BRAINLETS IF CORRECT!!! can someone help me make comments for this code please? not the first line tho

public int longestPrefix( String a, String b ) {
int count = 0;
int shortStringLength = 0;
if (a. length() > b. length()) shortStringLength = b. length();
else shortStringLength = a. length();
for (int i = 0; i < shortStringLength; i++) {
if (a. charAt(i) == b. charAt(i)) count ++;
else break;
}

return count;
}