java - 从数组中随机选择元素，而不选择两次

Question

我有 2 个数组，它们以相同的方式进行洗牌。基本上，一旦被要求避免打印出重复项，我想删除数组元素:

我该如何解决这个问题，我需要使用数组列表吗？我完全迷失了。

/*
 * *** Random Test ***
 * Allows the user to generate a random test
 * from a bank of 10 questions.
 */

// import java libraries
import java.util.Scanner;
import java.util.Random;

public class randomTest {
public static void main(String args[]) {
    Scanner sc = new Scanner (System.in);


    // Question bank
    String[] qBank = new String[] {"What is the capital of England?", 
            "Which animal comes first in the English dictionary",
            "How many days are there in a leap year?"};

    // Answer bank
    String[] aBank = new String[] {"London", 
            "Aardvark", 
            "366"};

    // How many questions?
    System.out.println("How many questions would you like? (1-10)");
    int numQuestions = Integer.parseInt(sc.nextLine());
    int asked = 0;

    // Already Asked
    int[] alreadyAsked = new int[numQuestions];


    while (numQuestions != asked) {

        // Random question
        int idx = new Random().nextInt(qBank.length);
        String question = (qBank[idx]);
        System.out.println(question);


        System.out.println("Enter your awnswer: ");
        String myAnswer = sc.nextLine();
        asked ++;


        if (myAnswer.equals(aBank[idx])) {
            System.out.println("Correct answer!");
        } else {
            System.out.println("Wrong answer");
        }
    }
    }
}

Answer 1

使用ArrayList<String>将是您最好的解决方案，那么您可以这样做 list.remove()删除使用的条目。

Collections.shuffle() 将打乱一个列表。不过，您可能真正想做的只是每次循环时从列表中随机选择一个元素:

 List<String> questions = new ArrayList<>();
 questions.add("question 1");
 questions.add("question 2");
 etc
 List<String> answers = new ArrayList<>();
 answers.add("answer 1");
 etc

 Random random = new Random();

 while (questionsRemaining-- > 0) {
     int q = random.nextInt(questions.size());
     // ask question questions.get(q);
     // check against answer answers.get(q);

     // Removed used
     questions.remove(q);
     answers.remove(q);
 }

实际上，虽然您最好定义一个 Question 对象并在其中包含 Q 和 A，但您不必维护两个列表，并且将来您可以添加更多数据(例如不同问题的不同分数，多个答案等)。