Java loop through files to convert csv to xls

Question

Does anyone know how to loop through files in a directory with the script below? I have tried it but I don't know how to assign a variable to the following line:

CSVReader reader = new CSVReader(new FileReader(file));

It has to be a string which pops syntax errors.

import java.io.*;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.*;
import au.com.bytecode.opencsv.CSVReader;

class Test {
    public static void main(String[] args) throws IOException {
        Workbook wb = new HSSFWorkbook();
        CreationHelper helper = wb.getCreationHelper();
        Sheet sheet = wb.createSheet("new sheet");

        CSVReader reader = new CSVReader(new FileReader("data.csv"));
        String[] line;
        int r = 0;
        while ((line = reader.readNext()) != null) {
            Row row = sheet.createRow((short) r++);

            for (int i = 0; i < line.length; i++)
                row.createCell(i)
                   .setCellValue(helper.createRichTextString(line[i]));
        }

        // Write the output to a file
        FileOutputStream fileOut = new FileOutputStream("workbook.xls");
        wb.write(fileOut);
        fileOut.close();
    }
}

Answer 1

Hi i don't know if i correctly understand your question. But i would recommend trying something like this: You can use the Path and Files classes to loop through a directory. Then you can use your code for editing the files

import java.io.*;
import java.nio.file.DirectoryStream;
import java.nio.file.Files;
import java.nio.file.Path;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.*;
import au.com.bytecode.opencsv.CSVReader;

class Test {

    public static void main(String[] args) throws IOException {
// here you enter the path to your directory.
// for example: Path workDir = Paths.get("c:\\workspace\\csv-files")

        Path workDir = Paths.get("path/to/dir");
// the if checks whether the directory truly exists
        if (!Files.notExists(workDir )) {
// this part stores all files withn the directory in a list
            try (DirectoryStream<Path> directoryStream = Files.newDirectoryStream(workDir )) {
                for (Path path : directoryStream) {
                    Workbook wb = new HSSFWorkbook();
                    CreationHelper helper = wb.getCreationHelper();
                    Sheet sheet = wb.createSheet("new sheet");
// here you insert the name of the file (stored in the Path object) into your method
                    CSVReader reader = new CSVReader(new FileReader(path.toString()));
                    String[] line;
                    int r = 0;
                    while ((line = reader.readNext()) != null) {
                        Row row = sheet.createRow((short) r++);

                        for (int i = 0; i < line.length; i++)
                            row.createCell(i)
                                    .setCellValue(helper.createRichTextString(line[i]));
                    }

                    // Write the output to a file
                    FileOutputStream fileOut = new FileOutputStream(path.getName().replaceAll("csv", "xls"));
                    wb.write(fileOut);
                    fileOut.close();
                }

            } catch (IOException e) {
                System.out.println(e.getMessage());
            } else {
                 System.out.println("directory " + workDir.toString() + " does not exist" )

        }

    }
}