /**
     * Sets the component at the specified <code>index</code> of this 
     * vector to be the specified object. The previous component at that 
     * position is discarded. 
     * <p>
     * The index must be a value greater than or equal to <code>0</code> 
     * and less than the current size of the vector. 
     *
     * @param      obj     what the component is to be set to.
     * @param      index   the specified index.
     * @exception  ArrayIndexOutOfBoundsException  if the index was invalid.
     * @see        java.util.Vector#size()
     * @since      JDK1.0
     */
    public final synchronized void setElementAt(Object obj, int index) {
	if (index >= elementCount) {
	    throw new ArrayIndexOutOfBoundsException(index + " >= " + 
						     elementCount);
	}
	elementData[index] = obj;
    }

    /**
     * Deletes the component at the specified index. Each component in 
     * this vector with an index greater or equal to the specified 
     * <code>index</code> is shifted downward to have an index one 
     * smaller than the value it had previously. 
     * <p>
     * The index must be a value greater than or equal to <code>0</code> 
     * and less than the current size of the vector. 
     *
     * @param      index   the index of the object to remove.
     * @exception  ArrayIndexOutOfBoundsException  if the index was invalid.
     * @see        java.util.Vector#size()
     * @since      JDK1.0
     */
    public final synchronized void removeElementAt(int index) {
	if (index >= elementCount) {
	    throw new ArrayIndexOutOfBoundsException(index + " >= " + 
						     elementCount);
	}
	else if (index < 0) {
	    throw new ArrayIndexOutOfBoundsException(index);
	}
	int j = elementCount - index - 1;
	if (j > 0) {
	    System.arraycopy(elementData, index + 1, elementData, index, j);
	}
	elementCount--;
	elementData[elementCount] = null; /* to let gc do its work */
    }

    /**
     * Inserts the specified object as a component in this vector at the 
     * specified <code>index</code>. Each component in this vector with 
     * an index greater or equal to the specified <code>index</code> is 
     * shifted upward to have an index one greater than the value it had 
     * previously. 
     * <p>
     * The index must be a value greater than or equal to <code>0</code> 
     * and less than or equal to the current size of the vector. 
     *
     * @param      obj     the component to insert.
     * @param      index   where to insert the new component.
     * @exception  ArrayIndexOutOfBoundsException  if the index was invalid.
     * @see        java.util.Vector#size()
     * @since      JDK1.0
     */
    public final synchronized void insertElementAt(Object obj, int index) {
	int newcount = elementCount + 1;
	if (index >= newcount) {
	    throw new ArrayIndexOutOfBoundsException(index
						     + " > " + elementCount);
	}
	if (newcount > elementData.length) {
	    ensureCapacityHelper(newcount);
	}
	System.arraycopy(elementData, index, elementData, index + 1, elementCount - index);
	elementData[index] = obj;
	elementCount++;
    }

    /**
     * Adds the specified component to the end of this vector, 
     * increasing its size by one. The capacity of this vector is 
     * increased if its size becomes greater than its capacity. 
     *
     * @param   obj   the component to be added.
     * @since   JDK1.0
     */
    public final synchronized void addElement(Object obj) {
	int newcount = elementCount + 1;
	if (newcount > elementData.length) {
	    ensureCapacityHelper(newcount);
	}
	elementData[elementCount++] = obj;
    }

    /**
     * Removes the first occurrence of the argument from this vector. If 
     * the object is found in this vector, each component in the vector 
     * with an index greater or equal to the object's index is shifted 
     * downward to have an index one smaller than the value it had previously.
     *
     * @param   obj   the component to be removed.
     * @return  <code>true</code> if the argument was a component of this
     *          vector; <code>false</code> otherwise.
     * @since   JDK1.0
     */
    public final synchronized boolean removeElement(Object obj) {
	int i = indexOf(obj);
	if (i >= 0) {
	    removeElementAt(i);
	    return true;
	}
	return false;
    }

    /**
     * Removes all components from this vector and sets its size to zero.
     *
     * @since   JDK1.0
     */
    public final synchronized void removeAllElements() {
	for (int i = 0; i < elementCount; i++) {
	    elementData[i] = null;
	}
	elementCount = 0;
    }

    /**
     * Returns a clone of this vector.
     *
     * @return  a clone of this vector.
     * @since   JDK1.0
     */
    public synchronized Object clone() {
	try { 
	    Vector v = (Vector)super.clone();
	    v.elementData = new Object[elementCount];
	    System.arraycopy(elementData, 0, v.elementData, 0, elementCount);
	    return v;
	} catch (CloneNotSupportedException e) { 
	    // this shouldn't happen, since we are Cloneable
	    throw new InternalError();
	}
    }

    /**
     * Returns a string representation of this vector. 
     *
     * @return  a string representation of this vector.
     * @since   JDK1.0
     */
    public final synchronized String toString() {
	int max = size() - 1;
	StringBuffer buf = new StringBuffer();
	Enumeration e = elements();
	buf.append("[");

	for (int i = 0 ; i <= max ; i++) {
	    String s = e.nextElement().toString();
	    buf.append(s);
	    if (i < max) {
		buf.append(", ");
	    }
	}
	buf.append("]");
	return buf.toString();
    }
}

final
class VectorEnumerator implements Enumeration {
    Vector vector;
    int count;

    VectorEnumerator(Vector v) {
	vector = v;
	count = 0;
    }

    public boolean hasMoreElements() {
	return count < vector.elementCount;
    }

    public Object nextElement() {
	synchronized (vector) {
	    if (count < vector.elementCount) {
		return vector.elementData[count++];
	    }
	}
	throw new NoSuchElementException("VectorEnumerator");
    }
}