public void rebuildIndex() {
                
      // Creates a new container same type & size of vertices  
                
      LinkedHashMap<Vec3D, Vertex> newV = new LinkedHashMap<Vec3D, Vertex>(vertices.size());
                
  // Loop through and assign its values to the previously created container
                
      for (Vertex v : vertices.values()) {
                
 newV.put(v, v);
                
 }
                
      // Assigns the duplicate container to the original
                
 vertices = newV;
                
      
                
      // Same process applies for the edges
                
 LinkedHashMap<Line3D, WingedEdge> newE = new LinkedHashMap<Line3D, WingedEdge>(edges.size());
                
 for (WingedEdge e : edges.values()) {
                
 newE.put(e, e);
                
 }
                
 edges = newE;
                
}
               
               

                A LinkedHashMap allows insertion-order iteration over the map. That is, when iterating a 
                LinkedHashMap
                , the elements will be returned in the order in which they were inserted. More here.