java - 使用子字符串进行随机化

Question

我这里的代码只能随机化长度，我需要随机化我的类 createPassword 中的字符串。但是不存在随机化字符串的方法，只能随机化整数。有人有什么建议吗？

主要:

public class Program {
    public static void main(String[] args) {
        PasswordRandomizer randomizer = new PasswordRandomizer(13);
        System.out.println("Password: " + randomizer.createPassword());
        System.out.println("Password: " + randomizer.createPassword());
        System.out.println("Password: " + randomizer.createPassword());
        System.out.println("Password: " + randomizer.createPassword());
}
}

类(class):

import java.util.Random;

public class PasswordRandomizer {
    private Random random = new Random();
    private int length;

    public PasswordRandomizer(int length) {
        this.length=length;
        random = new Random();
    }

    public String createPassword() {
        String alphabet = "abcdefghijklmnopqrstuvwxyz";
        int randomCharIndex = random.nextInt(length);
        String randomstr = alphabet.substring(randomCharIndex); 
        return randomstr;
    }
}

输出示例:

Password: ghijklmnopqrstuvwxyz
Password: lmnopqrstuvwxyz
Password: jklmnopqrstuvwxyz
Password: ijklmnopqrstuvwxyz

Answer 1

这会很好地工作:

    public String createPassword() {
        StringBuilder pass = new StringBuilder();
        Random r = new Random();

        for(int i = 0 ; i < length ; i++) {
            pass.append( (char)('a' + r.nextInt('z'-'a')) );
        }
        return pass.toString();
    }

这个想法是利用char可以用作int并转换回char(并且字母字符是连续的)以 ASCII 码表示)。所以你用它来获得一个随机字符:
minimumValue + random.nextInt(MaxValue-MinValue)