Convert List to delimited String

Question

Possible Duplicate:
Java: convert List<String> to a join()d string

Having this:

List<String> elementNames = Arrays.asList("h1", "h2", "h3", "h4", "h5", "h6");

What is an elegant way to get String with a custom delimiter, like so:

"h1,h2,h3,h4,h5,h6"

Sorry for the duplicate. Made a quick search and seemed to miss it. — Alp, Jun 05 '11 at 18:24

gouki · Answer 1 · 2016-10-18T23:45:30.637

38

StringBuilder sb = new StringBuilder();

for(String s: elementnames) {
   sb.append(s).append(',');
}

sb.deleteCharAt(sb.length()-1); //delete last comma

String newString = sb.toString();

Update: Starting java 8, you can obtain the same results using:

    List<String> elementNames = Arrays.asList("1", "2", "3");

    StringJoiner joiner = new StringJoiner(",", "", "");
    elementNames.forEach(joiner::add);

    System.out.println(joiner.toString());

edited Oct 18 '16 at 23:45

answered Jun 05 '11 at 18:15

gouki

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This is only if he minds using external libraries. =) – gouki Jun 05 '11 at 18:20
1

Upvote for no external libraries - I am refactoring ancient code with "vintage" dependencies that are fixed. – cschooley Jan 13 '14 at 20:07
3

The Java 8 version can be done on 1 line with Collectors. String joined = elementNames.stream().collect(Collectors.joining(",")); – wheeleruniverse Jun 21 '18 at 11:55

score 28 · Accepted Answer · edited Jul 07 '15 at 12:17

28

If you don't mind using the StringUtils library provided by apache, you could do:

// Output is "a,b,c"
StringUtils.join(["a", "b", "c"], ',');

https://commons.apache.org/proper/commons-lang/javadocs/api-2.6/org/apache/commons/lang/StringUtils.html

edited Jul 07 '15 at 12:17

Vishal Khandelwal

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answered Jun 05 '11 at 18:15

debracey

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+1 for compactness, i'll do it that way – Alp Jun 05 '11 at 18:20
3

StringUtils.collectionToDelimitedString – Jason Nethercott Jun 21 '12 at 13:20
1

And you can even pass in List and Iterable, not just arrays. – Elliot Vargas Jun 26 '13 at 20:43

Convert List to delimited String

2 Answers2