Java. Ignore accents when comparing strings

Question

The problem it's easy. Is there any function in JAVA to compare two Strings and return true ignoring the accented chars?

ie

String x = "Joao";
String y = "João";

return that are equal.

Thanks

Answer 1

The problem with these sort of conversions is that there isn't always a clear-cut mapping from accented to non-accented characters. It depends on codepages, localizations, etc. For example, is this a with an accent equivalent to an "a"? Not a problem for a human, but trickier for the computer.

AFAIK Java does not have a built in conversion that can look up the current localization options and make these sort of conversions. You may need some external library that handles unicode better, like ICU (http://site.icu-project.org/ )

Answer 2

You didn't hear this from me (because I disagree with the premise of the question), but, you can use java.text.Normalizer, and normalize with NFD: this splits off the accent from the letter it's attached to. You can then filter off the accent characters and compare.

Answer 3

In Spanish, n and ñ are considered different letters. Sorts between n and o. There's even a separate keyboard key.

As far as I know, in German, "ö" should be considered equal to "oe", not "o".

How are you going to handle all that? :)

Answer 4

I think you should be using the Collator class. It allows you to set a strength and locale and it will compare characters appropriately.

From the Java 1.6 API:

You can set a Collator's strength property to determine the level of difference considered significant in comparisons. Four strengths are provided: PRIMARY, SECONDARY, TERTIARY, and IDENTICAL. The exact assignment of strengths to language features is locale dependant. For example, in Czech, "e" and "f" are considered primary differences, while "e" and "ě" are secondary differences, "e" and "E" are tertiary differences and "e" and "e" are identical.

I think the important point here (which people are trying to make) is that "Joao"and "João" should never be considered as equal, but if you are doing sorting you don't want them to be compared based on their ASCII value because then you would have something like Joao, John, João, which is not good. Using the collator class definitely handles this correctly.