"Write a method that determines whether all the characters in a string are the same, using only library string methods, but no loops or recursion." Tests ... assertEquals(true, allDuplicateChars("cccccc")); assertEquals(false, allDuplicateChars("abcdef"));

DupeChecker.java

public class DupeChecker {
  public boolean allDuplicateChars(final String input) {
    if (input == null || input.length() == 0) {
        return false;
    }
    String firstChar = input.substring(0,1);
    String matchingChars[] = input.split(firstChar + "+");
    return matchingChars.length == 0;
  }
}