/** * Sorts the childBoundables then divides them into groups of size M, where * M is the node capacity. */ protected List createParentBoundables(List childBoundables, int newLevel) { Assert.isTrue(!childBoundables.isEmpty()); ArrayList parentBoundables = new ArrayList(); parentBoundables.add(createNode(newLevel)); ArrayList sortedChildBoundables = new ArrayList(childBoundables); Collections.sort(sortedChildBoundables, getComparator()); for (Iterator i = sortedChildBoundables.iterator(); i.hasNext(); ) { Boundable childBoundable = (Boundable) i.next(); if (lastNode(parentBoundables).getChildBoundables().size() == getNodeCapacity()) { parentBoundables.add(createNode(newLevel)); } lastNode(parentBoundables).addChildBoundable(childBoundable); } return parentBoundables; }