Ordering Collections (SAP Library - Enterprise Knowledge Management)

Ordering Collections

By default, the resources in a collection have an arbitrary sequence and no special order. If you want to explicitly specify an order, you can:

● Set the ordering of the collection to manual with the setOrderType()method offered by the ICollection interface

● Use the methods of IReorderList to change the sequence of the resources in the collection

The UML diagram shows the main classes and interfaces involved in the ordering of collections.

This graphic is explained in the accompanying text

Interfaces and Classes

Interface or Class	Purpose
IReorderList	Offers methods to reposition resources. The methods require an IPositioning object that stores the new position of a resource.
IPositioning	Stores the name of the resource that is to be repositioned and references the IPosition object that contains the target position.
`IPosition`,	A container for the target position of a resource. The target position is specified using the definitions provided by `enum.OrderPosition`: ● OrderPosition.FIRST The first resource ● OrderPosition.LAST The last resource ● OrderPosition.BEFORE The predecessor of another resource ● OrderPosition.AFTER The successor of another resource

Setting Ordering for a Collection

To enable the resources in a collection to be ordered, you first set the ordering of the collection to manual:

ICollection coll = …;

coll.setOrderType(OrderType.MANUAL);

If a collection does not support ordering, the exception NotSupportedException is thrown.

Repositioning Resources

Once ordering is set to manual, you can reposition the resources as required. The code extract shows how a collection with the children 1st, 2nd, 3rd, 4th (ordered in this sequence) is reordered to 4th, 3rd, 1st, 2nd. The ReorderList.add()method repositions the resources according to the information provided by the Positioning object that is passed to the method as an argument. The IPositioning object contains the name of the resource involved and its new position.

Note

When the new position is relative, for example, OrderPosition.BEFORE, then it is specified in relationship to another resource. For example, the following code line specifies that the resource 3rd must be moved behind the resource 4th :
reordering.add(new Positioning(″3rd″, new Position(″4th″, OrderPosition.AFTER)))

IReorderList reordering = new ReorderList();

reordering.add(

  new Positioning(″4th″, new Position.createFirstPosition())

);

reordering.add(

  new Positioning(″1st″, new Position.createLastPosition())

);

reordering.add(

  new Positioning(″2nd″, new Position(″1st″, OrderPosition.BEFORE))

);

reordering.add(

  new Positioning(″3rd″, new Position(″4th″, OrderPosition.AFTER))

);

orderedCollection.reorder(reordering);