How can I convert csv to List with Java 8?

Question

I want to get either empty list or list of strings from CSV. And I tried below approach:

String valueStr = "US,UK";
List<String> countryCodes = StringUtils.isBlank(valueStr)
                                    ? Collections.emptyList()
                                    : Arrays.stream(valueStr.split(DELIMITER))
                                            .map(String::trim)
                                            .collect(Collectors.toList());

How can I make it more concise without ternary operator, keeping it easy as well? This works fine. Just checking other approaches.

Try something like this : Optional.ofNullable(valueStr) .map(s->Arrays.stream(s.split(DELIMITER)) .map(String::trim) .collect(Collectors.toList())).orElse(Collections.emptyList()); — Hadi
– Hadi, Commented Aug 1, 2019 at 12:31

Eugene · Accepted Answer · 2019-08-01 12:39:48Z

1

static Pattern p = Pattern.compile(DELIMITER);

public static List<String> getIt(String valueStr) {

    return Optional.ofNullable(valueStr)
                   .map(p::splitAsStream)
                   .map(x -> x.map(String::trim).collect(Collectors.toList()))
                   .orElse(Collections.emptyList());
}

answered Aug 1, 2019 at 12:39

Eugene

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Comments

ernest_k · Accepted Answer · 2019-08-01 12:46:36Z

1

You can filter:

List<String> countryCodes = Arrays.stream(
            StringUtils.trimToEmpty(valueStr).split(DELIMITER))
        .filter(v -> !v.trim().isEmpty())
        .collect(Collectors.toList());

The above returns an empty list when tested with a blank. It also excludes blank values (such as the last value from "UK,")

edited Aug 1, 2019 at 12:46

answered Aug 1, 2019 at 12:38

ernest_k

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