= 실행코드 =
{{{~cpp code
import javax.swing.JOptionPane;
public class BaseBall {	
	private int correctNumber;
	public static void main(String[] args) {
		BaseBall oneGame = new BaseBall();
		oneGame.setCorrectNumber();
		int guess = 0, result = 0;
		do
		{
			guess = oneGame.inputGuess();
			result = oneGame.compare(guess);
			if (result != 30)
				JOptionPane.showMessageDialog(null, (result / 10) + " Strike, " 
						+ (result % 10) + " Ball");
		}while (result != 30);
		oneGame.displayResult();
	}
	public void setCorrectNumber()
	{
		int setNumber = 0;
		do
		{
			setNumber = (int) (Math.random() * 10);
		}while (setNumber == 0);
		correctNumber = setNumber;
		do
		{
			setNumber = (int) (Math.random() * 10);
		}while (correctNumber == setNumber);
		correctNumber = correctNumber * 10 + setNumber;
		do
		{
			setNumber = (int) (Math.random() * 10);
		}while (((int)(correctNumber / 10)) == setNumber 
				|| ((int)(correctNumber % 10)) == setNumber);
		correctNumber = correctNumber * 10 + setNumber;
	}
	public int inputGuess()
	{
		String input =  JOptionPane.showInputDialog("Enter three different number\n");
		int guess = Integer.parseInt(input);
		return guess;
	}
	public int compare(int aGuess)
	{
		int compareResult = 0, cCorrect = correctNumber;
		int firstGuess = (int) (aGuess / 100);
		int secondGuess = ((int) (aGuess / 10)) % 10;
		int thirdGuess = aGuess % 10;
		if (((int)(cCorrect / 100) == firstGuess))
				compareResult ++;
		cCorrect = cCorrect % 100;
		if (((int)(cCorrect / 10) == secondGuess))
				compareResult ++;
		cCorrect = cCorrect % 10;
		if (cCorrect == thirdGuess)
				compareResult ++;
		compareResult *= 10;
		cCorrect = correctNumber;
		if (((int)(cCorrect / 100)) == secondGuess 
				|| ((int)(cCorrect / (100))) == thirdGuess)
			compareResult ++;
		cCorrect = cCorrect % 100;
		if (((int)(cCorrect / 10)) == firstGuess 
				|| ((int)(cCorrect / (10))) == thirdGuess)
			compareResult ++;
		cCorrect = cCorrect % 10;
		if ((cCorrect == firstGuess) || (cCorrect == secondGuess))
			compareResult ++;
		return compareResult;
	}
	public void displayResult()
	{
		JOptionPane.showMessageDialog(null, "You are right!\n Answer is " + correctNumber);
	}
}
}}}
= 잡담 =
 * 정답을 int변수 3자리 숫자로 표현해서 만들어봤더니 코드만 더 길어졌네요 -0-;; - [문원명]






= 개선 시도 =
집에서 놀다가 우연히 여기를 와서 고쳐봅니다. 조금 더 생각해 보시면 되지요. 저에게 재미있는 경험을 주었는데, 문원명 후배님도 보시라고 과정을 만들어 두었습니다.  선행학습으로 JUnit이 있어야 하는데, http://junit.org 에서 궁금하시면 [http://www.devx.com/Java/Article/31983/0/page/2 관련문서]를 보시고 선배들에게 물어보세요. 

용기가 내셔서 저를 찾으면... ;; 
--NeoCoin
 * 처음에는 Test-Driven Development 에 입각하여 만들어 보려고 했으나, Java를 거의 처음 시작하고 프로그래밍 경험의 공백기간이 길었던게 큰 타격이었습니다ㅠㅠ. 결국에는 문법과 알고리즘에만 신경을 쓰다보니 TDD방식으로 다루기가 쉽지 않네요. 개선 조언을 해 주신 류상민 선배님 감사합니다 ㅎㅎ -[문원명]
   * 오해가 있을 것 같아서 코멘트 합니다. TDD는 별로 중요하지 않습니다. 결정적으로 저는 '''TDD로 하지 않았습니다.''' 그냥 Refactoring시 Regression Test를 위해서 JUnit 을 썼을 뿐이에요.--NeoCoin
    *  네, 제가 TDD의 의미를 확실히 하지 못한 것 같습니다. TDD책의 앞부분만 읽어 보았는데, 계속해서 더 읽어야 나가야겠다는 다짐이 드네요. 관심 가져주셔서 고맙습니다 ㅋ -[문원명]
== 과정 ==
초기의 테스트 가능하도록 원하는 값으로 무작위로 나오는 답안을 세팅하는 함수 추가.
{{{~java
// ..생략
	void setCorrectNumber(int in) {
		correctNumber = in;
	}

	@Test
	public void test2() {
		BaseBall oneGame = new BaseBall();
		oneGame.setCorrectNumber(123);
		assertEquals(30, oneGame.compare(123));
		assertEquals(10, oneGame.compare(100, 123));
		assertEquals(2, oneGame.compare(310, 123));
	}
//..생략
}}}

setCorrectNumber 하기도 귀찮아서 compare 부분을 확장 , 내부에서 쓰일일이 없는 함수로 제거 목적으로 코스 수정
{{{~java
	@Test
	public void test2() {
		BaseBall oneGame = new BaseBall();
		assertEquals(30, oneGame.compare(123, 123));
		assertEquals(10, oneGame.compare(100, 123));
		assertEquals(2, oneGame.compare(310, 123));
	}

	public int compare(int aGuess) {
		return compare(aGuess, correctNumber);
	}
	public int compare(int aGuess, int answer) {
		correctNumber = answer;

		int compareResult = 0, cCorrect = correctNumber;
//생략
	}
}}}

readability 를 위해 필요없는 typecasting 문법들 제거 (Java Language Specification의 규칙들을 보세요. 해당 typecasting은 거의다 필요 없는겁니다.) 유의미한 단위로 분리
{{{~java
	public int compare(int aGuess, int answer) {
		correctNumber = answer;

		int compareResult = 0, cCorrect = correctNumber;
		int firstGuess = aGuess / 100 % 10;
		int secondGuess = aGuess / 10 % 10;
		int thirdGuess = aGuess % 10;



		if (cCorrect / 100 == firstGuess)
			compareResult++;
		cCorrect = cCorrect % 100;
		if (cCorrect / 10 == secondGuess)
			compareResult++;
		cCorrect = cCorrect % 10;
		if (cCorrect == thirdGuess)
			compareResult++;
		compareResult *= 10;



		cCorrect = correctNumber;
		if ((cCorrect / 100) == secondGuess || (cCorrect / 100) == thirdGuess)
			compareResult++;
		cCorrect = cCorrect % 100;
		if ((cCorrect / 10) == firstGuess || (cCorrect / 10) == thirdGuess)
			compareResult++;
		cCorrect = cCorrect % 10;
		if ((cCorrect == firstGuess) || (cCorrect == secondGuess))
			compareResult++;
		return compareResult;
	}
}}}
특정 포지션의 숫자를 얻어오기 위한 반복 부분들 발견, 특정 포지션을 얻어오는 함수 만들기
{{{~java
	int positionNum(int value, int pos) {
		if (pos < 1)
			throw new IndexOutOfBoundsException("pos값은 1이상을 넣어주세요.");
		int a = value % (int) Math.pow(10, pos);
		return a / (int) Math.pow(10, pos - 1);
	}

	@Test
	public void getPositionNum() {
		assertEquals(3, positionNum(123, 1));
		assertEquals(2, positionNum(123, 2));
		assertEquals(1, positionNum(123, 3));
	}
}}}

해당 함수를 알고리즘에 적용, Test는 계속 녹색 . 
결과 값을 의미를 드러낼수 있도록 변경
더이상 함수가 this.correctNumber에 의존할 필요 없으므로 코드 개선
{{{~java
public int compare(int aGuess, int cCorrect) {
		int firstGuess = positionNum(aGuess,3);
		int secondGuess = positionNum(aGuess,2);
		int thirdGuess = positionNum(aGuess,1);


		int strike=0;
		if (positionNum(cCorrect,3) == firstGuess)
			strike++;
		if (positionNum(cCorrect,2) == secondGuess)
			strike++;
		if (positionNum(cCorrect,1) == thirdGuess)
			strike++;


		int ball=0;
		if (positionNum(cCorrect,3) == secondGuess || positionNum(cCorrect,3) == thirdGuess)
			ball++;
		if (positionNum(cCorrect,2) == firstGuess || positionNum(cCorrect,2) == thirdGuess)
			ball++;
		if ((positionNum(cCorrect,1) == firstGuess) || (positionNum(cCorrect,1) == secondGuess))
			ball++;
		return ball + strike*10;
	}
}}}
코드에 약간 패턴이 보인다. inline시키면 보일것 같다. 그래서 xxxGuess 를 inline 
{{{~java
public int compare(int aGuess, int answer) {
		int cCorrect = answer;
		int strike=0;
		if (positionNum(cCorrect,3) == positionNum(aGuess,3))
			strike++;
		if (positionNum(cCorrect,2) == positionNum(aGuess,2))
			strike++;
		if (positionNum(cCorrect,1) == positionNum(aGuess,1))
			strike++;


		int ball=0;
		if (positionNum(cCorrect,3) == positionNum(aGuess,2) || positionNum(cCorrect,3) == positionNum(aGuess,1))
			ball++;
		if (positionNum(cCorrect,2) == positionNum(aGuess,3) || positionNum(cCorrect,2) == positionNum(aGuess,1))
			ball++;
		if ((positionNum(cCorrect,1) == positionNum(aGuess,3)) || (positionNum(cCorrect,1) == positionNum(aGuess,2)))
			ball++;
		return ball + strike*10;
	}
}}}

숫자 패턴을 파악하고 중복 개선, magic number 제거
{{{~java
	public int compare(int aGuess, int cCorrect) {
		final int START_POS = 1,END_POS = 3;

		int strike = 0;
		for (int pos = END_POS; pos >=START_POS; pos--) {
			if (positionNum(cCorrect, pos) == positionNum(aGuess, pos))
				strike++;
		}

		int ball = 0;
		for (int corPos = END_POS; corPos >=START_POS; corPos--) {
			for (int guePos = END_POS; guePos > 0; guePos--) {
				if (corPos != guePos && positionNum(cCorrect, corPos) == positionNum(aGuess,guePos))
					ball++;
			}
		}
		return ball + strike * 10;
	}
}}}

두개의 루프의 정확한 의미 파악, 합침
{{{~java
	public int compare(int aGuess, int cCorrect) {
		final int START_POS = 1, END_POS = 3;

		int strike = 0, ball = 0;

		for (int corPos = END_POS; corPos >= START_POS; corPos--) {
			for (int guePos = END_POS; guePos >= START_POS; guePos--) {
				if (positionNum(cCorrect, corPos) == positionNum(aGuess, guePos)) {
					if (corPos == guePos)
						strike++;
					else
						ball++;
				}
			}
		}
		return ball + strike * 10;
	}
}}}

해당 루틴이 지날때 마다 result 값에 10과 1을 더해주는 방식으로 바꿈
{{{~java
	public int compare(int aGuess, int cCorrect) {
		final int START_POS = 1, END_POS = 3, STRIKE_DELTA = 10, BALL_DELTA = 1;

		int result = 0;  //10자리가 strike, 1자리고 ball 값
		for (int corPos = END_POS; corPos >= START_POS; corPos--)
			for (int guePos = END_POS; guePos >= START_POS; guePos--)
				if (positionNum(cCorrect, corPos) == positionNum(aGuess, guePos))
					result += (corPos == guePos) ? STRIKE_DELTA : BALL_DELTA;
		return result;
	}
}}}

기타 overloading된 무의미한 compare를 정리. 소스상 setCorrectNumber를 생성자로 옮김.
더 개선하고 싶으나 그냥 하기 지쳐서 여기서 그만..
{{{~java
package test;

import static org.junit.Assert.assertEquals;
import org.junit.Test;
import javax.swing.JOptionPane;

public class BaseBall {
	private int correctNumber;

	public static void main(String[] args) {
		final int END_GAME_NUM = 30;

		BaseBall oneGame = new BaseBall();
		while (true) {
			int result = oneGame.runOneTurn();
			if (result == END_GAME_NUM)
				break;
			else
				JOptionPane.showMessageDialog(null,
					String.format("%d Strike, %d Ball", result / 10, result % 10));
		}
		oneGame.displayResult();
	}

	public int runOneTurn() {
		return compare(this.correctNumber, inputGuess());
	}

	public BaseBall() {
		int setNumber = 0;
		do {
			setNumber = (int) (Math.random() * 10);
		} while (setNumber == 0);
		correctNumber = setNumber;
		do {
			setNumber = (int) (Math.random() * 10);
		} while (correctNumber == setNumber);
		correctNumber = correctNumber * 10 + setNumber;
		do {
			setNumber = (int) (Math.random() * 10);
		} while (correctNumber / 10 == setNumber
				|| correctNumber % 10 == setNumber);
		correctNumber = correctNumber * 10 + setNumber;
	}

	public int inputGuess() {
		String input = JOptionPane
				.showInputDialog("Enter three different number\n");
		int guess = Integer.parseInt(input);
		return guess;
	}

	int positionNum(int value, int pos) {
		if (pos < 1)
			throw new IndexOutOfBoundsException("pos값은 1이상");
		int a = value % (int) Math.pow(10, pos);
		return a / (int) Math.pow(10, pos - 1);
	}

	public int compare(int aGuess, int cCorrect) {
		final int START_POS = 1, END_POS = 3, STRIKE_DELTA = 10, BALL_DELTA = 1;

		int result = 0; // 10자리가 strike, 1자리가 ball 값
		for (int corPos = END_POS; corPos >= START_POS; corPos--)
			for (int guePos = END_POS; guePos >= START_POS; guePos--)
				if (positionNum(cCorrect, corPos) == positionNum(aGuess, guePos))
					result += (corPos == guePos) ? STRIKE_DELTA : BALL_DELTA;
		return result;
	}

	public void displayResult() {
		JOptionPane.showMessageDialog(null, "You are right!\n Answer is "
				+ correctNumber);
	}

	@Test
	public void getPositionNum() {
		assertEquals(3, positionNum(123, 1));
		assertEquals(2, positionNum(123, 2));
		assertEquals(1, positionNum(123, 3));
	}

	@Test
	public void test2() {
		BaseBall oneGame = new BaseBall();
		assertEquals(30, oneGame.compare(123, 123));
		assertEquals(10, oneGame.compare(100, 123));
		assertEquals(2, oneGame.compare(310, 123));
	}
}
}}}