How to convert UTF-8 to US-Ascii in Java

We have a system where customers, mainly European enter texts (in UTF-8) that has to be distributed to different systems, most of them accepting UTF-8, but now we must also distribute the texts to a US system which only accepts US-Ascii 7-bit

So now we'll need to translate all European characters to the nearest US-Ascii. Is there any Java libraries to help with this task?

Right now we've just started adding to a translation table, where Å (swedish AA)->A and so on and where we don't find any match for an entered character, we'll log it and replace with a question mark and try and fix that for the next release, but it seems very inefficient and somebody else must have done something similair before.

Solution 1:

You can do this with the following (from the NFD example in this Core Java Technology Tech Tip):

public static String decompose(String s) {
    return java.text.Normalizer.normalize(s, java.text.Normalizer.Form.NFD).replaceAll("\\p{InCombiningDiacriticalMarks}+","");
}

Solution 2:

The uni2ascii program is written in C, but you could probably convert it to Java with little effort. It contains a large table of approximations (implicitly, in the switch-case statements).

Be aware that there are no universally accepted approximations: Germans want you to replace Ä by AE, Finns and Swedes prefer just A. Your example of Å isn't obvious either: Swedes would probably just drop the ring and use A, but Danes and Norwegians might like the historically more correct AA better.