java - Java从上到下读取文件夹中的文件

Question

我正在尝试从文件夹中读取 XML 文件。读取文件后，我提取一个元素并将其写入文本文件中。

文件名看起来像这样

zey_3_20161020-092152_JK6_NO.xml
zey_57_20161020-092152_A_K6.xml
zey_256_20161020-092152_B_A.xml
zey_1000_20161020-092152_B_A.xml

但是当我阅读文件时，我没有得到正确的顺序。 我收到这样的订单:

zey_1000_20161020-092152_B_A.xml
zey_256_20161020-092152_B_A.xml
zey_3_20161020-092152_JK6_NO.xml
zey_57_20161020-092152_A_K6.xml

这是我的代码:

private String rgId;
private NodeList rgIdList;
ArrayList<String> list = new ArrayList<String>();
ArrayList<String> counter = new ArrayList<String>();
String splitFile = null;

public ReadXML() throws ParserConfigurationException, SAXException
{
    try
    {
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        DocumentBuilder builder = factory.newDocumentBuilder();

        File folder = new File("C:/...");
        File[] listFiles = folder.listFiles();

        for (File file : listFiles) {
            if (file.isFile()) {                
                System.out.println(file.getName());

                Document document = builder.parse(file);
                rgIdList = document.getElementsByTagName("id");

                if (rgIdList.getLength() > 0) {
                    rgId = rgIdList.item(0).getTextContent().toString();
                    list.add( rgId);
                }
            }
        }

        FileWriter fw = new FileWriter("C:/....");

        for (String str : list) {
            fw.write(str + "\r\n");
        }
        fw.close();

        System.out.println(list);
    } catch (IOException e) {
        System.out.println(e);
    }
}

public static void main(String[] args) throws IOException, ParserConfigurationException, SAXException {

    new ReadXML();
}

谁能帮忙如何按正确的顺序对文件进行排序？预先感谢您

Answer 1

您的问题与您依赖 File#listFiles() 结果的顺序有关。虽然按照 javadoc 中的说明不能保证顺序:

There is no guarantee that the name strings in the resulting array will appear in any specific order; they are not, in particular, guaranteed to appear in alphabetical order.

如果您想要特定的顺序，您应该使用 Arrays.sort(T[] a, Comparator<? super T> c) 自行对文件进行排序。 .

File[] listFiles = folder.listFiles();
Arrays.sort(listFiles, myComparator);
for (File file : listFiles) {
    ...
}