Question

你好，我正在编写代码以在我的计算机上读取xmls，它已经可以在另一台计算机上完美运行，但是在我的计算机上，它在一行代码中给出了错误

读取500、600 xml，最后创建一个电子表格但是在错误的第41行，我认为它在函数a.length

中

遵循代码

/*
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 * 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);


    }

遵循错误

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

此处

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

“ a.length”正在产生NullPointerException，这就是因为在此处创建的文件

 File diretorio = new File(local);

路径无效

我正在尝试在Java中读取xml，但系统上却出现错误

1 个答案: