import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Date;

public class test {
    /**
     * 获取过去或者未来 任意天内的日期数组
     * @param intervals      intervals天内
     * @return              日期数组
     */
    public static ArrayList<String> test(int intervals ) {
        ArrayList<String> pastDaysList = new ArrayList<>();
        ArrayList<String> fetureDaysList = new ArrayList<>();
        for (int i = 1; i <intervals; i++) {
            pastDaysList.add(getPastDate(i));
//            fetureDaysList.add(getFetureDate(i));
        }
        System.out.println(pastDaysList);
//        System.out.println(fetureDaysList);
        return pastDaysList;
    }
    /**
     * 获取过去第几天的日期
     *
     * @param past
     * @return
     */
    public static String getPastDate(int past) {
        Calendar calendar = Calendar.getInstance();
        calendar.set(Calendar.DAY_OF_YEAR, calendar.get(Calendar.DAY_OF_YEAR) - past);
        Date today = calendar.getTime();
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
        String result = format.format(today);
        return result;
    }
    /**
     * 获取未来 第 past 天的日期
     * @param past
     * @return
     */
    public static String getFetureDate(int past) {
        Calendar calendar = Calendar.getInstance();
        calendar.set(Calendar.DAY_OF_YEAR, calendar.get(Calendar.DAY_OF_YEAR) + past);
        Date today = calendar.getTime();
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
        String result = format.format(today);
        return result;
    }

    public static void main(String[] args){
        test.test(7);
    }

}