关于日历

mCalendar = Calendar.getInstance();
/**
 * 日历
 */
//时间显示
String dataSplit = getTimeStyle(mCalendar);
String[] dataSplits = dataSplit.split("-");
mTvTimeEnd.setText(dataSplits[0] + "-" + String.valueOf(getStringDate(Integer.valueOf(dataSplits[1]))) + "-" + String.valueOf(getStringDate(Integer.valueOf(dataSplits[2]))));
//时间间隔
mCalendar.add(Calendar.DAY_OF_MONTH, -30);
String dataSplit1 = getTimeStyle(mCalendar);
String[] dataSplit1s = dataSplit1.split("-");
mTvTimeStart.setText(dataSplit1s[0] + "-" + String.valueOf(getStringDate(Integer.valueOf(dataSplit1s[1]))) + "-" + String.valueOf(getStringDate(Integer.valueOf(dataSplit1s[2]))));

private Calendar showDatePickers(Calendar calendar) {
    DatePickerDialog dialog = new DatePickerDialog(mContext, (view, year, month, dayOfMonth) -> {
        calendar.set(year, month, dayOfMonth);
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
    }, calendar.get(Calendar.YEAR),
            calendar.get(Calendar.MONTH),
            calendar.get(Calendar.DAY_OF_MONTH));
    //设置日期最小值(只能选择当前时间以后的时间)
    dialog.getDatePicker().setMinDate(Calendar.getInstance().getTimeInMillis());
    dialog.show();
    return calendar;
}

@Override
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if (data != null && resultCode == PeriodTimeDateActivity.RESULT_OK) {
        ArrayList<Integer> date = data.getIntegerArrayListExtra(PeriodTimeDateActivity.DEFAULT_DATE);
        mTvTimeStart.setText(date.get(0) + "-" + getStringDate(date.get(1)) + "-" + getStringDate(date.get(2)));
        mTvTimeEnd.setText(date.get(3) + "-" + getStringDate(date.get(4)) + "-" + getStringDate(date.get(5)));
    }
}

/**
 * 日期格式转换
 */
private String getTimeStyle(Calendar calendar) {
    String f = "%d-%d-%d";

    int year = calendar.get(Calendar.YEAR);
    int month = calendar.get(Calendar.MONTH);
    int day = calendar.get(Calendar.DAY_OF_MONTH);
    return String.format(f, year, month + 1, day);
}

private String getStringDate(int num) {
    if (num < 10) {
        return "0" + num;
    }
    return String.valueOf(num);
}