Java任意输入年月日并判断这天是星期几

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;import java.util.Scanner;
public class Datetest{
	public static void main(String[] args){
		System.out.println("请输入三个以内的数字，并以#结束：");
		Scanner input = new Scanner(System.in);
		String str="";
		StringBuffer sb = new StringBuffer();
		Calendar calendar = Calendar.getInstance();
		String weekd = "日一二三四五六";
		while(!(str=input.next()).equals("#")){
			sb.append(str+";");
		}
		String subs=sb.toString();
		String[] arr = subs.split(";");
		if(arr.length!=3){
			System.out.println("输入数据错误！");
		}
		else{
			String date = arr[0]+"-"+arr[1]+"-"+arr[2];
			SimpleDateFormat f = new SimpleDateFormat("yyyy-MM-dd");
			Date datet = null;
			try {
				datet = f.parse(date);
			} catch (ParseException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			calendar.setTime(datet);
			int day = calendar.get(Calendar.DAY_OF_WEEK);
			System.out.println("这天是星期"+weekd.substring(day-1,day));
		}
	}
}