StringTokenizer? Convert the String to a char[] and iterate over that? Something else?
If you need to iterate through the code points of a String (see this answer) a shorter / more readable way is to use the CharSequence#codePoints method added in Java 8:
for(int c : string.codePoints().toArray()){
...
}
or using the stream directly instead of a for loop:
string.codePoints().forEach(c -> ...);
There is also CharSequence#chars if you want a stream of the characters (although it is an IntStream, since there is no CharStream).