Convert foreign characthers (Greek) to English ones.

I am installing alarms, but they have an interface that I have to give name to various zones. The problem is that they can only accept greek characters that does not exist in english language else they have to be the English equivelant. For example if I write "ΠΑΡΑΘΥΡΟ", the characthers 1,2,3,5,6,7 must enter in english because are the same with the greek ones in appearence. But chars 0 and 4 only must be in Greek. I care only for capitals. Any idea on how to do it with 2 simple jtextfields ? Thank you!

Solution

Use a HashMap to translate characters. Since the problem domain is small and will probably never change, it's justifiable to hard-code the content of the map, like so:

private static final Map<Character, Character> GREEK_TO_ROMAN = new HashMap<>();
static {
    GREEK_TO_ROMAN.put('\u0391', '\u0041');  // uppercase alpha
    GREEK_TO_ROMAN.put('\u03A1', '\u0050');  // uppercase rho
    // ...
}

Then get the input string's character array, translate characters as needed, and create a new String from the changed array:

String s = "ΠΑΡΑΘΥΡΟ";
char[] chars = s.toCharArray();
for (int i = 0; i < chars.length; i++) {
    Character repl = GREEK_TO_ROMAN.get(chars[i]);
    if (repl != null)
        chars[i] = repl;
    }
s = new String(chars);

How JTextField would come into play I don't quite see, but maybe if you want you can subclass it, overwrite the getText() method and make sure that any String it yields is already converted.