// Calling length() is the null pointer check (so do it before we can exit early).
    int length = s1.length();
    if (s1 == s2) {
      return true;
    }
    if (length != s2.length()) {
      return false;
    }
    for (int i = 0; i < length; i++) {
      char c1 = s1.charAt(i);
      char c2 = s2.charAt(i);
      if (c1 == c2) {
        continue;

    // Calling length() is the null pointer check (so do it before we can exit early).
    int length = s1.length();
    if (s1 == s2) {
      return true;
    }
    if (length != s2.length()) {
      return false;
    }
    for (int i = 0; i < length; i++) {
      char c1 = s1.charAt(i);
      char c2 = s2.charAt(i);
      if (c1 == c2) {
        continue;