// updates nodes in given TreeSet between node.getPosition() and position
private void updatePositionNodeSet(PositionNode node, int position, TreeSet<PositionNode> set) {
if (set.size() == 0) {
return;
}
int oldPos = node.getPosition();
int diff = position - oldPos;
SortedSet<PositionNode> posNodes;
boolean containsNode = false;
if (diff == 0) {
return;
}
// remove node before decrementing or incrementing to prevent overwriting
if (set.contains(node)) {
containsNode = true;
set.remove(node);
}
if (diff > 0) {
posNodes = set.subSet(node, false, new PositionNode(position), true);
List<PositionNode> pNodeList = new ArrayList<>();
for (PositionNode pos : posNodes) {
pNodeList.add(pos);
}
// decrement posNodes
for (PositionNode pos : pNodeList) {
int p = pos.getPosition() - 1;
updatePositionNode(pos, p, set);
}
} else {
posNodes = set.subSet(new PositionNode(position), true, node, false);
// create list to iterate in reverse order
List<PositionNode> pNodeList = new ArrayList<>();
for (PositionNode pos : posNodes) {
pNodeList.add(pos);
}
// increment elements of TreeSet in reverse order so
// that no collisions occur - PositionNodes are incremented
// into slot created by removing node
for (int i = pNodeList.size() - 1; i >= 0; i--) {
PositionNode pNode = pNodeList.get(i);
int p = pNode.getPosition() + 1;
updatePositionNode(pNode, p, set);
}
}
if (containsNode) {
node.setPosition(position);
set.add(node);
}
}
// works only if moving node to final position does not move it across
// another node in set
private void updatePositionNode(PositionNode node, int position, TreeSet<PositionNode> set) {
set.remove(node);
node.setPosition(position);
set.add(node);
}
