我试图读取java中的xml，但在我的系统中出现了一个错误

Question

您好，我正在编写代码，以便在我的机器上读取XML，它已经在另一台机器上运行良好，但在我的机器上，它在一行代码中出现错误

它读取500600个xml，最后创建一个电子表格 但在错误的第41行，我认为它在函数a中

遵守守则

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package teste;

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

/**
 *
 * @author francielle.garcia
 */
public class Sistema {

    public static void main(String[] args) throws SAXException, IOException, ParserConfigurationException {
        DocumentBuilderFactory fabrica = DocumentBuilderFactory.newInstance();
        DocumentBuilder builder = fabrica.newDocumentBuilder();
        Document xml;
        Element e;        
        File a[];

        File lerxml = new File("C:\\Users\\francielle.garcia\\Desktop\\Ler XML\\localXML.xml");
        xml = builder.parse(lerxml);
        NodeList locais = xml.getElementsByTagName("localXML");
        e = (Element) locais.item(0);
        String local = e.getTextContent();

        File diretorio = new File(local); 
        a = diretorio.listFiles();
        int i;
        for(i = 0; i < a.length; i++){ // linha do erro
            xml = builder.parse(a[i]);

            NodeList payloads = xml.getElementsByTagName("payload");
            e = (Element) payloads.item(0);
            String payload = e.getTextContent();

            NodeList timeStamps = xml.getElementsByTagName("stuMessages");
            e = (Element) timeStamps.item(0);
            String timeStamp = e.getAttribute("timeStamp");


            File arquivo = new File("C:\\Users\\francielle.garcia\\Desktop\\Ler XML\\xml.csv");
            arquivo.createNewFile(); //Caso voce queira criar um novo arquivo a partir de cada formulario use esse comando
            try (FileWriter fw = new FileWriter(arquivo, true)) {
                fw.write(payload + ";" + timeStamp+"\r\n");
            }
        }
        System.out.println("Numero de Linhas Geradas: "+i);


    }

跟踪错误

run:
Exception in thread "main" java.lang.NullPointerException
    at teste.Sistema.main(Sistema.java:41)
C:\Users\francielle.garcia\AppData\Local\NetBeans\Cache\8.2\executor-snippets\run.xml:53: Java returned: 1
FALHA NA CONSTRUÇÃO (tempo total: 0 segundos)

Answer 1

这里

for(i = 0; i < a.length; i++){ // linha do erro

“a.length”正在生成NullPointerException，这是因为此处创建的文件

 File diretorio = new File(local);

具有无效路径