生成字母和数字组合的随机数

/**     * 生成指定长度的随机数字和字母     * @param length     * @return     */    public static String getStringRandom(int length) {          String val = "";          Random random = new Random();          for(int i = 0; i < length; i++) {              String charOrNum = random.nextInt(2) % 2 == 0 ? "char" : "num";              switch (charOrNum) {                case "char":                    int temp = random.nextInt(2) % 2 == 0 ? 65 : 97;                      val += (char)(random.nextInt(26) + temp);                    break;                case "num":                    val += String.valueOf(random.nextInt(10));                      break;            }        }          return val;      }