java 获取本周日期、上周日期、下周日期

//日期实体
class PlanBean {
    var date: String? = ""
    var week: String? = ""
    var day: String? = ""
}

    public static String getWeek(int week) {
        switch (week) {
            case 1:
                return "周日";
            case 2:
                return "周一";
            case 3:
                return "周二";
            case 4:
                return "周三";
            case 5:
                return "周四";
            case 6:
                return "周五";
            case 7:
                return "周六";
        }
        return "";
    }

  		Calendar calendar = Calendar.getInstance();
  		//设置周一为每周第一天
        calendar.setFirstDayOfWeek(Calendar.MONDAY);
        //设置当前日期为本周的周一
        calendar.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);

	//获取日期列表
    private void loadWeekList() {
        listData.clear();
        for (int i = 0; i < 7; i++) {
            int year = calendar.get(Calendar.YEAR);
            int month = calendar.get(Calendar.MONTH) + 1;
            int day = calendar.get(Calendar.DAY_OF_MONTH);
            int week = calendar.get(Calendar.DAY_OF_WEEK);
            PlanBean planBean = new PlanBean();
            planBean.setDate(year + "-" + month + "-" + day);
            String weeks = getWeek(week);
            planBean.setWeek(weeks);
            planBean.setDay("" + day);
            listData.add(planBean);
            if (i == 6) {
//                设置玩数据重置日期为当前周一
                calendar.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
            } else {
            	//日期递增
                calendar.add(Calendar.DATE, 1);
            }
        }
     }

    /**
     *  0 本周
     * -1 上一周
     * +1 下一周
     *
     * @param next 下一个
     */
    public void UpWeek(int next) {
       	//日期+7/-7
        calendar.add(Calendar.DATE, next * 7);
        loadWeekList();
    }