In java, how to append string ignoring duplicates

Question

I have string say "ABC,D" , now I wish to write a method append(initialStr, currStr ) which appends currStr to initailStr only if currstr is not already present in initialStr. I tried a method which splits with comma, but since my string contains comma so that method doesn't works for me. Any help will be greatly appreciated.

Answer 1

String appendIfNotPresent(String initial, String curr)
{
   if (initial.contains(curr))
     return initial;
   else
     return initial + curr;
}