Random random = new Random(); ArrayList list = new ArrayList(); for (int i = 0; i < 7; i++) { int num = random.nextInt(100); //100指生成 0-99之间的随机数 list.add(num); } for (Integer i : list) { if (i / 10 == 0) { //在这里判定是否是个位数,如果是,将 0 补在个位数前面,转换成字符串输出 System.out.print("0" + i + " "); } else { System.out.print(i + " "); } } }