public void writeIdToVertexMap(String filePath) { try { BufferedWriter bw = new BufferedWriter(new FileWriter(new File(filePath))); for (Entry<Integer, String> entry : nodes.entrySet()) { bw.write(entry.getKey() + " " + entry.getValue() + "\n"); } bw.close(); } catch (Exception ex) { ex.printStackTrace(); System.exit(-1); } }