代码执行后与想要的答案不一致

Question

package day01;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.Scanner;

public class Test01 {
public static void main(String[] args) throws ParseException {
System.out.println("请输入生产日期：");
Scanner in=new Scanner(System.in);
String date=in.nextLine();
System.out.println("请输入保质日期：");
int day=in.nextInt();

System.out.println("促销时间是："+getDate(date,day));
in.close();

}
public static String getDate(String date,int day) throws ParseException{
SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");
Date dat=sdf.parse(date);
Calendar calendar=Calendar.getInstance();
calendar.setTime(dat);
calendar.add(Calendar.DAY_OF_YEAR, day);
calendar.add(Calendar.WEEK_OF_YEAR, -2);
calendar.add(Calendar.DAY_OF_WEEK, 4);

String dates=sdf.format(calendar.getTime());
return dates;

}
}