Processing a CSV File to Map<String,String[]> using Java 8

Question

I want to collect a CSV file into a map with the map key being the first string of the row (line[0]) and the map value as a string array of the rest of the row excluding line[0].

.collect(Collectors.toMap(line ->line[0], ));

unsure what to input as the second parameter of the .toMap method to achieve this

public Map<String,String[]> readFile() {

        try {
            Path path = Paths.get("src/CSV/map.csv");
            BufferedReader reader = new BufferedReader(Files.newBufferedReader(path, Charset.forName("UTF-8")));
            return reader.lines()
                    .map(line -> line.split(","))
                    .collect(Collectors.toMap(line ->line[0], ));
        } catch (IOException e) {
            throw new UncheckedIOException(e);
        }

v.ladynev · Accepted Answer · 2019-11-16 10:36:53Z

2

Or use this:

.collect(Collectors
   .toMap(line -> line[0], line-> Stream.of(line).skip(1).toArray(String[]::new)));

edited Nov 16, 2019 at 10:36

v.ladynev

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answered Nov 10, 2019 at 13:04

Hadi

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2 Comments

Ousmane D. Over a year ago

if you're going to use a stream then this would be better IMO --> Arrays.stream(line, 1, line.length).toArray(String[]::new)

Gooze_Berry Over a year ago

thanks for the suggestions, not encountered a stream inside a stream before

Hadi · Accepted Answer · 2019-11-10 12:59:32Z

1

use Arrays.copyOfRange:

.collect(Collectors.toMap(line -> line[0], line->Arrays.copyOfRange(line, 1, line.length)));

edited Nov 10, 2019 at 12:59

Hadi

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answered Nov 10, 2019 at 12:55

Ousmane D.

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