Java sort strings in codepoint (UTF-32) order

Question

Other than to convert to UTF-8 bytes, or write a compare function that iterates and compares, is there some method I'm missing in JDK 1.6 that compares two strings in full Unicode codepoint order instead of in UCS-2 codepoint order?

I appreciate that this is not a hard thing to code. I was puzzled, however, that 1.6 has the various 'codepoint' APIs in java.lang.String as well as the Collation system, but apparently nothing to simply compare two strings without hiccuping on the surrogates.

For the benefit of a commenter, I have to feed some data to a tool that wants the strings in this order.

It already does that by default? Or do you actually want to take account with diacritics in the ordering? E.g. aa, aà, ab instead of (default) aa, ab, aà? Otherwise I don't see any reason for this question :) — BalusC
– BalusC, Commented Jan 22, 2010 at 21:00
String.compareTo is at least in Sun's JVM 1.6.0_16 implemented as a comparison of the contained chars. This will not work with bmargulies requirement if the string contains surrogate pairs for characters outside the BMP. — jarnbjo
– jarnbjo, Commented Jan 22, 2010 at 21:43
Actually, this behaviour is described in the API documentation, so it's not an implementation detail of Sun's VM to base compareTo on the char values. — jarnbjo
– jarnbjo, Commented Jan 22, 2010 at 21:55
Is there now a solution for this in the current Java 1.8/1.9 API? Or maybe within a library? — Rolch2015
– Rolch2015, Commented Jun 3, 2018 at 9:56

jarnbjo · Accepted Answer · 2010-01-22 21:53:12Z

1

AFAIk, the API has no such method, but it should be trivial to implement it yourself. Just out of curiosity: What do you need something like that for?

answered Jan 22, 2010 at 21:53

jarnbjo

34.4k7 gold badges75 silver badges95 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Rolch2015 · Accepted Answer · 2018-06-03 12:13:16Z

0

For the sake of completeness her my solution to the problem. Maybe there is a better solution:

   String sortedText = text
      .codePoints()
      .sorted()
      .mapToObj(i -> String.valueOf(Character.toChars(i)))
      .collect(Collectors.joining(""));

answered Jun 3, 2018 at 12:13

Rolch2015

1,5911 gold badge18 silver badges25 bronze badges

Collectives™ on Stack Overflow

Java sort strings in codepoint (UTF-32) order

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related