如何使用java生成1000个唯一的电子邮件ID [英] How to generate 1000 unique email-ids using java

问题描述

我的要求是用Java生成1000个唯一的电子邮件ID。我已经生成了随机文本并使用for循环我限制了要生成的电子邮件ID的数量。问题是，当我执行10个电子邮件时，会生成所有相同的电子邮件。

My requirement is to generate 1000 unique email-ids in Java. I have already generated random Text and using for loop I'm limiting the number of email-ids to be generated. Problem is when I execute 10 email-ids are generated but all are same.

以下是代码和输出：

public static void main() {
    first fr = new first();
    String n = fr.genText()+"@mail.com";

    for (int i = 0; i<=9; i++) {
        System.out.println(n);
    }
}

public String genText() {
    String randomText = "abcdefghijklmnopqrstuvwxyz";
    int length = 4;
    String temp = RandomStringUtils.random(length, randomText);
    return temp;
}

输出为：

[e-mail]
[e-mail]
...
[e-mail]

当我执行相同的上述程序时，我得到另一组mail-id。示例：而不是'myqo'它将是'bfta'。但我的要求是生成不同的唯一ID。

When I execute the same above program I get another set of mail-ids. Example: instead of 'myqo' it will be 'bfta'. But my requirement is to generate different unique ids.

例如：

[e-mail]
[e-mail]
[e-mail]

推荐答案

在中为语句添加字符串初始化：

for (int i = 0; i<=9; i++) {
    String n = fr.genText()+"@mail.com";
    System.out.println(n);
}

我想稍微改写一下你的方法：

I would like to rewrite your method a little bit:

public String generateEmail(String domain, int length) {
    return RandomStringUtils.random(length, "abcdefghijklmnopqrstuvwxyz") + "@" + domain;
}

可以这样打电话：

generateEmail("gmail.com", 4);

据我所知，你想生成独特的1000封电子邮件，然后你可以通过Stream API以方便的方式执行此操作：

As I understood, you want to generate unique 1000 emails, then you would be able to do this in a convenient way by Stream API:

Stream.generate(() -> generateEmail("gmail.com", 4))
      .limit(1000)
      .collect(Collectors.toSet())

但问题仍然存在。我故意将 Stream< String> 收集到 Set< String> （删除重复项）以查找其尺寸（）。正如您所看到的，大小并不总是等于 1000

But the problem still exists. I purposely collected a Stream<String> to a Set<String> (which removes duplicates) to find out its size(). As you may see, the size is not always equals 1000

999
1000
997

这意味着即使是这么小的算法，你的算法也会返回重复的值范围。

that means your algorithm returns duplicated values even for such small range.

因此，您最好研究已编写的Java电子邮件生成器或改进自己的（例如，通过添加数字，一些特殊字符，反过来，将生成大量例外情况）。

Therefore, you'd better research already written email generators for Java or improve your own (for example, by adding numbers, some special characters that, in turn, will generate a plenty of exceptions).

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