Question

What is the fastest / clearest way to see if a string matches to another string of the same length with X allowed mismatches? Is there a library that can do this, its not in Apache stringUtils (there is only one that also uses insertions / deletions).

So lets say I have 2 string of length for and I want to know if they match with 1 mismatch allowed. Insertions and deletions are not allowed.

So:

ABCD <-> ABCD = Match

ABCC <-> ABCD = Match with 1 mismatch

ACCC <-> ABCD = no match, 2 mismatches is too much.

Answer 1

String str1, str2;

Assuming the lengths of the strings are equal:

int i = 0;

for(char c : str1.toCharArray())
{
   if(c != str2.charAt(i++))
      counter++;
}

if(counter > 1)
  // mismatch