隨機6位數

private static int randomOne(int length){ int[] array = {0,1,2,3,4,5,6,7,8,9}; Random rand = new Random(); for (int i = 10; i > 1; i--) { int index = rand.nextInt(i); int tmp = array[index]; array[index] = array[i - 1]; array[i - 1] = tmp; } int result = 0; for(int i = 0; i < length; i++) result = result * 10 + array[i]; return result; } private static String randomString(int length) { String format = "%0" + length + "d"; return String.format(format, randomOne(length)); } private static String randomTwo(){ Random rand = new Random(); return new StringBuilder().append(rand.nextInt(10)) .append(rand.nextInt(10)) .append(rand.nextInt(10)) .append(rand.nextInt(10)) .append(rand.nextInt(10)) .append(rand.nextInt(10)).toString(); }