Java：随机生成不同的名称 [英] Java: Randomly generate distinct names

问题描述

我需要在Java中生成10,000个唯一标识符。标识符应该是数字和字母的混合，每个少于10个字符。有任何想法吗？内置库将是一个额外的加号。

I need to generate 10,000 unique identifiers in Java. The identifiers should be a mixture of numbers and letters and less than 10 characters each. Any ideas? Built in libraries would be an extra plus.

推荐答案

// class variable
final String lexicon = "ABCDEFGHIJKLMNOPQRSTUVWXYZ12345674890";

final java.util.Random rand = new java.util.Random();

// consider using a Map<String,Boolean> to say whether the identifier is being used or not 
final Set<String> identifiers = new HashSet<String>();

public String randomIdentifier() {
    StringBuilder builder = new StringBuilder();
    while(builder.toString().length() == 0) {
        int length = rand.nextInt(5)+5;
        for(int i = 0; i < length; i++) {
            builder.append(lexicon.charAt(rand.nextInt(lexicon.length())));
        }
        if(identifiers.contains(builder.toString())) {
            builder = new StringBuilder();
        }
    }
    return builder.toString();
}

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