SpatialReference spatialReference;
QuadTree quadTree;
QuadTreeIterator quadTreeIter;
private void buildQuadTree(){
quadTree = new QuadTree(new Envelope2D(-180, -90, 180, 90), 8);
Envelope envelope = new Envelope();
for (int i=0;i<featureClass.features.length;i++){
featureClass.features[i].geometry.queryEnvelope(envelope);
quadTree.insert(i, new Envelope2D(envelope.getXMin(), envelope.getYMin(), envelope.getXMax(), envelope.getYMax()));