[JAVA]Calendar01_년,월,일구하기

package com.test03;

import java.util.Scanner;

public class Scanner_Calendar {
	
	static int year, month, date;
	
	public static void main(String[] args) {
		System.out.print("년, 월, 일로 요일 구하기: ");
		Scanner sc = new Scanner(System.in);
		year = sc.nextInt();
		month = sc.nextInt();
		date = sc.nextInt();
				
		Calendar(year, month, date);
		sc.close();

	}
	
	public static void Calendar(int year, int month, int day) {

		
		int sum = (year-1)*365 + (year-1)/4 - (year-1)/100 + (year-1)/400;
		
		for(int i = 0; i<month; i++) {
			switch(i) {
			case 0:
				//sum+=0;
				break;
			case 2:
				if(year%4 ==0 && year%100!=0 || year%400==0) {
					sum+=29;
				} else {
					sum+=28;
				}
				break;
				//sum += year%4 ==0 && year%100!=0 || year%400==0 ? 29:28; 
				//break;
			case 4: 
			case 6:
			case 9:
			case 11:
				sum+=30;
				break;
			default:
				sum+=31;
				break;
			}
		}
		sum+=day;
		
		switch(sum%7) {
		case 0:
			System.out.println("일요일");
			break;
		case 1: 
			System.out.println("월요일");
			break;
		case 2: 
			System.out.println("화요일");
			break;
		case 3: 
			System.out.println("수요일");
			break;
		case 4:
			System.out.println("목요일");
			break;
		case 5: 
			System.out.println("금요일");
			break;
		case 6:
			System.out.println("토요일");
			break;
		}	
	}
}

년, 월, 일로 요일 구하기: 2020 10 20
화요일