is it possible to check if a char matches a list of possibilities?

Question

For example I know that when checking strings, you can do something like

if (string.matches(\"a|e|i|o|u|A|E|I|O|U\" ) )
{
   // Then do this code.
}
<         


        

Answer 1

Back before we had Unicode, when the character set was only 128 characters (ASCII) or later 256 (ISO 8859-1), we would often just create an array of Booleans and use a lookup on the character code--very fast. You could still do the same (an array of 65536 booleans isn't all that big by today's memory standards), or something like

static boolean[] vowelSet = new boolean[128]; // all initialized to false by default

static {
    vowelSet['A'] = true;
    vowelSet['E'] = true;
    ...
    vowelSet['u'] = true;
}

and then to look up:

boolean isVowel(char ch) {
    return ch < 128 && vowelSet[ch];
}

I think that's still the approach I'd take if efficiency were extremely important. Usually it isn't, so one of the other answers probably gives you more readable code.