コマンドラインのQuizゲーム (Java 7 and later)

Quiz.java

package quiz;

import java.io.IOException;
import java.io.PrintStream;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;
import java.util.Scanner;

public final class Quiz {

    static PrintStream out = System.out;

    public static void main(String[] args) {
        // 準備
        List<Question> questions = readQuestions(args);
        final int qCount = questions.size();
        // 質問をランダムに
        Collections.shuffle(questions);
        // 質問番号
        int qNumber = 0;
        // 正答数
        int passedCount = 0;
        // 開始
        out.println("*** クイズゲーム ***");
        out.printf("全%d題%n", qCount);
        out.println();
        for (Question q : questions) {
            ++qNumber;
            if (question(qNumber, q)) {
                ++passedCount;
            }
        }
        // 終了
        out.println("終了。");
        out.printf("正答率 %.1f %% (%d/%d)%n", passedCount * 100f / qCount, passedCount, qCount);
    }

    static boolean question(int qNumber, Question q) {
        List<String> wrongAnswers = q.getWrongAnswers();
        // 選択肢数の計算
        final int choiceCount = wrongAnswers.size() + 1;
        String choiceChars = "ABCDEFGHIJ".substring(0, choiceCount);
        List<String> numbers = Arrays.asList(choiceChars.split(""));
        Collections.shuffle(numbers);
        String correctNumber = numbers.get(0); // 正解の番号
        // 表示用の選択肢
        List<String> choices = new ArrayList<>();
        // 先に正解を追加
        choices.add(String.format("%s. %s", correctNumber, q.getCorrectAnswer()));
        // 不正解を追加
        int i = 0;
        for (String wrong : wrongAnswers) {
            ++i;
            choices.add(String.format("%s. %s", numbers.get(i), wrong));
        }
        // 番号順に並べ直す
        Collections.sort(choices);
        // 出題
        out.printf("[第%d問] %s%n", qNumber, q.getSentence());
        for (String choice : choices) {
            out.println("    " + choice);
        }
        out.println();
        String choicedNumber;
        while (true) {
            choicedNumber = readLine("答え > ").toUpperCase();
            if (numbers.contains(choicedNumber)) {
                break;
            }
            out.println("正しい選択肢を入力してください。");
        }
        boolean correct = choicedNumber.equals(correctNumber);
        out.println(correct ? "正解!!!" : "不正解!!!");
        out.println();
        out.println();
        return correct;
    }

    static String readLine(String fmt, Object... args) {
        out.printf(fmt, args);
        @SuppressWarnings("resource")
        Scanner scanner = new Scanner(System.in);
        return scanner.nextLine();
    }

    static List<Question> readQuestions(String... paths) {
        List<Question> a = new ArrayList<>();
        for (String pathString : paths) {
            Path path = Paths.get(pathString);
            if (!Files.isRegularFile(path)) {
                out.printf("  警告: ファイル[%s]は見つかりません。%n%n", path);
                continue;
            }
            Queue<String> lines;
            try {
                lines = new LinkedList<>(Files.readAllLines(path, StandardCharsets.UTF_8));
            } catch (IOException e) {
                out.printf("  警告: ファイル[%s]読み取り中にエラーが発生しました。 (%s)%n%n", path, e);
                continue;
            }
            while (!lines.isEmpty()) {
                String sentence = lines.poll();
                String correctAnswer = lines.poll();
                List<String> wrongAnswers = new ArrayList<>();
                while (true) {
                    if (lines.isEmpty()) {
                        break;
                    }
                    final String line = lines.poll();
                    if (line.matches("\\s*")) {
                        break;
                    }
                    wrongAnswers.add(line);
                }
                if (sentence == null || correctAnswer == null || wrongAnswers.isEmpty()) {
                    out.printf("  警告: ファイル[%s]の途中の不正なフォーマットをスキップします。%n%n", path);
                }
                else {
                    a.add(new Question(sentence, correctAnswer, wrongAnswers));
                }
            }
        }
        return a;
    }

}

class Question {

    private final String sentence;
    private final String correctAnswer;
    private final List<String> wrongAnswers;

    public Question(String sentence, String correctAnswer, String... wrongAnswers) {
        this(sentence, correctAnswer, Arrays.asList(wrongAnswers));
    }

    public Question(String sentence, String correctAnswer, List<String> wrongAnswers) {
        this.sentence = sentence;
        this.correctAnswer = correctAnswer;
        this.wrongAnswers = wrongAnswers;
    }

    public String getSentence() {
        return sentence;
    }

    public String getCorrectAnswer() {
        return correctAnswer;
    }

    public List<String> getWrongAnswers() {
        return wrongAnswers;
    }

}