Java输入日期判断星期几

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package nn;

import java.util.*;
//import java.lang.*;

public class mm{
	public static boolean judgeYear(int year) {
		if (year % 400 == 0)
			return true;
		else if ((year % 4 == 0) && (year % 100 != 0))
			return true;
		else
			return false;
	}

	public static int getWeekOfDate(int year, int month, int day) {
		int week = -1;
		int[] monthDay = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
		boolean isLeapYear = false;
		int sumDay = 0;
		if (year >= 1900) {
			for (int i = 1900; i < year; i++) {
				if (judgeYear(i))
					sumDay += 366;
				else
					sumDay += 365;
			}
			for (int i = 0; i < month - 1; i++) {
				sumDay += monthDay[i];
			}
			if (month > 2) {
				isLeapYear = judgeYear(year);
				if (isLeapYear)
					sumDay++;
			}
			sumDay += day;

			week = sumDay % 7;
		}
		return week;
	}

	public static String convert(int week) {
		String[] weekName = { "星期天", "星期一", "星期二", "星期三", "星期四", "星期五", "星期六" };
		return weekName[week];
	}

	public static void main(String[] args) {
		int year, month, day;
		Scanner sc = new Scanner(System.in);
		while (true) {

			System.out.println("请输入年:以0结束");
			year = sc.nextInt();
			if (year == 0) {
				System.out.println("结束！");
				sc.close();
				return;
			}

			if (year < 1900) {
				System.out.println("请输入1900以后的年份");
				continue;
			}

			System.out.println("请输入月:");
			month = sc.nextInt();
			while (month > 12 || month < 1) {
				System.out.println("请输入1-12间的月份");
			}
			System.out.println("请输入日:");
			day = sc.nextInt();
			while (!(day > 0 && day < 32)) {
				System.out.println("请输入1号到31号间的日期");
			}
			System.out.println();
			int week = getWeekOfDate(year, month, day);
			System.out.println(convert(week));
			System.out.println();

		}

	}
}