code: public static boolean startsWith(String str, char prefix) {
          return (str != null && !str.isEmpty() && (str.charAt(0) == prefix));
      }
docs: Test if the given {@code String} starts with the specified prefix character.
  
  @param str the {@code String} to check
  @param prefix the prefix character to look for
  @return true if the string starts with the specified prefix; otherwise false
  @see java.lang.String#startsWith