Question

大家好我想知道如何在java中的数组中创建一个从一组字符串（大约96个字符串）中随机取出10个字符串的方法...

字符串是从文本文件中获取的我已经创建了一个方法来读取文件并将变量赋给行我也创建了一系列问题

这是我读取文件和创建问题数组的代码

q是问题

选择

b ....

cA是正确答案

public static Question[] readAllQuestions() throws FileNotFoundException {
    int numberOfQuestions = CountQuestions();
    Question [] allQuestions = new Question[numberOfQuestions];
    Scanner file = new Scanner (new File("TestBank.txt"));
    String q = "";
    String aa = "";
    String bb = "";
    String cc = "";
    String dd = "";
    String ccA = "";
    int x = 0 ; 
    int k = 0 ; 
    while (x< (allQuestions.length-1)) {
        while (file.hasNext() && k == 0) {
            String ques[] = file.nextLine().split(" ");
            for (int ww = 0 ; ww< ques.length ; ww++) {
                q += ques[ww];
                q+=" ";
            }
            if(ques[0].equals("")) {
                k++ ; 
            }
        }
        while (k == 1) {
            String a[] = file.nextLine().split(" ");
            for (int ww = 0; ww< a.length; ww++) {
                aa += a[ww];
                aa+= " ";
            }
            if(a[0].equals("")) {
                k++ ;
            }
        }
        //file.hasNext() &&
        while (k == 2) {
            String b[] = file.nextLine().split(" ");
            for (int ww = 0 ; ww< b.length ; ww++) {
                bb += b[ww];
                bb+= " ";
            }
            if(b[0].equals("")) {
                k++;
            }
        }
        while (k == 3) {
            String c[] = file.nextLine().split(" ");
            for (int ww = 0; ww<c.length; ww++) {
                cc += c[ww];
                cc+= " ";
            }
            if(c[0].equals("")) {
                k++;
            }
        }
        while (k == 4) {
            String d[] = file.nextLine().split(" ");
            for (int ww = 0; ww< d.length; ww++) {
                dd += d[ww];
                dd+= " ";
            }
            if(d[0].equals("")) {
                k++;
            }
        }
        while (k == 5) {
            String cA[] = file.nextLine().split(" ");
            for (int ww = 0; ww<cA.length; ww++) {
                ccA += cA[ww];
                ccA += " ";
            }
            if(cA[0].equals("")) {
                k++;
            }
        }
        while (k == 6) {
            Question question = new Question(q,aa,bb,cc,dd,ccA);
            allQuestions[x] = question;
            q="";
            aa="";
            bb="";
            cc="";
            dd="";
            ccA="";
            x++;
            k=0;
        }
    } 
    return allQuestions;
}

任何想法？感谢

Answer 1

在我看来，你想要一个字符串数组中的10个随机字符串而不选择重复字符串。实现此目的的一种简单方法是使用Collections::shuffle随机置换元素，然后选择随机列表的子集。这是一个例子：

public static void main(String[] args) throws Exception
{
    String[] exStringArray = IntStream.range(0, 96)
            .mapToObj(Integer::toString)
            .toArray(size -> new String[size]);

    System.out.println(getRandomElements(Arrays.asList(exStringArray), 10));
}

private static <T> Collection<T> getRandomElements(Collection<T> c, int maxElements)
{
    List<T> deepCopiedList = new ArrayList<>(c);
    Collections.shuffle(deepCopiedList);
    return Collections.unmodifiableList(deepCopiedList.subList(0, Math.max(Math.min(deepCopiedList.size(), maxElements), 0)));
}

Answer 2

您可以使用随机类。 array[random.nextInt(array.length)]为0到array.length - 1之间的任何数字提供索引的数组元素，因为nextInt方法中排除了最后一个索引。

public static String[] getRandomStrings(String [] mainStrings, int i) {
    String [] randomStrings = new String[i];
    Random random = new Random();
    for(int index = 0; index < i ; index++){
        randomStrings[index] = mainStrings[random.nextInt(mainStrings.length)];
    }
    return randomStrings;
}

如何为字符串数组获取10个随机字符串？

2 个答案: