我如何 return 到 while 循环的开头？

Question

我只学习编码类一个月，所以如果我使用了一些 wrong/wacky 结构，我真的很抱歉。

我正在尝试使用两个随机数制作一个加法游戏； r1 确定加法问题中的项数，而 r2 为每个项分配一个值。扫描器会检查用户的输入，并根据该信息给游戏打分或计算失败的尝试次数。

问题是第一次迭代运行良好，但它从未显示出新问题，即使没有满足主 while 循环的条件（3 个错误答案）。

能否请您指点一下？谢谢！

import java.util.Random;
import java.util.Scanner;
import java.util.ArrayList;
public class AddingGame {
    Random rand1, rand2;
    int points = 0, wrong = 0, sum;
    String str = "";
    Scanner sc;
    ArrayList <Integer> mem;
    public AddingGame() {
        sc = new Scanner(System.in);
        rand1 = new Random();
        rand2 = new Random();
        int r1, r2, i;
        mem = new ArrayList <> ();
        System.out.println("Input any integer to receive a problem. Answer the problem correctly to proceed. Each correct answer yields a point. After three incorrect attempts, the game ends.");
        while (wrong <= 3) {
            mem.removeAll(mem);
            sum = 0;
            i = 0;
            str = "";
            
            r1 = rand1.nextInt(5) + 2; // determines the number of terms of a problem
            while (mem.size() <= (r1 - 1)) {
                r2 = rand2.nextInt(50) + 1; // determines the value of each term
                mem.add(r2);
                sum += r2;
                if (i == (r1 - 1)) {
                str = str + mem.get(i) + " = ?";
                } else {  
                str = str + mem.get(i) + " + "; 
                }  
                i++;
            }
            System.out.println(str);
            correct();
            while (sc.nextInt() != sum) {
                System.out.println("Try again!");
                System.out.println(str);
                wrong++;
                if (wrong == 3) {
                   System.out.println("You're out of attempts!");
                   break;
                }
                correct();
             }
        }
    }
    
    private void correct() {
        if (sc.nextInt() == sum) {
            points++;
            if (points != 1) {
                System.out.println("Correct! You now have " + points + " points!" );
            } else {
                System.out.println("Correct! You now have " + points + " point!" );
            }                
        }
    }
}

Answer 1

我想你可能希望看到这个游戏的更简单的实现，因为我注意到你正在努力弄清楚你需要什么变量，什么数据结构会有帮助等等！

希望这可以帮助您更好地理解如何在 Java:

中构建程序

import java.util.Random;
import java.util.Scanner;

public class AddingGame {
    Random rand = new Random(); // no reason to have more than one instance of Random
    int points; // ints are automatically initialized to zero
    Scanner sc = new Scanner(System.in);

    public AddingGame() {
        System.out.println("Input any integer to receive a problem. Answer the problem correctly to proceed. Each correct answer yields a point. After three incorrect attempts, the game ends.");
        mainLoop:
        do { // keep playing until player gives up
            int sum = 0;
            String question = "";
            int termsCount = rand.nextInt(5) + 2; // determines the number of terms of a problem

            for (int i = 0; i < termsCount; i++) {
                int term = rand.nextInt(50) + 1; // determines the value of each term
                sum += term;
                if (i == termsCount - 1) { // this is the last term
                    question += term + " = ? ";
                } else {
                    question += term + " + ";
                }
            }
            System.out.print(question);
            int wrong = 0;
            while (!checkAnswerIsCorrect(sum)) {
                wrong++;
                if (wrong == 3) {
                    System.out.println("You're out of attempts!");
                    break mainLoop; // get out of mainLoop, not just the current one!
                }
                System.out.println("Try again!");
                System.out.print(question);
            }
        } while (shouldContinuePlaying());

        System.out.println("Total Points: " + points);
        System.out.println("GAME OVER!");
    }

    private boolean checkAnswerIsCorrect(int sum) {
        if (sc.nextInt() == sum) {
            points++;
            System.out.println("Correct! You now have " + points + " point" +
                    (points == 1 ? "" : "s") + "!");
            return true;
        }
        return false;
    }

    private boolean shouldContinuePlaying() {
        System.out.print("Continue playing? ");
        return sc.next().equals("yes");
    }

    public static void main(String[] args) {
        new AddingGame();
    }
}

我建议您在了解我的更改后将循环拆分为单独的方法...这将使您更容易“专注于”游戏的单个部分，而不必将所有内容都保留在您的当你阅读代码时，请注意...我将大部分字段移至局部变量，因为在任何给定时间范围内只包含少量内容（你可以“看到”的变量）总是更可取 - 再次，以帮助程序员理解什么值很重要并 can/should 被使用。

祝你好运，希望你有一个伟大的程序员职业。

我如何 return 到 while 循环的开头？

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