Question

I want to calculate the difference between two date/time in java using Date and Calendar classes. The format that I have is “2012-01-24 12:30:00 PM”.

I have implemented my own method and also google it to work with others, but haven’t getting the right hint to handle AM and PM values.

The date/time difference got troubled whenever the time have 12(AM/PM) in it. For example if I have date/time “2012-01-24 12:30:00 PM” and “2012-01-24 02:30:00 PM” it shows the difference is 10 hours.

Considering the code on this link how can it be modified to handle AM and PM.

To convert String date into Date I use following code:

    String sessionTimeStart = "2012-01-24 12:30:00 PM";
    String sessionTimerEndOrCurrent = "2012-01-24 02:30:00 PM";
    SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss a"); 

    Date d1 = null;
    Date d0 = null; 
    try {
        d1 = format.parse(sessionTimeStart);
        d0 = format.parse(sessionTimerEndOrCurrent);
    } catch (ParseException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    }

Answer 1

The problem is your date format: instead of yyyy-MM-dd HH:mm:ss a use yyyy-MM-dd hh:mm:ss a.

HH will be the hour in day (0-23) whereas hh will be the hour in AM/PM (1-12). Thus with your date format 02:30:00 will be parsed as just that instead of being converted to the PM version (which in hour of day would be 14:30:00).