common_helper/src/main/java/com/xiongyingqi/util/DateHelper.java
public static long getDays(String date1, String date2) {
        if (date1 == null || date1.equals(""))
            return 0;
        if (date2 == null || date2.equals(""))
            return 0;
        // 转换为标准时间
        SimpleDateFormat myFormatter = new SimpleDateFormat("yyyy-MM-dd");
        Date date = null;
        Date mydate = null;
        try {
            date = myFormatter.parse(date1);
            mydate = myFormatter.parse(date2);
        } catch (Exception e) {
        }
        long day = (date.getTime() - mydate.getTime()) / (24 * 60 * 60 * 1000);
        return day;
    }
public static long getDays(String date1, String date2) {
        if (date1 == null || date1.equals(""))
            return 0;
        if (date2 == null || date2.equals(""))
            return 0;
        // 转换为标准时间
        SimpleDateFormat myFormatter = new SimpleDateFormat("yyyy-MM-dd");
        Date date = null;
        Date mydate = null;
        try {
            date = myFormatter.parse(date1);
            mydate = myFormatter.parse(date2);
        } catch (Exception e) {
        }
        long day = (date.getTime() - mydate.getTime()) / (24 * 60 * 60 * 1000);
        return day;
    }
两个时间之间的天数

@param date1
@param date2
@return