Table of contents
2. Implementation of specific methods
2.1 Get the start time of the day
2.2 Get the end time of the day
2.3 Get yesterday's start time
2.7 Get the start time of this week
2.8 Get the end time of this week
2.9 Get the start time of this month
2.10 Get the end time of this month
2.11 Get the start time of the previous month
2.12 Get the end time of the previous month
2.13 Get the start time of this year
2.14 Get the start time of n years ago
2.15 Get the end time of n years ago
2.16 Get the end time of the current year
2.17 Get the start time of a certain date
2.18 Get the end time of a certain date
2.19 Get which year this year is
2.20 Get which month this month is
2.21 Time difference calculation verification (start and end time cannot be empty)
2.22 The number of days obtained by subtracting dates (less than one day is 1 and overtime is -1)
2.23 The number of days obtained by subtracting two dates [inaccurate]
2.24 The hour obtained by subtracting two dates
2.25 The number of milliseconds obtained by subtracting two dates
2.26 Get the largest date of two dates
2.27 Get the smallest date of two dates
2.28 Return the first month of the quarter of a certain month
2.29 Return the date of the next few days of a date
2.30 returns the date of a few days before a date
2.33 Get the first day of a certain year and month
2.34 Get the date of the last day of a certain month in a certain year
2.35 year, month, day into -> year, month, day, hour, minute, second
2.36 Custom conversion of year, month, day -> year, month, day, hour, minute, second
2.37 The number of days that date2 is more than date1
2.38 Seconds (s) Hours, minutes, seconds or hours, minutes, seconds
2.39 Milliseconds (ms) elapsed time, minutes, seconds or hours, minutes, seconds
2.40 Get the current time [accurate]
2.41 Time string conversion date
2.42 Get the date type time after? days
1 Introduction:
In normal development, there will always be some time to calculate, and writing it every time is not only redundant but also a waste of time
Here it encapsulates the most common way of writing in n
Continuous update Now it has been updated to 43 , which global search can be used to copy
(ps: It’s best to look at the catalog or it’s not easy to find)
2. Implementation of specific methods
2.1 Get the start time of the day
public static Date getDayBegin() {
Calendar cal = new GregorianCalendar();
cal.set(Calendar.HOUR_OF_DAY, 0);
cal.set(Calendar.MINUTE, 0);
cal.set(Calendar.SECOND, 0);
cal.set(Calendar.MILLISECOND, 0);
return cal.getTime();
}2.2 Get the end time of the day
public static Date getDayEnd() {
Calendar cal = new GregorianCalendar();
cal.set(Calendar.HOUR_OF_DAY, 23);
cal.set(Calendar.MINUTE, 59);
cal.set(Calendar.SECOND, 59);
return cal.getTime();
}2.3 Get yesterday's start time
public static Date getBeginDayOfYesterday() {
Calendar cal = new GregorianCalendar();
cal.setTime(getDayBegin());
cal.add(Calendar.DAY_OF_MONTH, -1);
return cal.getTime();
}2.4 Get yesterday's end time
public static Date getEndDayOfYesterDay() {
Calendar cal = new GregorianCalendar();
cal.setTime(getDayEnd());
cal.add(Calendar.DAY_OF_MONTH, -1);
return cal.getTime();
}2.5 Get tomorrow's start time
public static Date getBeginDayOfTomorrow() {
Calendar cal = new GregorianCalendar();
cal.setTime(getDayBegin());
cal.add(Calendar.DAY_OF_MONTH, 1);
return cal.getTime();
}2.6 Get tomorrow's end time
public static Date getEndDayOfTomorrow() {
Calendar cal = new GregorianCalendar();
cal.setTime(getDayEnd());
cal.add(Calendar.DAY_OF_MONTH, 1);
return cal.getTime();
}2.7 Get the start time of this week
public static Date getBeginDayOfWeek() {
Date date = new Date();
if (date == null) {
return null;
}
Calendar cal = Calendar.getInstance();
cal.setTime(date);
int dayofweek = cal.get(Calendar.DAY_OF_WEEK);
if (dayofweek == 1) {
dayofweek += 7;
}
cal.add(Calendar.DATE, 2 - dayofweek);
return getDayStartTime(cal.getTime());
}2.8 Get the end time of this week
public static Date getEndDayOfWeek() {
Calendar cal = Calendar.getInstance();
cal.setTime(getBeginDayOfWeek());
cal.add(Calendar.DAY_OF_WEEK, 6);
Date weekEndSta = cal.getTime();
return getDayEndTime(weekEndSta);
}2.9 Get the start time of this month
public static Date getBeginDayOfMonth() {
Calendar calendar = Calendar.getInstance();
calendar.set(getNowYear(), getNowMonth() - 1, 1);
return getDayStartTime(calendar.getTime());
}2.10 Get the end time of this month
public static Date getEndDayOfMonth() {
Calendar calendar = Calendar.getInstance();
calendar.set(getNowYear(), getNowMonth() - 1, 1);
int day = calendar.getActualMaximum(5);
calendar.set(getNowYear(), getNowMonth() - 1, day);
return getDayEndTime(calendar.getTime());
}2.11 Get the start time of the previous month
public static Date getBeginDayOfLastMonth(int n) {
Date date = new Date();
Calendar calendar = Calendar.getInstance();
calendar.setTime(date);
calendar.add(calendar.MONTH, -n);
calendar.set(calendar.DAY_OF_MONTH, 1);
return getDayStartTime(calendar.getTime());
}2.12 Get the end time of the previous month
public static Date getEndDayOfLastMonth(int n) {
Date date = new Date();
Calendar calendar = Calendar.getInstance();
calendar.setTime(date);
calendar.add(calendar.MONTH, -n);
int day = calendar.getActualMaximum(5);
calendar.set(calendar.DAY_OF_MONTH, day);
return getDayEndTime(calendar.getTime());
}2.13 Get the start time of this year
public static Date getBeginDayOfYear() {
Calendar cal = Calendar.getInstance();
cal.set(Calendar.YEAR, getNowYear());
cal.set(Calendar.MONTH, Calendar.JANUARY);
cal.set(Calendar.DATE, 1);
return getDayStartTime(cal.getTime());
}2.14 Get the start time of n years ago
public static Date getBeginDayOfLastYear(int n) {
Calendar cal = Calendar.getInstance();
cal.set(Calendar.YEAR, getNowYear() - n);
cal.set(Calendar.MONTH, Calendar.JANUARY);
cal.set(Calendar.DATE, 1);
return getDayStartTime(cal.getTime());
}
2.15 Get the end time of n years ago
public static Date getEndDayOfLastYear(int n) {
Calendar cal = Calendar.getInstance();
cal.set(Calendar.YEAR, getNowYear() - n);
cal.set(Calendar.MONTH, Calendar.DECEMBER);
cal.set(Calendar.DATE, 31);
return getDayEndTime(cal.getTime());
}2.16 Get the end time of the current year
public static Date getEndDayOfYear() {
Calendar cal = Calendar.getInstance();
cal.set(Calendar.YEAR, getNowYear());
cal.set(Calendar.MONTH, Calendar.DECEMBER);
cal.set(Calendar.DATE, 31);
return getDayEndTime(cal.getTime());
}2.17 Get the start time of a certain date
public static Timestamp getDayStartTime(Date d) {
Calendar calendar = Calendar.getInstance();
if (null != d)
calendar.setTime(d);
calendar.set(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH), calendar.get(Calendar.DAY_OF_MONTH), 0,
0, 0);
calendar.set(Calendar.MILLISECOND, 0);
return new Timestamp(calendar.getTimeInMillis());
}2.18 Get the end time of a certain date
public static Timestamp getDayEndTime(Date d) {
Calendar calendar = Calendar.getInstance();
if (null != d)
calendar.setTime(d);
calendar.set(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH), calendar.get(Calendar.DAY_OF_MONTH), 23,
59, 59);
calendar.set(Calendar.MILLISECOND, 999);
return new Timestamp(calendar.getTimeInMillis());
}2.19 Get which year this year is
// 获取今年是哪一年
public static Integer getNowYear() {
Date date = new Date();
GregorianCalendar gc = (GregorianCalendar) Calendar.getInstance();
gc.setTime(date);
return gc.get(Calendar.YEAR);
}2.20 Get which month this month is
public static int getNowMonth() {
Date date = new Date();
GregorianCalendar gc = (GregorianCalendar) Calendar.getInstance();
gc.setTime(date);
return gc.get(Calendar.MONTH) + 1;
}2.21 Time difference calculation verification (start and end time cannot be empty)
public static void dateMarginCheck(Date beginDate, Date endDate) {
if (beginDate == null || endDate == null) {
throw new IllegalArgumentException("getDiffDays param is null!");
}
}
2.22 The number of days obtained by subtracting dates (less than one day is 1 and overtime is -1)
public static int getExactDiffDays(Date beginDate, Date endDate) {
dateMarginCheck(beginDate, endDate);
BigDecimal subtract = new BigDecimal(endDate.getTime()).subtract(new BigDecimal(beginDate.getTime()));
BigDecimal divide = subtract.divide(new BigDecimal(1000 * 60 * 60 * 24), RoundingMode.UP);
return divide.intValue();
}2.23 The number of days obtained by subtracting two dates [inaccurate]
// 两个日期相减得到的天数
public static int getDiffDays(Date beginDate, Date endDate) {
dateMarginCheck(beginDate, endDate);
long diff = (endDate.getTime() - beginDate.getTime() - 1000) / (1000 * 60 * 60 * 24);
return new Long(diff).intValue();
}2.24 The hour obtained by subtracting two dates
public static int getDiffHours(Date beginDate, Date endDate) {
dateMarginCheck(beginDate, endDate);
long diff = (endDate.getTime() - beginDate.getTime()) / (1000 * 60 * 60);
return new Long(diff).intValue();
}
2.25 The number of milliseconds obtained by subtracting two dates
public static long dateDiff(Date beginDate, Date endDate) {
//开始时间或结束时间为空 返回0L 毫秒
if (beginDate == null || endDate == null) {
return 0L;
}
long date1ms = beginDate.getTime();
long date2ms = endDate.getTime();
return date2ms - date1ms;
}2.26 Get the largest date of two dates
public static Date max(Date beginDate, Date endDate) {
if (beginDate == null) {
return endDate;
}
if (endDate == null) {
return beginDate;
}
if (beginDate.after(endDate)) {
return beginDate;
}
return endDate;
}2.27 Get the smallest date of two dates
public static Date min(Date beginDate, Date endDate) {
if (beginDate == null) {
return endDate;
}
if (endDate == null) {
return beginDate;
}
if (beginDate.after(endDate)) {
return endDate;
}
return beginDate;
}2.28 Return the first month of the quarter of a certain month
public static Date getFirstSeasonDate(Date date) {
final int[] SEASON = {1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4};
Calendar cal = Calendar.getInstance();
cal.setTime(date);
int sean = SEASON[cal.get(Calendar.MONTH)];
cal.set(Calendar.MONTH, sean * 3 - 3);
return cal.getTime();
}2.29 Return the date of the next few days of a date
public static Date getNextDay(Date date, int i) {
Calendar cal = new GregorianCalendar();
cal.setTime(date);
cal.set(Calendar.DATE, cal.get(Calendar.DATE) + i);
return cal.getTime();
}
2.30 returns the date of a few days before a date
public static Date getFrontDay(Date date, int i) {
Calendar cal = new GregorianCalendar();
cal.setTime(date);
cal.set(Calendar.DATE, cal.get(Calendar.DATE) - i);
return cal.getTime();
}2.31 Obtain the collection of sliced dates from a certain month to a certain year and a certain month by day
public static List getTimeList(int beginYear, int beginMonth, int endYear, int endMonth, int k) {
List list = new ArrayList();
if (beginYear == endYear) {
for (int j = beginMonth; j <= endMonth; j++) {
list.add(getTimeList(beginYear, j, k));
}
} else {
{
for (int j = beginMonth; j < 12; j++) {
list.add(getTimeList(beginYear, j, k));
}
for (int i = beginYear + 1; i < endYear; i++) {
for (int j = 0; j < 12; j++) {
list.add(getTimeList(i, j, k));
}
}
for (int j = 0; j <= endMonth; j++) {
list.add(getTimeList(endYear, j, k));
}
}
}
return list;
}2.32 Obtain a date set sliced by day in a certain year and month (a set of dates separated by days in a certain month)
public static List getTimeList(int beginYear, int beginMonth, int k) {
List list = new ArrayList();
Calendar begincal = new GregorianCalendar(beginYear, beginMonth, 1);
int max = begincal.getActualMaximum(Calendar.DATE);
for (int i = 1; i < max; i = i + k) {
list.add(begincal.getTime());
begincal.add(Calendar.DATE, k);
}
begincal = new GregorianCalendar(beginYear, beginMonth, max);
list.add(begincal.getTime());
return list;
}2.33 Get the first day of a certain year and month
public static Date getStartMonthDate(int year, int month) {
Calendar calendar = Calendar.getInstance();
calendar.set(year, month - 1, 1, 0, 0, 0);
return calendar.getTime();
}2.34 Get the date of the last day of a certain month in a certain year
public static Date getEndMonthDate(int year, int month) {
Calendar calendar = Calendar.getInstance();
calendar.set(year, month - 1, 1);
int day = calendar.getActualMaximum(5);
calendar.set(year, month - 1, day, 23, 59, 59);
return calendar.getTime();
}2.35 year, month, day into -> year, month, day, hour, minute, second
change( 2023-06-23 ) to ( 2023-06-23 23:59:59 )
public static Date getDateDetail(Date date) {
Calendar calendar = Calendar.getInstance();
calendar.setTime(date);
calendar.add(Calendar.HOUR, 23);//时
calendar.add(Calendar.MINUTE, 59);//时
calendar.add(Calendar.SECOND, 59);//秒
return calendar.getTime();
}2.36 Custom conversion of year, month, day -> year, month, day, hour, minute, second
change( 2023-06-23 ) to ( 2023-06-23 ?:?:? )
public static Date getDateDetail(Date date, Integer hour, Integer minute, Integer second) {
Calendar calendar = Calendar.getInstance();
calendar.setTime(date);
calendar.add(Calendar.HOUR, hour);//时
calendar.add(Calendar.MINUTE, minute);//时
calendar.add(Calendar.SECOND, second);//秒
return calendar.getTime();
}2.37 The number of days that date2 is more than date1
public static int differentDays(Date date1, Date date2) {
Calendar cal1 = Calendar.getInstance();
cal1.setTime(date1);
Calendar cal2 = Calendar.getInstance();
cal2.setTime(date2);
int day1 = cal1.get(Calendar.DAY_OF_YEAR);
int day2 = cal2.get(Calendar.DAY_OF_YEAR);
int year1 = cal1.get(Calendar.YEAR);
int year2 = cal2.get(Calendar.YEAR);
if (year1 != year2) //同一年
{
int timeDistance = 0;
for (int i = year1; i < year2; i++) {
if (i % 4 == 0 && i % 100 != 0 || i % 400 == 0) //闰年
{
timeDistance += 366;
} else //不是闰年
{
timeDistance += 365;
}
}
return timeDistance + (day2 - day1);
} else { //不同年
return day2 - day1;
}
}2.38 Seconds (s) Hours, minutes, seconds or hours, minutes, seconds
public static String toDayHoursMinSec(Long time) {
long day = TimeUnit.SECONDS.toDays(time);
long hours = TimeUnit.SECONDS.toHours(time) - TimeUnit.DAYS.toHours(TimeUnit.SECONDS.toDays(time));
long minutes = TimeUnit.SECONDS.toMinutes(time) - TimeUnit.HOURS.toMinutes(TimeUnit.SECONDS.toHours(time));
long seconds = TimeUnit.SECONDS.toSeconds(time) - TimeUnit.MINUTES.toSeconds(TimeUnit.SECONDS.toMinutes(time));
if (day > 0) {
return String.format("%s天%s时%s分%s秒", day, hours, minutes, seconds);
}
return String.format("%s时%s分%s秒", hours, minutes, seconds);
}2.39 Milliseconds (ms) elapsed time, minutes, seconds or hours, minutes, seconds
public static String toDayHoursMinMilliSec(Long time) {
long day = TimeUnit.MILLISECONDS.toDays(time);
long hours = TimeUnit.MILLISECONDS.toHours(time) - TimeUnit.DAYS.toHours(TimeUnit.MILLISECONDS.toDays(time));
long minutes = TimeUnit.MILLISECONDS.toMinutes(time) - TimeUnit.HOURS.toMinutes(TimeUnit.MILLISECONDS.toHours(time));
long seconds = TimeUnit.MILLISECONDS.toSeconds(time) - TimeUnit.MINUTES.toSeconds(TimeUnit.MILLISECONDS.toMinutes(time));
if (day > 0) {
return String.format("%s天%s时%s分%s秒", day, hours, minutes, seconds);
}
return String.format("%s时%s分%s秒", hours, minutes, seconds);
}2.40 Get the current time [accurate]
and new Date (there is a difference)
public static Date getNowDate() {
Calendar calendar = Calendar.getInstance();
calendar.set(Calendar.MILLISECOND, 0);
return calendar.getTime();
}2.41 Time string conversion date
public static Date getStrToDate(String dateStr) throws ParseException {
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
return format.parse(dateStr);
}2.42 Get the date type time after? days
public static Date getAfterDayEnd(Date startTime, int days) {
Calendar cal = Calendar.getInstance();
cal.setTime(startTime);
cal.add(Calendar.DAY_OF_MONTH, days);//跟随月份走的天数<构造器中写了每个月的天数...>
return cal.getTime();
}2.43 n hours later time
public static Date getAfterHourEnd(Date startTime, int hours) {
Calendar cal = Calendar.getInstance();
cal.setTime(startTime);
cal.add(Calendar.HOUR_OF_DAY, hours);//24小时制度
return cal.getTime();
}