Comparing strings and get the first place where they vary from eachother

Question

I want to get the first place where 2 string vary from each other. example: for these two strings: \"AAAB\" \"AAAAC\"

I want to get the result 4.

How do i d

Answer 1

int compare( String a, String b ){

   for( int i = 0; i < min( a.length, b.length ); i++ ){

      if( a.getCharAt(i) != b.getCharAt(i) ){
         return i;
      }

  }

  return -1; //a contained in b, or b contained in a

} 

The code above doesn't check anything like nulls, etc.