private static MyNode getNode(String nodeId,Graph<MyNode, MyLink> g ){
		Iterator nodes=g.getVertices().iterator();
		while(nodes.hasNext()){
		    MyNode myNode=(MyNode)nodes.next();
		    if(nodeId.hashCode()==myNode.id.hashCode()){
		    	return myNode;
		    }
		}
		return null;
	}