如何计算三个时间之间的差异？

Question

Works with two different times but not showing correct calculation with three different times.

SimpleDateFormat format = new SimpleDateFormat("hh:mm");
Date date1 = format.parse(timestart);
Date date2 = format.parse(timeend);
Date date3 = format.parse(breaktime);
long mills = date2.getTime() - date1.getTime() - date3.getTime();
int hours = (int)(mills/(1000 * 60 * 60));
int mins = (int) mills/(1000*60) %60;

Answer 1

Are you trying to calculate:

Work_Duration = End_Time - Start_Time - Break_Duration?

If yes, you can simply use an integer/long variable to represent break duration in units of your choice (seconds or minutes). It need not be a Date object.

You can calculate:

Break_Duration = Break_End_Time - Break_Start_Time

So, you will have 2 Date objects (one for start of break, another for the end of break time), instead of just one for breaktime.

Answer 2

If you want calculate the different between timeend end timestart and the different between timeend end breaktime time you need do:

SimpleDateFormat format = new SimpleDateFormat("hh:mm");
Date date1 = format.parse(timestart);
Date date2 = format.parse(timeend);
Date date3 = format.parse(breaktime);
long mills = date2.getTime() - date1.getTime();
long mills2 = date2.getTime() - date3.getTime();
int hours = (int)(mills/(1000 * 60 * 60));
int mins = (int) mills/(1000*60);
int hours2 = (int)(mills/(1000 * 60 * 60));
int mins2 = (int) mills/(1000*60);

Because if you do date1- date2- date3 you have a negative number (es 1535983083-1535810283-1535896683)

Answer 3

The key problem here is that date3 , the duration of the break time, is using an unsuitable object. date1 and date2 are correctly defined as Date objects as they represent times of the day (10:00 and 05:00, as you mention in your comment ). However, by setting date3 to be 00:30, you're declaring it to being a time of day equivalent to half past midnight today , instead you want this to be a time period of 30 minutes.

So you'll want to take the difference between date1 and date2 , and then subtract the number of minutes taken from the break like this (assuming breakLength is 30 minutes for example):

SimpleDateFormat format = new SimpleDateFormat("hh:mm");
Date date1 = format.parse(timestart);
Date date2 = format.parse(timeend);
long breakLengthMillis = TimeUnit.MINUTES.toMillis(breakLength)

long mills = date2.getTime() - date1.getTime() - breakLengthMillis;
int hours = (int)(mills/(1000 * 60 * 60));
int mins = (int) mills/(1000*60) % 60;

Alternatively, if you want to measure a break by its start and end times, you could use this:

SimpleDateFormat format = new SimpleDateFormat("hh:mm");
Date date1 = format.parse(timestart);
Date date2 = format.parse(timeend);
Date date3 = format.parse(breakStart);       // Start time of break
Date date4 = format.parse(breakEnd);         // End time of break

long mills = date2.getTime() - date1.getTime() - (date4.getTime() - date3.getTime());
int hours = (int)(mills/(1000 * 60 * 60));
int mins = (int) mills/(1000*60) % 60;