删除Java中XML文件的第一行（如果为空）

我从服务器上收到一个包含我的大学时间表的文件，并试图从中提取数据。在某些部门的某些文件中，顶部有一个空行，它是文件的第一行，因此我得到：

[致命错误]课程：2:6:不允许处理指令目标与[xX][mM][lL]匹配

如何检查空白行并在java中删除同一个文件？我无法处理字符串和行，因为XML文件通常在行的末尾没有\n

UPD

UPD xml文件处理：

public String[][] parse(String path)  {
    String[][] table = new String[8][6];

    File data = new File(path);
   // checkForEmptyLines(data);

    DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
    DocumentBuilder dBuilder  = null;
    Document doc = null;

    try {
        dBuilder = dbFactory.newDocumentBuilder();
        doc = dBuilder.parse(data);
    } catch (SAXException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } catch (ParserConfigurationException e) {
        e.printStackTrace();
    }

    doc.getDocumentElement().normalize();
    NodeList nodeList = doc.getElementsByTagName("Data");

    int rowIndex = 0;
    int columnIndex = 0;

    for (int i = 0; i < nodeList.getLength(); ++i) {
        if (i > 7 && !((i - 14) % 7 == 0)) { 
            Node node = nodeList.item(i);
            String line = node.getTextContent().replaceAll("\\t+", " "); 
            line = line.replace("\n", " ");

            if (columnIndex >= 6) {
                columnIndex = 0;
                ++rowIndex;
            }

            table[rowIndex][columnIndex++] = line;
        }
    }

---

XML文件

对此没有快速简单的答案，但可以说您应该了解如何将输入视为流。我已经更新了您的checkforemptylines方法，以基本上推进一个流，直到它到达第一个'，我的同事添加了这段代码，它似乎可以工作。它不仅在开始时检查空字符串，还删除它并将正确的数据写入新文件

这个解决方案似乎很慢，如果可以做任何改进，请告诉我

private static File skipFirstLine(File inputFile) {
    File outputFile = new File("skipped_" + inputFile.getName());

    try (BufferedReader reader = new BufferedReader(new FileReader(inputFile));
         BufferedWriter writer = new BufferedWriter(new FileWriter(outputFile))) {

        String line;
        int count = 0;
        while ((line = reader.readLine()) != null) {
            if (count == 0 && line.equals("")) {
                ++count;
                continue;
            }

            writer.write(line);
            writer.write("\n");
            ++count;
        }
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    return outputFile;
}

---

展示你是如何阅读文件…显示你的代码高兴我怀疑空白线是造成错误。@波希米亚，但如果我不使用这种方法，删除第一个空白行，我把一切都做好了。今天晚些时候，我将附加XML处理。对于您试图解析的XML，我将使用line.trim.isEmpty发布一个示例。如果第一行甚至包含一个空格字符，代码将失败。

//it appeared on knt/151 file, so empty lines in the beginning of the file that caused fatal error
private void checkForEmptyLines(BufferedInputStream fs) throws IOException {
    // Set mark and allow for up to 1024 characters to be read before this mark becomes invalid
    fs.mark(1024);
    int ch;
    while( -1 != (ch = fs.read()) {
        if( '<' == ch ) {
            fs.reset();
            break;
        }
        else {
            fs.mark(1024);
        }
    }
}

public String[][] parse(String path)  {
    String[][] table = new String[8][6];

    File data = new File(path);
    FileInputStream dataStream= new FileInputStream(data);
    BufferedInputStream bufferedDataStream= new BufferedDataStream(dataStream, 1024);
    checkForEmptyLines(bufferedDataStream);

    DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
    DocumentBuilder dBuilder  = null;
    Document doc = null;

    try {
        dBuilder = dbFactory.newDocumentBuilder();
        doc = dBuilder.parse(bufferedDataStream);
    } catch (SAXException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } catch (ParserConfigurationException e) {
        e.printStackTrace();
    }

    doc.getDocumentElement().normalize();
    NodeList nodeList = doc.getElementsByTagName("Data");

    int rowIndex = 0;
    int columnIndex = 0;

    for (int i = 0; i < nodeList.getLength(); ++i) {
        if (i > 7 && !((i - 14) % 7 == 0)) { 
            Node node = nodeList.item(i);
            String line = node.getTextContent().replaceAll("\\t+", " "); 
            line = line.replace("\n", " ");

            if (columnIndex >= 6) {
                columnIndex = 0;
                ++rowIndex;
            }

            table[rowIndex][columnIndex++] = line;
        }
    }

private static File skipFirstLine(File inputFile) {
    File outputFile = new File("skipped_" + inputFile.getName());

    try (BufferedReader reader = new BufferedReader(new FileReader(inputFile));
         BufferedWriter writer = new BufferedWriter(new FileWriter(outputFile))) {

        String line;
        int count = 0;
        while ((line = reader.readLine()) != null) {
            if (count == 0 && line.equals("")) {
                ++count;
                continue;
            }

            writer.write(line);
            writer.write("\n");
            ++count;
        }
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    return outputFile;
}