考虑 java 中的夏令时,如何计算两个日期之间的全天差
How to calculate a full days difference between two dates considering daylight savings in java
我需要在 java 中获取两个日期之间的完整天数(日期以日期类型给出)。
例如:
01/01/2015/12:00:00 - 01/02/2015/11:59:00 不是一整天
我需要考虑夏令时。
我知道 jodatime lib 可以做到这一点,但我达到了 65k 方法限制,我不能使用 jodatime lib。
我尝试了毫秒差异方式和使用 "before" 方法的 while 循环:
Android/Java - Date Difference in days
public class DateDiff {
public static void main(String[] av) {
SimpleDateFormat myFormat = new SimpleDateFormat("MM/dd/yyyy/HH:mm:ss");
String inputString1 = "01/01/2015/12:00:00";
String inputString2 = "01/02/2015/11:59:00";
try {
Date date1 = myFormat.parse(inputString1);
Date date2 = myFormat.parse(inputString2);
long diff = date2.getTime() - date1.getTime(); // Calculate the different
int days = (int) (diff / (1000*60*60*24)); // This convert milliseconds to days
System.out.println ("Days differ: " + days);
} catch (Exception e) {
e.printStackTrace();
}
}
}
下面的代码会计算给定的两个日期,结果打印为:
Days differ: 0
我设法弄明白了:
我使用了一些代码 -
并添加了一些我的:
public static int calcDaysDiff(Date day1, Date day2) {
Date d1 = new Date(day1.getTime());
Date d2 = new Date(day2.getTime());
Calendar date1 = Calendar.getInstance();
date1.setTime(d1);
Calendar date2 = Calendar.getInstance();
date2.setTime(d2);
//checks if the start date is later then the end date - gives 0 if it is
if (date1.get(Calendar.YEAR) >= date2.get(Calendar.YEAR)) {
if (date1.get(Calendar.DAY_OF_YEAR) >= date2.get(Calendar.DAY_OF_YEAR)) {
return 0;
}
}
//checks if there is a daylight saving change between the two dates
int offset = calcOffset(d1, d2);
if (date1.get(Calendar.YEAR) > date2.get(Calendar.YEAR)) {
//swap them
Calendar temp = date1;
date1 = date2;
date2 = temp;
}
return calcDaysDiffAux(date1, date2) + checkFullDay(date1, date2, offset);
}
// check if there is a 24 hour diff between the 2 dates including the daylight saving offset
public static int checkFullDay(Calendar day1, Calendar day2, int offset) {
if (day1.get(Calendar.HOUR_OF_DAY) <= day2.get(Calendar.HOUR_OF_DAY) + offset) {
return 0;
}
return -1;
}
// find the number of days between the 2 dates. check only the dates and not the hours
public static int calcDaysDiffAux(final Calendar day1, final Calendar day2) {
Calendar dayOne = (Calendar) day1.clone(),
dayTwo = (Calendar) day2.clone();
if (dayOne.get(Calendar.YEAR) == dayTwo.get(Calendar.YEAR)) {
return Math.abs(dayOne.get(Calendar.DAY_OF_YEAR) - dayTwo.get(Calendar.DAY_OF_YEAR));
} else {
int extraDays = 0;
while (dayTwo.get(Calendar.YEAR) > dayOne.get(Calendar.YEAR)) {
dayTwo.add(Calendar.YEAR, -1);
// getActualMaximum() important for leap years
extraDays += dayTwo.getActualMaximum(Calendar.DAY_OF_YEAR);
}
return extraDays - day1.get(Calendar.DAY_OF_YEAR) + day2.get(Calendar.DAY_OF_YEAR);
}
}
我需要在 java 中获取两个日期之间的完整天数(日期以日期类型给出)。
例如:
01/01/2015/12:00:00 - 01/02/2015/11:59:00 不是一整天
我需要考虑夏令时。
我知道 jodatime lib 可以做到这一点,但我达到了 65k 方法限制,我不能使用 jodatime lib。
我尝试了毫秒差异方式和使用 "before" 方法的 while 循环:
Android/Java - Date Difference in days
public class DateDiff {
public static void main(String[] av) {
SimpleDateFormat myFormat = new SimpleDateFormat("MM/dd/yyyy/HH:mm:ss");
String inputString1 = "01/01/2015/12:00:00";
String inputString2 = "01/02/2015/11:59:00";
try {
Date date1 = myFormat.parse(inputString1);
Date date2 = myFormat.parse(inputString2);
long diff = date2.getTime() - date1.getTime(); // Calculate the different
int days = (int) (diff / (1000*60*60*24)); // This convert milliseconds to days
System.out.println ("Days differ: " + days);
} catch (Exception e) {
e.printStackTrace();
}
}
}
下面的代码会计算给定的两个日期,结果打印为:
Days differ: 0
我设法弄明白了: 我使用了一些代码 - 并添加了一些我的:
public static int calcDaysDiff(Date day1, Date day2) {
Date d1 = new Date(day1.getTime());
Date d2 = new Date(day2.getTime());
Calendar date1 = Calendar.getInstance();
date1.setTime(d1);
Calendar date2 = Calendar.getInstance();
date2.setTime(d2);
//checks if the start date is later then the end date - gives 0 if it is
if (date1.get(Calendar.YEAR) >= date2.get(Calendar.YEAR)) {
if (date1.get(Calendar.DAY_OF_YEAR) >= date2.get(Calendar.DAY_OF_YEAR)) {
return 0;
}
}
//checks if there is a daylight saving change between the two dates
int offset = calcOffset(d1, d2);
if (date1.get(Calendar.YEAR) > date2.get(Calendar.YEAR)) {
//swap them
Calendar temp = date1;
date1 = date2;
date2 = temp;
}
return calcDaysDiffAux(date1, date2) + checkFullDay(date1, date2, offset);
}
// check if there is a 24 hour diff between the 2 dates including the daylight saving offset
public static int checkFullDay(Calendar day1, Calendar day2, int offset) {
if (day1.get(Calendar.HOUR_OF_DAY) <= day2.get(Calendar.HOUR_OF_DAY) + offset) {
return 0;
}
return -1;
}
// find the number of days between the 2 dates. check only the dates and not the hours
public static int calcDaysDiffAux(final Calendar day1, final Calendar day2) {
Calendar dayOne = (Calendar) day1.clone(),
dayTwo = (Calendar) day2.clone();
if (dayOne.get(Calendar.YEAR) == dayTwo.get(Calendar.YEAR)) {
return Math.abs(dayOne.get(Calendar.DAY_OF_YEAR) - dayTwo.get(Calendar.DAY_OF_YEAR));
} else {
int extraDays = 0;
while (dayTwo.get(Calendar.YEAR) > dayOne.get(Calendar.YEAR)) {
dayTwo.add(Calendar.YEAR, -1);
// getActualMaximum() important for leap years
extraDays += dayTwo.getActualMaximum(Calendar.DAY_OF_YEAR);
}
return extraDays - day1.get(Calendar.DAY_OF_YEAR) + day2.get(Calendar.DAY_OF_YEAR);
}
}