我正在用Java开发new 4j，我有一个问题。创建节点时，如何验证数据库为空？

下面是我创建节点的代码：

br = new BufferedReader(new FileReader(csvFile));

        while (br.ready()==true) {
            transaction = graphDb.beginTx();
            int cont = 0;//limitador de tuplas por query
            while ((line = br.readLine()) != null && cont < 10000) {

                String[] dado = line.split(cvsSplitBy);

                // inserir comando para criar o nós com a data
                Node no = graphDb.createNode();
                no.setProperty("data", dado[0]);
                no.setProperty("temperatura", dado[1]);
                no.setProperty("latitude", dado[2]);
                no.setProperty("longitude", dado[3]);
                no.setProperty("variação", dado[4]);

                System.out.println(cont);
                cont++;
            }
            transaction.success();
            transaction.close();
        }