根据年月日算出星期几(欢迎批评)

           Scanner xq=new Scanner(System.in);
			System.out.print("请输入年:");
		    int year=xq.nextInt();
			System.out.println("---------------------");
			System.out.print("请输入月:");
		    int mon=xq.nextInt();
			System.out.println("---------------------");
			System.out.print("请输入日:");
		    int day=xq.nextInt();
			System.out.println("---------------------");
			int allday;  //存储全部天数
			allday=year*365;   //把年换算成天
			allday=allday+(year/4);//加上闰年多出来的天
			if(mon==2){      //以下是把月换算成天
				allday=allday+31;
			}
			else if(mon==3){
				allday=allday+59;
			}
			else if(mon==4){
				allday=allday+90;
			}
			else if(mon==5){
				allday=allday+120;
			}
			else if(mon==6){
				allday=allday+151;
			}
			else if(mon==7){
				allday=allday+181;
			}
			else if(mon==8){
				allday=allday+212;
			}
			else if(mon==9){
				allday=allday+243;
			}
			else if(mon==10){
				allday=allday+273;
			}
			else if(mon==11){
				allday=allday+304;
			}
			else if(mon==12){
				allday=allday+334;
			}
			allday=allday+day;     //直接加上刚才输入的天数
			int xx1;         //存储是星期几
			xx1=(allday%7)-2;
			if(xx1==-2){
				xx1=5;
			}
			else if(xx1==-1){
				xx1=6;
			}
			else if(xx1==0){
				xx1=7;
			}
			System.out.println("星期"+xx1);