public static void permutation(String str)
{
  permutation(str, "");
}

public static permutation(String str, String prefix)
{
  if(str.length() == 0)
    System.out.println(prefix);
  else {
    String rem = str.substring(0, i) + str.substring(i + 1);
    permutation(rem, prefix + str.charAt(i));
  }
}