Question

我想通过java驱动程序在centOS远程服务器上连接我的neo4j数据库。我尝试创建neo4j traverse文件夹并将每个文件插入数据库。代码如下所示：

package neo;

import org.neo4j.driver.v1.*;

import java.io.File;

public class HW {
    Driver driver;
    public HW(String uri, String user, String password) {
        driver = GraphDatabase.driver(uri, AuthTokens.basic(user, password));
    }

    private void addCompany(String name) {
        // Sessions are lightweight and disposable connection wrappers.
        try (Session session = driver.session()) {
            // Wrapping Cypher in an explicit transaction provides atomicity
            // and makes handling errors much easier.
            try (Transaction tx = session.beginTransaction()) {
                tx.run("call apoc.load.json(\"file:///home//ddd//data//shanghai//"+name+"\")yield value as company " + 
                        "create(c:company) " + 
                        "with c,company " + 
                        "unwind company.organizationInformationList as a " + 
                        "set c = a "                            
                        );
                tx.success(); 
            }
        }
    }
    public void close() {
        // Closing a driver immediately shuts down all open connections.
        driver.close();
    }
    public static void main(String... args) {
        File file = new File("/home/ddd/data/shanghai");
        File next[] = file.listFiles();
        HW example = new HW("bolt://202.112.113.71:7687", "neo4j", "rucer2017");
        String CompanyName = "";
        for (int i = 0; i < next.length; i++) {
            CompanyName=next[i].getName();
            example.addCompany(CompanyName);
            System.out.println(CompanyName);
        }
        example.close();
    }
}

代码无法运行。错误是：

org.neo4j.driver.internal.logging.JULogger info
信息: Driver instance org.neo4j.driver.internal.InternalDriver@23ceabc1 created
Exception in thread "main" java.lang.NullPointerException
    at neo.HW.main(HW.java:129)

我花了很多时间修复它并失败了。此外，代码适用于我的本地Windows版Neo4j Desktop.Could任何人都可以帮助我？非常感谢。

Answer 1

它看起来像＆＃34; / home / ddd / data / shanghai＆＃34;不是运行此代码的计算机上的目录的路径。如果该目录不存在，则file.listFiles()将返回null，并且取消引用next.length的尝试将引发NullPointerException。

无法通过java驱动程序在centOS服务器上连接我的neo4j

1 个答案: