Question

我有两个以相同方式洗牌的数组。基本上我想删除数组元素一旦被要求避免重复打印出来：

如何解决此问题，是否需要使用数组列表？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>将是您的最佳解决方案，然后您可以list.remove()删除使用时的条目。

Collections.shuffle（）将随机播放一个列表。你可能真正想要做的只是在循环中每次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);
 }

实际上你最好定义一个Question对象并且在其中包含Q和A，那么你不必维护两个列表，并且将来你可以添加更多数据（比如不同问题的不同分数，多个答案，等等。）

Answer 2

如果您不想复制，请使用Set。要从List中删除重复项，可以使用Set s = new HashSet（list）;

Answer 3

使用2D数组并一起设置问题和答案。

String[][] example = new String[2][10];
example[0, 0] = "What is the capital of England?";
example[1, 0] = "London";

您不必以繁琐的方式输入它，它适用于您上面的数组实例化（使用{}）。

或者，ArrayList<String[]>。只需将String[]设置为{"question", "answer"}，然后将其添加到ArrayList。

从数组中随机选择元素而不选择两次元素

3 个答案: