feat: Add java baseball game

.java-version

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+17

README.md

@@ -1 +1,37 @@
-# java-baseball-precourse
+# 숫자 야구 게임
+
+## 프로젝트 개요
+1부터 9까지 서로 다른 숫자로 이루어진 3자리 수를 맞추는 숫자 야구 게임이다.
+컴퓨터가 임의의 숫자 3개를 생성하고, 사용자는 숫자를 입력해 힌트를 받으며 정답을 맞힌다.
+모든 숫자를 맞히면 게임이 종료되며, 이후 재시작 또는 종료를 선택할 수 있다.
+
+간단한 흐름
+- 숫자 입력 → 힌트 출력(스트라이크/볼/낫싱) → 정답 시 종료 메시지 출력 → 재시작/종료 선택
+
+## 구현(레이어드) 체크리스트
+### Domain
+- [x] ComputerNumbers: 1~9 서로 다른 숫자 3개 생성
+- [x] ComputerNumbersTest: 범위/중복 생성 검증
+- [x] PlayerNumbers: 입력 파싱 및 검증(길이/숫자/범위/중복)
+- [x] PlayerNumbersTest: 파싱 및 예외 케이스 검증
+- [x] Judgement: 스트라이크/볼 계산
+- [x] JudgementTest: 스트라이크/볼/낫싱 케이스 검증
+- [x] HintResult: 판정 결과 값 객체(스트라이크/볼/낫싱)
+- [x] HintResultTest: 결과 값 객체 규칙 검증
+
+### Application
+- [x] GameService: 정답 생성과 판정 흐름 연결
+- [x] GameService: 3스트라이크 종료 판단
+- [x] GameService: 재시작/종료 분기 처리
+
+### UI
+- [x] InputView: 숫자 입력, 재시작 선택 입력
+- [x] OutputView: 힌트/종료 메시지 출력
+- [x] ErrorHandler: `[ERROR]` 메시지 출력 후 진행 유지
+
+## 제약사항
+- indent depth 2 이하
+- `else`/`switch` 미사용
+- 메서드 길이 15라인 이하
+- Stream API 미사용(람다 가능)
+- 도메인 로직과 UI 로직 분리

src/main/java/baseball/BaseballApplication.java

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+package baseball;
+
+import baseball.application.GameService;
+import baseball.domain.exceptions.BaseballException;
+import baseball.domain.models.ComputerNumbers;
+import baseball.domain.models.HintResult;
+import baseball.domain.models.PlayerNumbers;
+import baseball.ui.ErrorHandler;
+import baseball.ui.InputView;
+import baseball.ui.OutputView;
+
+public class BaseballApplication {
+	private final GameService gameService;
+	private final InputView inputView;
+	private final OutputView outputView;
+	private final ErrorHandler errorHandler;
+
+	public BaseballApplication() {
+		this(new GameService(new ComputerNumbers()), new InputView(), new OutputView(), new ErrorHandler());
+	}
+
+	public BaseballApplication(GameService gameService, InputView inputView, OutputView outputView,
+		ErrorHandler errorHandler) {
+		this.gameService = gameService;
+		this.inputView = inputView;
+		this.outputView = outputView;
+		this.errorHandler = errorHandler;
+	}
+
+	public static void main(String[] args) {
+		new BaseballApplication().run();
+	}
+
+	public void run() {
+		gameService.startNewGame();
+		playLoop();
+	}
+
+	private void playLoop() {
+		while (true) {
+			HintResult result = playRound();
+			if (!gameService.isGameOver(result)) {
+				continue;
+			}
+			outputView.printGameOver();
+			if (restartGame()) {
+				gameService.startNewGame();
+				continue;
+			}
+			return;
+		}
+	}
+
+	private HintResult playRound() {
+		PlayerNumbers playerNumbers = readPlayerNumbers();
+		HintResult result = gameService.judge(playerNumbers);
+		outputView.printHint(result);
+		return result;
+	}
+
+	private PlayerNumbers readPlayerNumbers() {
+		while (true) {
+			outputView.printInputPrompt();
+			try {
+				return PlayerNumbers.from(inputView.readNumbers());
+			} catch (BaseballException exception) {
+				errorHandler.printError(exception);
+			}
+		}
+	}
+
+	private boolean restartGame() {
+		while (true) {
+			outputView.printRestartPrompt();
+			try {
+				return gameService.shouldRestart(inputView.readRestartOption());
+			} catch (BaseballException exception) {
+				errorHandler.printError(exception);
+			}
+		}
+	}
+}

src/main/java/baseball/application/GameService.java

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+package baseball.application;
+
+import java.util.List;
+
+import baseball.domain.exceptions.GameNotStartedException;
+import baseball.domain.exceptions.InvalidRestartOptionException;
+import baseball.domain.models.ComputerNumbers;
+import baseball.domain.models.HintResult;
+import baseball.domain.models.Judgement;
+import baseball.domain.models.PlayerNumbers;
+
+public class GameService {
+	private final ComputerNumbers computerNumbers;
+	private List<Integer> answerNumbers;
+
+	public GameService(ComputerNumbers computerNumbers) {
+		this.computerNumbers = computerNumbers;
+	}
+
+	public void startNewGame() {
+		answerNumbers = computerNumbers.generate();
+	}
+
+	public HintResult judge(PlayerNumbers playerNumbers) {
+		validateStarted();
+		Judgement judgement = new Judgement(answerNumbers, playerNumbers.numbers());
+		return new HintResult(judgement.countStrike(), judgement.countBall());
+	}
+
+	public boolean isGameOver(HintResult hintResult) {
+		return hintResult.strikeCount() == 3;
+	}
+
+	public boolean shouldRestart(String input) {
+		validateRestartOption(input);
+		return isRestartOption(input);
+	}
+
+	private void validateStarted() {
+		if (answerNumbers != null) {
+			return;
+		}
+		throw new GameNotStartedException("게임을 먼저 시작해주세요.");
+	}
+
+	private void validateRestartOption(String input) {
+		if (input == null) {
+			throw new InvalidRestartOptionException();
+		}
+		if (isRestartOption(input)) {
+			return;
+		}
+		if (isExitOption(input)) {
+			return;
+		}
+		throw new InvalidRestartOptionException();
+	}
+
+	private boolean isRestartOption(String input) {
+		return "1".equals(input);
+	}
+
+	private boolean isExitOption(String input) {
+		return "2".equals(input);
+	}
+}

src/main/java/baseball/domain/exceptions/BaseballException.java

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+package baseball.domain.exceptions;
+
+public class BaseballException extends IllegalArgumentException {
+	private static final String ERROR_PREFIX = "[ERROR] ";
+
+	public BaseballException(String message) {
+		super(ERROR_PREFIX + message);
+	}
+}

src/main/java/baseball/domain/exceptions/GameNotStartedException.java

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+package baseball.domain.exceptions;
+
+public class GameNotStartedException extends BaseballException {
+	public GameNotStartedException(String message) {
+		super(message);
+	}
+}

src/main/java/baseball/domain/exceptions/InvalidHintResultException.java

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+package baseball.domain.exceptions;
+
+public class InvalidHintResultException extends BaseballException {
+	public InvalidHintResultException(String message) {
+		super(message);
+	}
+}

src/main/java/baseball/domain/exceptions/InvalidPlayerNumbersException.java

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+package baseball.domain.exceptions;
+
+public class InvalidPlayerNumbersException extends BaseballException {
+	public InvalidPlayerNumbersException(String message) {
+		super(message);
+	}
+}

src/main/java/baseball/domain/exceptions/InvalidRestartOptionException.java

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+package baseball.domain.exceptions;
+
+public class InvalidRestartOptionException extends BaseballException {
+	private static final String MESSAGE = "재시작은 1, 종료는 2를 입력해주세요.";
+
+	public InvalidRestartOptionException() {
+		super(MESSAGE);
+	}
+}

src/main/java/baseball/domain/models/ComputerNumbers.java

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+package baseball.domain.models;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Random;
+
+public class ComputerNumbers {
+	private final Random random;
+
+	public ComputerNumbers() {
+		this(new Random());
+	}
+
+	public ComputerNumbers(Random random) {
+		this.random = random;
+	}
+
+	public List<Integer> generate() {
+		List<Integer> numbers = new ArrayList<>();
+		while (numbers.size() < 3) {
+			int candidate = random.nextInt(9) + 1;
+			if (numbers.contains(candidate)) {
+				continue;
+			}
+			numbers.add(candidate);
+		}
+		return numbers;
+	}
+}

src/main/java/baseball/domain/models/HintResult.java

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+package baseball.domain.models;
+
+import baseball.domain.exceptions.InvalidHintResultException;
+
+public class HintResult {
+	private static final int MAX_COUNT = 3;
+	private static final String NOTHING_MESSAGE = "낫싱";
+	private static final String STRIKE_SUFFIX = "스트라이크";
+	private static final String BALL_SUFFIX = "볼";
+
+	private final int strikeCount;
+	private final int ballCount;
+
+	public HintResult(int strikeCount, int ballCount) {
+		validateCount(strikeCount);
+		validateCount(ballCount);
+		validateTotal(strikeCount, ballCount);
+		this.strikeCount = strikeCount;
+		this.ballCount = ballCount;
+	}
+
+	public int strikeCount() {
+		return strikeCount;
+	}
+
+	public int ballCount() {
+		return ballCount;
+	}
+
+	public String message() {
+		if (strikeCount == 0 && ballCount == 0) {
+			return NOTHING_MESSAGE;
+		}
+		StringBuilder builder = new StringBuilder();
+		appendCount(builder, strikeCount, STRIKE_SUFFIX);
+		appendCount(builder, ballCount, BALL_SUFFIX);
+		return builder.toString();
+	}
+
+	private void appendCount(StringBuilder builder, int count, String suffix) {
+		if (count == 0) {
+			return;
+		}
+		if (builder.length() > 0) {
+			builder.append(" ");
+		}
+		builder.append(count).append(suffix);
+	}
+
+	private void validateCount(int count) {
+		if (count < 0 || count > MAX_COUNT) {
+			throw new InvalidHintResultException("카운트는 0에서 3 사이여야 해요.");
+		}
+	}
+
+	private void validateTotal(int strikeCount, int ballCount) {
+		if (strikeCount + ballCount > MAX_COUNT) {
+			throw new InvalidHintResultException("스트라이크와 볼의 합은 3을 넘을 수 없어요.");
+		}
+	}
+}

src/main/java/baseball/domain/models/Judgement.java

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+package baseball.domain.models;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class Judgement {
+	private final List<Integer> computerNumbers;
+	private final List<Integer> playerNumbers;
+
+	public Judgement(List<Integer> computerNumbers, List<Integer> playerNumbers) {
+		this.computerNumbers = new ArrayList<>(computerNumbers);
+		this.playerNumbers = new ArrayList<>(playerNumbers);
+	}
+
+	public int countStrike() {
+		int strikes = 0;
+		for (int index = 0; index < playerNumbers.size(); index++) {
+			if (isStrike(index)) {
+				strikes++;
+			}
+		}
+		return strikes;
+	}
+
+	public int countBall() {
+		int balls = 0;
+		for (int index = 0; index < playerNumbers.size(); index++) {
+			if (isStrike(index)) {
+				continue;
+			}
+			if (computerNumbers.contains(playerNumbers.get(index))) {
+				balls++;
+			}
+		}
+		return balls;
+	}
+
+	private boolean isStrike(int index) {
+		return playerNumbers.get(index).equals(computerNumbers.get(index));
+	}
+}