Is there a way to compare 2 Strings without it being case-sensitive?

Question

I've just spent almost hour debugging a List<String> in my code which was being sorted wrong by my Comparator.

Turns out that string.compareTo(string2) is case-sensitive. Meaning that all Capital letters come before the lowercase letters. e.g. "Z" comes before "d".

Is there any better way of comparing 2 Strings inside a Comparatorand sorting them alphabetically ascending without them being case sensitive other then string.toLowerCase().compareTo(string2.toLowerCase()); ?

Edit: There's a possibility of any accented letter appearing in my String like for example: ä, ö, ü, é, è, etc.

@SofoGial That checks equality only, not which is bigger or smaller which `copareTo` does and which is required to establish sorting order. — Pshemo, Nov 16 '18 at 09:41
@DodgyCodeException yes I do, sry for forgetting to Mention that. There's the possibility of accented letters existing like for example: ä, ö, ü, è, é, etc... — D.Mendes, Nov 16 '18 at 09:51
@D.Mendes While accented characters are handled by ignoring the case, it will assume a != ä but ä == Ä — Peter Lawrey, Nov 16 '18 at 09:53
Related (perhaps even duplicate): https://stackoverflow.com/questions/2220400/how-do-i-make-my-string-comparison-case-insensitive and for further information https://stackoverflow.com/questions/8885885/difference-between-collator-locale-sensitive-and-compareto-lexicographically — Hulk, Nov 16 '18 at 10:13

Mark Rotteveel · Accepted Answer · 2018-11-16T09:59:17.863

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You have two options provided in String itself:

String.compareToIgnoreCase(String): case insensitive variant of compareTo)
String.CASE_INSENSITIVE_ORDER: Comparator that has the same ordering as compareToIgnoreCase
or, for more advanced options like locale-specific rules, java.text.Collator and java.text.RuleBasedCollator

As a tip: your first stop should be the Javadoc, not post a question on Stack Overflow: the Javadoc is extensive and will usually provide a quick answer.

edited Nov 16 '18 at 09:59

answered Nov 16 '18 at 09:42

Mark Rotteveel

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Or java.text.Collator. – DodgyCodeException Nov 16 '18 at 09:45
Yes, what @DodgyCodeException said, in case locale dependant order is required. – Pshemo Nov 16 '18 at 09:47
@DodgyCodeException Thanks, added a link to that one as well. – Mark Rotteveel Nov 16 '18 at 09:48

score 6 · Answer 2 · answered Nov 16 '18 at 09:40

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Use String.CASE_INSENSITIVE_ORDER.compare

answered Nov 16 '18 at 09:40

talex

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What about accented letters? – DodgyCodeException Nov 16 '18 at 09:42
@DodgyCodeException what about them? – luk2302 Nov 16 '18 at 09:42
@luk2302 CASE_INSENSITIVE_ORDER doesn't take locales into account. So it might deem f to come before é. The OP didn't specify whether é might possibly be present but it's not up to us to assume it won't be. – DodgyCodeException Nov 16 '18 at 09:44

score 1 · Answer 3 · answered Nov 16 '18 at 09:42

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use compareToIgnoreCase() method

https://docs.oracle.com/javase/9/docs/api/java/lang/String.html#compareToIgnoreCase-java.lang.String-

answered Nov 16 '18 at 09:42

e.g78

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https://docs.oracle.com/javase/9/docs/api/java/lang/String.html#compareToIgnoreCase-java.lang.String- – e.g78 Nov 16 '18 at 09:44

score 0 · Answer 4 · edited Jun 20 '20 at 09:12

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compareToIgnoreCase

The String Api has a second compare to function that does a compare while ignoring case.

string1.compareToIgnoreCase(string2);

edited Jun 20 '20 at 09:12

Community

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answered Nov 16 '18 at 09:42

Dinomaster

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Is there a way to compare 2 Strings without it being case-sensitive?

4 Answers4

compareToIgnoreCase