Get CSV file header using apache commons

Question

I have been looking for the past 2 hours for a solution to my problem in vain. I'am trying to read a CSV File using Apache commons ,I am able to read the whole file but my problem is how to extract only the header of the CSV in an array?

score 9 · Answer 1 · edited Apr 29 '21 at 15:33

9

I looked everywhere and even the solution above didn't work. For anyone else with this issue, this does.

Iterable<CSVRecord> records;
Reader in = new FileReader(fileLocation);
records = CSVFormat.EXCEL.withHeader().withSkipHeaderRecord(false).parse(in);
Set<String> headers = records.iterator().next().toMap().keySet();

Note that your use of .next() has consumed one row of the CSV.

edited Apr 29 '21 at 15:33

DwB

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answered Mar 12 '19 at 20:45

crehop

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score 6 · Accepted Answer · answered Mar 28 '16 at 19:25

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By default, first record read by CSVParser will always be a header record, e.g. in the below example:

CSVFormat csvFileFormat = CSVFormat.DEFAULT.withHeader(FILE_HEADER_MAPPING);
FileReader fileReader = new FileReader("file");
CSVParser csvFileParser = new CSVParser(fileReader, csvFileFormat);
List csvRecords = csvFileParser.getRecords();

csvRecords.get(0) will return the header record.

answered Mar 28 '16 at 19:25

Darshan Mehta

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This is an impossible answer. It appears to have been cribbed from https://examples.javacodegeeks.com/core-java/apache/commons/csv-commons/writeread-csv-files-with-apache-commons-csv-example/. Note that `FILE_HEADER_MAPPING` contains the header.. which is what the original question was asking for. – daveloyall Apr 06 '21 at 22:38
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As @daveloyall was pointing out, the answer does not address the original question as the code provided assumes that the header fields are already available in FILE_HEADER_MAPPING. I downvoted so better answers can bubble to the top. – Alex Voss Sep 10 '22 at 12:13

score 6 · Answer 3 · answered Aug 07 '19 at 03:13

6

BufferedReader br = new BufferedReader(new FileReader(filename));

CSVParser parser = CSVParser.parse(br, CSVFormat.EXCEL.withFirstRecordAsHeader());

List<String> headers = parser.getHeaderNames();

This worked for me. The last line is what you need, extracts the headers found by the parser into a List of Strings.

answered Aug 07 '19 at 03:13

Justin Geeslin

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CSVFormat.EXCEL is not working for me at all. Can you take a look at this and help me. https://stackoverflow.com/questions/67964627/how-to-read-excel-xlsx-multipartfile-using-apache-csv-parser-current-approac @Justin – Deepanshu Rathi Jun 14 '21 at 07:09

score 6 · Answer 4 · answered Apr 12 '22 at 21:34

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Since Apache Commons CSV v1.9.0, the withSkipHeaderRecord() & the withFirstRecordAsHeader() methods are deprecated. A builder interface is provided. Use it thusly:

CSVFormat.DEFAULT.builder()
    .setHeader()
    .setSkipHeaderRecord(true)
    .build();

answered Apr 12 '22 at 21:34

Lavie Tobey

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This is a good answer, but not complete. It sent me looking for more. I think you should add something like`Reader in = new FileReader(fileName, StandardCharsets.UTF_8);` and `CSVFormat cSVFormat = CSVFormat.DEFAULT.builder().setHeader().setSkipHeaderRecord(false).build();` and `Iterable records = CSVParser.parse(in, cSVFormat);` – SedJ601 Apr 20 '23 at 15:43

score 1 · Answer 5 · answered May 17 '21 at 04:14

1

In Kotlin:

val reader = File(path).bufferedReader()
val records = CSVFormat.DEFAULT.withFirstRecordAsHeader()
    .withIgnoreHeaderCase()
    .withTrim()
    .parse(reader)

println(records.headerNames)

answered May 17 '21 at 04:14

Mitchell Tracy

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score 0 · Answer 6 · answered Feb 20 '22 at 05:14

The code below works for me:

import java.io.FileReader;
import org.apache.commons.csv.*;

public static String[] headersInCSVFile (String csvFilePath) throws IOException {
        //reading file
        CSVFormat csvFileFormat = CSVFormat.DEFAULT;
        FileReader fileReader = new FileReader(csvFilePath);
        CSVParser csvFileParser = new CSVParser(fileReader, csvFileFormat);
        List csvRecords = csvFileParser.getRecords();
        
        //Obtaining first record and splitting that into an array using delimiters and removing unnecessary text
        String[] headers = csvRecords.get(0).toString().split("[,'=\\]\\[]+");
        String[] result = new String[headers.length - 6];
        for (int i = 6; i < headers.length; i++) {
            //.replaceAll("\\s", "") removes spaces
            result[i - 6] = headers[i].replaceAll("\\s", "");
        } 
        return result;
}

Get CSV file header using apache commons

6 Answers6