技術標籤：java

根據任意某天，獲取所在一週日期, 星期

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.*;
import java.util.stream.Collectors;

/**
 * @author : 秦淮
 * create at:  2021/1/14  10:27
 * @description: 獲取當前日期所在一週日期, 星期
 */
public class GetDateWeek {
    public static void main(String[
 
] args) throws ParseException {
        Date date = new Date();
        
        // 測試
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
        date = sdf.parse("2020-12-31");
        
        Map<Date, String> map = getAllDateOfWeek(date);
        for (Date d :
 
 map.keySet()) {
            System.out.println("日期：" + d + ",星期：" + map.get(d));
        }
    }

    /**
     * 獲取當前日期所在一週日期, 星期
     *
     * @param date Date
     * @return Map<Date, String> key:日期 value 星期
     */
    public static Map<Date, String> getAllDateOfWeek
 
(Date date) {
        Map<Date, String> mapWeek = new HashMap<>(16);
        Calendar cal = Calendar.getInstance();
        cal.setTime(date);

        //若是星期日，則減一天
        if(1 == cal.get(Calendar.DAY_OF_WEEK)) {
            cal.add(Calendar.DAY_OF_MONTH, -1);
        }
        cal.setFirstDayOfWeek(Calendar.MONDAY);
        int day = cal.get(Calendar.DAY_OF_WEEK);
        cal.add(Calendar.DATE, cal.getFirstDayOfWeek() - day);

        String[] weeks = {"", "星期日", "星期一", "星期二", "星期三", "星期四", "星期五", "星期六"};
        for(int i = 1; i <= 7; i++){
            int number = cal.get(Calendar.DAY_OF_WEEK);
            mapWeek.put(cal.getTime(), weeks[number]);
            cal.add(Calendar.DATE, 1);
        }
        Map<Date, String> sortMap = mapWeek.entrySet().stream().sorted(Map.Entry.comparingByKey()).collect(
                Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue,
                        (oleValue, newValue) -> oleValue, LinkedHashMap::new));
        return sortMap;
    }
}

獲取月份的每一天及星期
https://blog.csdn.net/weixin_42919267/article/details/112321634