字母数字随机数序列[5位或6位或任何数字]生成

Question

您好，我正在尝试生成一个 5 位随机数，它本质上是字母数字。我在不使用 Streams 的情况下同时使用这两种方法。

代码

public class AlphaRandom {
    
    private static final String ALPHA_NUMERIC_STRING = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
    static final Random random = new Random();
    
    
    public static void main(String args[]) {
        int length = 5;
        String seq = randomAlphaNumeric(length);        
        System.out.println("Random Number Normal  : " +seq);        
        IntStream.range(0,1).forEach(i->System.out.println("Random Number Streams : " +generateRandomString(random, length)));
        
    }
    
    // Using Streams
    private static String generateRandomString(Random random, int length){
        return random.ints(48,122)
                .filter(i-> (i<57 || i>65) && (i <90 || i>97))
                .mapToObj(i -> (char) i)
                .limit(length)
                .collect(StringBuilder::new, StringBuilder::append, StringBuilder::append)
                .toString();
    }
    
    // Normal 
    public static String randomAlphaNumeric(int count) {

        StringBuilder builder = new StringBuilder();    
        while (count-- != 0) {  
            int character = (int)(Math.random()*ALPHA_NUMERIC_STRING.length()); 
            builder.append(ALPHA_NUMERIC_STRING.charAt(character)); 
        }   
        return builder.toString();
    }
}

样本输出：

Random Number Normal  : VYAXC
Random Number Streams : LdBN6

Random Number Normal  : 2ANTT
Random Number Streams : hfegc

Random Number Normal  : JWK4Y
Random Number Streams : 8mQXK

但我无法生成仅以UpperCase 开头的序列。 谁能帮帮我。

Answer 1

我将使用 apache 库中的 RandomStringUtils 来执行此操作。这样做的原因是代码更少，我相信代码的可读性更好。

这是我的代码，可以做需要的事情

import org.apache.commons.lang3.RandomStringUtils;

public class GenerateRandomString {
    public static void main(String[] args) {
        int keyLength = 5; // Number of character allowed as per requirement
        String randomAlphanumeric = RandomStringUtils.randomAlphanumeric(keyLength);
        System.out.println("randomAlphanumeric generated is " + randomAlphanumeric);
        String upperCaseRandom = randomAlphanumeric.substring(0, 1).toUpperCase() + randomAlphanumeric.substring(1);
        System.out.println("upperCaseRandom generated is " + upperCaseRandom);
    }
}

它将生成以下输出：

randomAlphanumeric generated is m8OiR
upperCaseRandom generated is M8OiR

我正在使用 substring 方法根据问题的要求将第一个字符转为大写。

Answer 2

最简单的方法是在返回你的字符串之前（一旦你生成它），你取第一个字母以应用toUpperCase，然后在剩余的字符上应用toLowerCase。此外，如果将来您需要生成更长的字符串，您可以使用相同的方法而无需更改任何内容。

夏天我们要做的是：

public static String manipulate (String rand){
    String c = rand.substring(0,1); // where rand is the random alphanumeric generated by your methods, we pick the first char
    c = c.toUpperCase(); //we make it upperCase
    String split = rand.substring(1); //we get the remaining of the string starting from position 1
    split = split.toLowerCase(); //let's apply lowercase on the remaining
    String result = c+split; //join again
    return result;
}

完整代码：

package test;

import java.util.Random;
import java.util.stream.IntStream;

public class AlphaRandom {

    private static final String ALPHA_NUMERIC_STRING = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
    static final Random random = new Random();


    public static void main(String args[]) {
        int length = 5;
        String seq = randomAlphaNumeric(length);
        System.out.println("Random Number Normal  : " +seq);
        IntStream.range(0,1).forEach(i->System.out.println("Random Number Streams : " +generateRandomString(random, length)));

    }

    public static String manipulate (String rand){
        String c = rand.substring(0,1); // where rand is the random alphanumeric generated by your methods, we pick the first char
        c = c.toUpperCase(); //we make it upperCase
        String split = rand.substring(1); //we get the remaining of the string starting from position 1
        split = split.toLowerCase(); //let's apply lowercase on the remaining
        String result = c+split; //join the again
        return result;
    }

    // Using Streams
    private static String generateRandomString(Random random, int length){
        String rand =  random.ints(48,122)
                .filter(i-> (i<57 || i>65) && (i <90 || i>97))
                .mapToObj(i -> (char) i)
                .limit(length)
                .collect(StringBuilder::new, StringBuilder::append, StringBuilder::append)
                .toString();
        return manipulate(rand);
    }

    // Normal
    public static String randomAlphaNumeric(int count) {

        StringBuilder builder = new StringBuilder();
        while (count-- != 0) {
            int character = (int)(Math.random()*ALPHA_NUMERIC_STRING.length());
            builder.append(ALPHA_NUMERIC_STRING.charAt(character));
        }
        return manipulate(builder.toString());
    }
}

输出：

Random Number Normal  : Mwwsz
Random Number Streams : Q1fqk