String Utils join in not working as expected

Question

I have a list of strings which is returned from a query in List A.

I am trying to use String Utils.join to combine the values in the list to a string separated by comma and in quotes. But it is not working as expected.

Values in abcList - [abc, cde, fgh]

abcList.addAll(jdbcTemplate.queryForList(abcSql, String.class));
String abc= StringUtils.join(abcList, "','");
abc = "'" +abc+ "'";

Expected output - 'abc', 'cde', 'fgh'
Actual output - 'abc, cde, fgh'

I am not sure what I am doing wrong here as I want to pass the values form the string abc into query with "IN" condition.

Works as expected on my computer.. Which version of StringUtils are you using? — Tobb, Mar 21 '18 at 15:18
Using this import import org.apache.commons.lang3.StringUtils with jar version 3.1 — user6591323, Mar 21 '18 at 15:36
Why don't you just use the query `abcSql` itself directly as a subquery in the `IN` clause instead of getting the actual strings? — DodgyCodeException, Mar 21 '18 at 15:40
I cannot use the abcSql directly in the in clause because the column that it will return contains comma separated strings instead of multiple rows. So thats why I was not able to use StringUtil.join as expected. Since it is a single string. Found my mistake. Thanks guys — user6591323, Mar 21 '18 at 16:56

score 1 · Answer 1 · answered Mar 21 '18 at 15:28

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As alternative you can also use stream.Collectors.joining

List<String> myList = Arrays.asList("abc","def","ghi");
String joined = myList.stream().collect(Collectors.joining("','", "'", "'"));
System.out.println(joined);

answered Mar 21 '18 at 15:28

Eritrean

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Tobi · Answer 2 · 2018-03-21T15:39:19.987

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If you are using Java 8 you can use the native method for joining strings.

List<String> list = <get a list of strings somehow>;
String joinedString = String.join("','", list);

See the String.join javadoc

Just as a hint for JDBC queries...you should use named parameters for inserting the values in your query instead of manually constructing the query string.

See this SO post for an example.

edited Mar 21 '18 at 15:39

answered Mar 21 '18 at 15:29

Tobi

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Too bad, than @Erithrean's answer won't work either. Nevertheless, you should use named parameters for the query anyways (see my edit). If you do this, you won't have to add the quotes manually. – Tobi Mar 21 '18 at 15:41
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But these values, which are then used in an IN clause, come from another query.The OP should use that query directly as a subquery, instead of executing it, getting the result and injecting that into another query. – DodgyCodeException Mar 21 '18 at 15:44
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@DodgyCodeException Yes, I absolutely agree that it should be done that way. But I think it's still worth clarifying the misconception of how set parameters in a query, as it is security relevant in other cases. – Tobi Mar 21 '18 at 15:47

String Utils join in not working as expected

2 Answers2