Unique Characters in a String

class C1_1
{
  public static void main(String[] args)
  {
    System.out.println(isUnique("fayimora"));
    System.out.println(isUnique("fayi"));
    System.out.println(isUnique("aaaaaaaa"));
    System.out.println(isUnique(""));
    System.out.println(isUnique("  "));
    
    System.out.println("\n\nUNIQUED");
    System.out.println(isUniqueD("fayimora"));
    System.out.println(isUniqueD("fayi"));
    System.out.println(isUniqueD("aaaaaaaa"));
    System.out.println(isUniqueD(""));
    System.out.println(isUniqueD(" "));
    
  }
  
  public static boolean isUnique(String word)
  {
    int length = word.length();
    if(length==0) return true;
    for(int i=0; i<length; i++)
    {
      char a = word.charAt(i);
      for(int j=i+1; j<length; j++)
      {
        char b = word.charAt(j);
        if(a==b) return false;
      }
    }
    return true;
  }

  public static boolean isUniqueD(String word)
  {
    boolean[] ascii = new boolean[256];
    for(int i=0; i<word.length(); i++)
    {
      int val = word.charAt(i);
      if(ascii[val]) return false;
      ascii[val]=true;
    }
    return true;
  }
}