在删除Java中的列后，如何更换CSV文件

发布于 2025-02-13 23:00:44 字数 362 浏览 3 评论 0原文

我是Java的新手。我成功地从本地文件位置读取了我的CSV文件，并且能够确定为我的要求删除哪个列。但是，我无法删除所需的列，并将文件写入我的本地文件夹。有没有办法解决此问题？我使用以下代码：

    CSVReader reader = new CSVReader(new FileReader(fileName));
    String [] nextLine;
    while ((nextLine = reader.readNext()) != null) {
        System.out.println(nextLine[15]);
    }

我要做的就是删除具有索引15的列，并将文件写入我的本地文件夹中的CSV文件。

原文

I am new to Java. I was successfully able to read my CSV file from my local file location and was able to identify which column needed to be deleted for my requirements. However, I was not able to delete the required column and write the file into my local folder. Is there a way to resolve this issue? I have used the following code:

    CSVReader reader = new CSVReader(new FileReader(fileName));
    String [] nextLine;
    while ((nextLine = reader.readNext()) != null) {
        System.out.println(nextLine[15]);
    }

All I would like to do is to remove the column having index 15 and write the file as a CSV file in my local folder.

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長街聽風 2025-02-20 23:00:44

我假设您正在使用OpenCSV库。

为了使您的代码工作，您必须解决2个问题：

您需要一个作者将修改后的CSV写入。 OpenCSV为此提供了CSVWriter类。
您需要将行（当前是字符串数组）转换为列表以删除元素，然后将其转换回数组以匹配csvwriter.writeenext方法所期望的内容。

这是一些执行此操作的代码：

CSVReader reader = new CSVReader(new FileReader(fileName));
CSVWriter writer = new CSVWriter(new FileWriter(outFileName));
String[] origLine;
while ((origLine = reader.readNext()) != null) {
    List<String> lineList = new ArrayList<>(Arrays.asList(origLine));
    lineList.remove(15);
    String[] newLine = lineList.toArray(new String[lineList.size()]);
    writer.writeNext(newLine, true);
}
writer.close();
reader.close();

一些其他说明：

如果要以生产能力使用，则代码可能需要更多的错误处理等。
列表java中的索引从0开始，因此删除[15]实际上从文件中删除了第16列。
该代码将其输出写入单独的文件。尝试使用相同的文件名进行输入和输出将不起作用。

I'm assuming you're using the OpenCSV library.

In order to make your code work, you have to fix 2 issues:

You need a writer to write your modified CSV to. OpenCSV provides a CSVWriter class for this purpose.
You need to convert your line (which is currently a String array) into a list to be able to remove an element, then convert it back into an array to match what the CSVWriter.writeNext method expects.

Here's some code that does this:

CSVReader reader = new CSVReader(new FileReader(fileName));
CSVWriter writer = new CSVWriter(new FileWriter(outFileName));
String[] origLine;
while ((origLine = reader.readNext()) != null) {
    List<String> lineList = new ArrayList<>(Arrays.asList(origLine));
    lineList.remove(15);
    String[] newLine = lineList.toArray(new String[lineList.size()]);
    writer.writeNext(newLine, true);
}
writer.close();
reader.close();

Some additional remarks:

The code probably needs a bit more error handling etc if it's to be used in a production capacity.
List indices in Java start at 0, so remove[15] actually removes the 16th column from the file.
The code writes its output to a separate file. Trying to use the same file name for input and output will not work.

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