* <code>BoxLayout.X_AXIS</code>,
     * <code>BoxLayout.Y_AXIS</code>,
     * <code>BoxLayout.LINE_AXIS</code> or
     * <code>BoxLayout.PAGE_AXIS</code>
     *
     * @return the axis that was used to lay out components
     *
     * @since 1.6
     */
    public final int getAxis() {
        return this.axis;
    }

    /**
     * Indicates that a child has changed its layout related information,
     * and thus any cached calculations should be flushed.
     * <p>
     * This method is called by AWT when the invalidate method is called
     * on the Container.  Since the invalidate method may be called 
     * asynchronously to the event thread, this method may be called
     * asynchronously.
     *
     * @param target  the affected container
     *
     * @exception AWTError  if the target isn't the container specified to the
     *                      BoxLayout constructor
     */
    public synchronized void invalidateLayout(Container target) {
        checkContainer(target);
        xChildren = null;
        yChildren = null;
        xTotal = null;
        yTotal = null;
    }

    /**
     * Not used by this class.
     *
     * @param name the name of the component
     * @param comp the component
     */
    public void addLayoutComponent(String name, Component comp) {
        invalidateLayout(comp.getParent());
    }

    /**
     * Not used by this class.
     *
     * @param comp the component
     */
    public void removeLayoutComponent(Component comp) {
        invalidateLayout(comp.getParent());
    }

    /**
     * Not used by this class.
     *
     * @param comp the component
     * @param constraints constraints
     */
    public void addLayoutComponent(Component comp, Object constraints) {
        invalidateLayout(comp.getParent());
    }

    /**
     * Returns the preferred dimensions for this layout, given the components
     * in the specified target container.
     *
     * @param target  the container that needs to be laid out
     * @return the dimensions >= 0 && <= Integer.MAX_VALUE
     * @exception AWTError  if the target isn't the container specified to the
     *                      BoxLayout constructor
     * @see Container
     * @see #minimumLayoutSize
     * @see #maximumLayoutSize
     */
    public Dimension preferredLayoutSize(Container target) {
	Dimension size;
	synchronized(this) {
	    checkContainer(target);
	    checkRequests();
	    size = new Dimension(xTotal.preferred, yTotal.preferred);
	}

        Insets insets = target.getInsets();
        size.width = (int) Math.min((long) size.width + (long) insets.left + (long) insets.right, Integer.MAX_VALUE);

        size.height = (int) Math.min((long) size.height + (long) insets.top + (long) insets.bottom, Integer.MAX_VALUE);

        return size;
    }

    /**
     * Returns the minimum dimensions needed to lay out the components
     * contained in the specified target container.
     *
     * @param target  the container that needs to be laid out 
     * @return the dimensions >= 0 && <= Integer.MAX_VALUE
     * @exception AWTError  if the target isn't the container specified to the
     *                      BoxLayout constructor
     * @see #preferredLayoutSize
     * @see #maximumLayoutSize