java摘要。md5Hex返回相同的值

Question

有人能说出为什么这段Java代码返回这么多相同的MD5值吗：

public static void main(String[] args) throws Exception{
    Random rnd = new Random();
    for (int i = 0; i < 1000; i++) {
      String key = DigestUtils.md5Hex(rnd.nextFloat() + System.currentTimeMillis() + "");
      System.out.println(key + ", " + rnd.nextFloat() + System.currentTimeMillis() + "");
    }
  }

这是我得到的输出：

814788aa9b6a22bf73ff3ae5fe0c6e0c, 0.15059251440334190624
814788aa9b6a22bf73ff3ae5fe0c6e0c, 0.599991561440334190624
814788aa9b6a22bf73ff3ae5fe0c6e0c, 0.54911111440334190624
814788aa9b6a22bf73ff3ae5fe0c6e0c, 0.0982222561440334190624
814788aa9b6a22bf73ff3ae5fe0c6e0c, 0.169987141440334190624
814788aa9b6a22bf73ff3ae5fe0c6e0c, 0.032851281440334190624
814788aa9b6a22bf73ff3ae5fe0c6e0c, 0.223390041440334190624
814788aa9b6a22bf73ff3ae5fe0c6e0c, 0.70173611440334190624
....
....
....

Answer 1

对不起，我的错：）

显然：

rnd.nextFloat() + System.currentTimeMillis()

只需将这两个数字相加，得到一个非常小的数字，在Java中表示为相同的字符串