java随机生成n数字和字母的组合

下面是一个示例 Java 代码，用于生成指定长度的由数字和字母组成的随机字符串：

import java.security.SecureRandom;

public class RandomStringGenerator {
    
    private static final String CHARACTERS = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
    private static final SecureRandom SECURE_RANDOM = new SecureRandom();

    public static String generateRandomString(int length) {
        StringBuilder builder = new StringBuilder(length);
        for (int i = 0; i < length; i++) {
            int randomIndex = SECURE_RANDOM.nextInt(CHARACTERS.length());
            char randomChar = CHARACTERS.charAt(randomIndex);
            builder.append(randomChar);
        }
        return builder.toString();
    }
}

使用示例：

String randomString = RandomStringGenerator.generateRandomString(10); // 生成10个字符的随机字符串
System.out.println(randomString);

输出示例：

HNd3YkF7Gq