当天

private void getNowDate() {
    Calendar calendar = Calendar.getInstance();
    int cYear = calendar.get(Calendar.YEAR);
    int cMonth = calendar.get(Calendar.MONTH) + 1;
    int cDay = calendar.get(Calendar.DAY_OF_MONTH);

    nowYear = String.format("%02d", cYear);
    nowMonth = String.format("%02d", cMonth);
    nowDay = String.format("%02d", cDay);

    tvStartTime.setText(nowYear + "-" + nowMonth + "-" + nowDay);
    tvEndTime.setText(nowYear + "-" + nowMonth + "-" + nowDay);
    startYear = nowYear;
    startMonth = nowMonth;
    startDay = nowDay;
}

本周

public void getWeekDate() {
    Calendar calendar = new GregorianCalendar();
    calendar.setFirstDayOfWeek(Calendar.MONDAY);
    calendar.setTime(new Date());
    calendar.set(Calendar.DAY_OF_WEEK, calendar.getFirstDayOfWeek());

    int year = calendar.get(Calendar.YEAR);
    int month = calendar.get(Calendar.MONTH) + 1;
    int day = calendar.get(Calendar.DAY_OF_MONTH);

    Log.i(TAG, String.format("本周：年%d月%d日%d", year, month, day));

    tvStartTime.setText(String.format("%02d", year) + "-" + String.format("%02d", month) + "-" + String.format("%02d", day));
    tvEndTime.setText(nowYear + "-" + nowMonth + "-" + nowDay);

    startYear = String.format("%02d", year);
    startMonth = String.format("%02d", month);
    startDay = String.format("%02d", day);
    endYear = nowYear;
    endMonth = nowMonth;
    endDay = nowDay;
}

本月

public void getMonthDate() {
    Calendar calendar = new GregorianCalendar();

    calendar.add(Calendar.MONTH, 0);
    calendar.set(Calendar.DAY_OF_MONTH, 1);

    int year = calendar.get(Calendar.YEAR);
    int month = calendar.get(Calendar.MONTH) + 1;
    int day = calendar.get(Calendar.DAY_OF_MONTH);

    Log.i(TAG, String.format("本月：年%d月%d日%d", year, month, day));

    tvStartTime.setText(String.format("%02d", year) + "-" + String.format("%02d", month) + "-" + String.format("%02d", day));
    tvEndTime.setText(nowYear + "-" + nowMonth + "-" + nowDay);


    startYear = String.format("%02d", year);
    startMonth = String.format("%02d", month);
    startDay = String.format("%02d", day);
    endYear = nowYear;
    endMonth = nowMonth;
    endDay = nowDay;
}