* David McKnight (IBM)          - [204684] CheckExistsJob used for determining if a remote object exists after a query of it's children

		/**

		 * For bug 204684: 

		 * 

		 * Because we don't have an API for ISystemViewElementAdapter.exists()...

		 * This class is used to determine whether an object exists and consequently whether to remove it from the view

		 * after a query comes back with either no children or a SystemMessageObject.  We query the parent to determine

		 * whether the remote object exists - in that case we just leave the message as is in the view.  In the case where

		 * we detect that the object does not exist, we re-populate the parent node with the new children.

		 */

		public class CheckExistenceJob extends UIJob

		{

			private IAdaptable _remoteObject;

			private TreeItem _item;

			public CheckExistenceJob(IAdaptable remoteObject, TreeItem item)

			{

				super("Check existence");

				_remoteObject = remoteObject;

				_item = item;

				setSystem(true);

			}

			public IStatus runInUIThread(IProgressMonitor monitor)

			{				

				ISystemViewElementAdapter adapter = (ISystemViewElementAdapter)_remoteObject.getAdapter(ISystemViewElementAdapter.class);

				TreeItem parentItem = _item.getParentItem();

				IContextObject context = getContextObject(parentItem);

				Object[] children =  adapter.getChildren(context, monitor);

				if (contains(children, _remoteObject))

				{

					// we want to end this so the user sees the error message

				}

				else

				{

					// first need to remove the old items

					TreeItem[] items = parentItem.getItems();

					for (int i = 0; i < items.length; i++) {

						if (items[i].getData() != null) {

							disassociate(items[i]);

							items[i].dispose();

						} else {

							items[i].dispose();

							}

						}

					// we want to propagate the changes to the view

					add(context.getModelObject(), children);

				}

				return Status.OK_STATUS;

			}

			private boolean contains(Object[] children, IAdaptable remoteObject)

			{

				for (int i = 0; i < children.length; i++)

				{

					if (children[i] == remoteObject)

					{

						return true;

					}

				}				

				return false;

			}

		}