Test4.java

/*
 * 김소은
 * 과제4. 주민등록번호 생성 프로그램
 *
 * 주민등록과 관련된 변수, 함수를 묶어 클래스를 만들었습니다.
 * 주민등록번호 생성 가능한 날짜는 1900년 1월 1일부터 프로그램을 실행하는 당일까지 가능하도록 구현하였습니다.
 * 입력값이 잘못됐으면 재입력할 수 있도록 구현하였습니다.
 */

import java.time.LocalDate;
import java.util.InputMismatchException;
import java.util.Random;
import java.util.Scanner;

class ResidentRegistration {
	private int birthYear;
	private int birthMonth;
	private int birthDay;
	private char gender;

	public static void checkValidRegistrationYear(int year) {
		int thisYear = LocalDate.now().getYear();
		if (year < 1900 || year > thisYear) {
			throw new InputMismatchException(String.format("1900 ~ %d 사이의 값만 등록 가능합니다.", thisYear));
		}
	}

	public static void checkValidRegistrationMonth(int month) {
		if (month < 1 || month > 12) {
			throw new InputMismatchException("1 ~ 12 사이의 값만 가능합니다.");
		}
	}

	public static void checkValidRegistrationMonth(int month, int monthLimit) {
		if (month < 1 || month > monthLimit) {
			throw new InputMismatchException(String.format("해당 년도에 등록 가능한 달은 1 ~ %d 입니다.", monthLimit));
		}
	}

	public static void checkValidRegistrationDay(int day, int dayLimit) {
		if (day < 1 || day > dayLimit) {
			throw new InputMismatchException(String.format("해당 년도와 월에 등록 가능한 날은 1 ~ %d 입니다.", dayLimit));
		}
	}

	public static void checkValidGender(char gender) {
		if (gender != 'm' && gender != 'f') {
			throw new InputMismatchException("m 또는 f만 입력 가능합니다.");
		}
	}

	public ResidentRegistration(int birthYear, int birthMonth, int birthDay, char gender) {
		this.birthYear = birthYear;
		this.birthMonth = birthMonth;
		this.birthDay = birthDay;
		this.gender = gender;
	}

	public String makeNumber() {
		StringBuilder residentRegistrationNumber = new StringBuilder();

		int twoDigitBirthYear = birthYear % 100;
		residentRegistrationNumber.append(String.format("%02d%02d%02d", twoDigitBirthYear, birthMonth, birthDay));

		residentRegistrationNumber.append('-');

		residentRegistrationNumber.append(getGenderNumber(birthYear, gender));
		residentRegistrationNumber.append(getRandomNumber(6));

		return residentRegistrationNumber.toString();
	}

	private int getGenderNumber(int birthYear, char gender) {
		if (gender == 'm') {
			if (birthYear < 2000) {
				return 1;
			} else {
				return 3;
			}
		} else if (gender == 'f') {
			if (birthYear < 2000) {
				return 2;
			} else {
				return 4;
			}
		} else {
			throw new IllegalArgumentException("성별의 입력값이 올바르지 않습니다.");
		}
	}

	private String getRandomNumber(int digit) {
		Random random = new Random();
		StringBuilder randomNumber = new StringBuilder();

		for (int i = 0; i < digit; i++) {
			randomNumber.append(random.nextInt(10));
		}

		return randomNumber.toString();
	}
}

public class Test4 {
	private static final Scanner scanner = new Scanner(System.in);

	public static void main(String[] args) {
		System.out.println("[주민등록번호 계산]");

		ResidentRegistration residentRegistration = inputResidentRegistration();

		String residentRegistrationNumber = residentRegistration.makeNumber();
		System.out.println(residentRegistrationNumber);

		closeResource();
	}

	private static ResidentRegistration inputResidentRegistration() {
		int birthYear = inputBirthYear();

		int birthMonth;
		if (birthYear == LocalDate.now().getYear()) {	// 생일이 올해라면 현재 달까지만 등록 가능
			int monthLimit = LocalDate.now().getMonthValue();
			birthMonth = inputBirthMonth(monthLimit);
		} else {
			birthMonth = inputBirthMonth();
		}

		int dayLimit;
		if (birthYear == LocalDate.now().getYear() && birthMonth == LocalDate.now().getMonthValue()) {	// 생일이 올해 이번 달이라면 현재 날짜까지만 등록 가능
			dayLimit = LocalDate.now().getDayOfMonth();
		} else {
			dayLimit = LocalDate.of(birthYear, birthMonth, 1).lengthOfMonth();
		}
		int birthDay = inputBirthDay(dayLimit);
		
		char gender = inputGender();

		return new ResidentRegistration(birthYear, birthMonth, birthDay, gender);
	}

	private static int inputBirthYear() {
		int birthYear = 0;
		boolean isValid = false;

		while (! isValid) {
			System.out.print("출생년도를 입력해 주세요.(yyyy):");

			try {
				checkIntType();

				birthYear = scanner.nextInt();
				ResidentRegistration.checkValidRegistrationYear(birthYear);

				isValid = true;
			} catch (InputMismatchException e) {
				System.out.println(e.getMessage());
			}
		}

		return birthYear;
	}

	private static int inputBirthMonth() {
		int birthMonth = 0;
		boolean isValid = false;

		while (! isValid) {
			System.out.print("출생월을 입력해 주세요.(mm):");

			try {
				checkIntType();

				birthMonth = scanner.nextInt();
				ResidentRegistration.checkValidRegistrationMonth(birthMonth);

				isValid = true;
			} catch (InputMismatchException e) {
				System.out.println(e.getMessage());
			}
		}

		return birthMonth;
	}

	private static int inputBirthMonth(int monthLimit) {
		int birthMonth = 0;
		boolean isValid = false;

		while (! isValid) {
			System.out.print("출생월을 입력해 주세요.(mm):");

			try {
				checkIntType();

				birthMonth = scanner.nextInt();
				ResidentRegistration.checkValidRegistrationMonth(birthMonth, monthLimit);

				isValid = true;
			} catch (InputMismatchException e) {
				System.out.println(e.getMessage());
			}
		}

		return birthMonth;
	}

	private static int inputBirthDay(int dayLimit) {
		int birthDay = 0;
		boolean isValid = false;

		while (! isValid) {
			System.out.print("출생일을 입력해 주세요.(dd):");

			try {
				checkIntType();

				birthDay = scanner.nextInt();
				ResidentRegistration.checkValidRegistrationDay(birthDay, dayLimit);

				isValid = true;
			} catch (InputMismatchException e) {
				System.out.println(e.getMessage());
			}
		}

		return birthDay;
	}

	private static char inputGender() {
		char gender = '-';
		boolean isValid = false;

		while (! isValid) {
			System.out.print("성별을 입력해 주세요.(m/f):");

			try {
				gender = scanner.next().charAt(0);
				ResidentRegistration.checkValidGender(gender);

				isValid = true;
			} catch (InputMismatchException e) {
				System.out.println(e.getMessage());
			}
		}

		return gender;
	}

	private static void checkIntType() {
		if (! scanner.hasNextInt()) {
			removeBuffer();
			throw new InputMismatchException("숫자만 입력 가능합니다.");
		}
	}

	private static void removeBuffer() { scanner.next(); }

	private static void closeResource() { scanner.close(); }
}