<%@page import="java.util.*"%>
<%@page import="java.text.*"%>
<%
        try {
    String date1 = "25/04/2012";
    String time1 = "11:00 AM";
    String date2 = "26/04/2012";
    String time2 = "12:15 AM";

    String format = "dd/MM/yyyy hh:mm a";

    SimpleDateFormat sdf = new SimpleDateFormat(format);

    Date dateObj1 = sdf.parse(date1 + " " + time1);
    Date dateObj2 = sdf.parse(date2 + " " + time2);


    long diff = dateObj2.getTime() - dateObj1.getTime();
    double diffInHours = diff / ((double) 1000 * 60 * 60);
    out.println(diffInHours+"<br>");
    out.println("Hours " + (int)diffInHours+"<br>");
    out.println("Minutes " + (diffInHours - (int)diffInHours)*60 );

} catch (ParseException e) {
    e.printStackTrace();
}
    }
}

The above code parse two times and ouputs the difference between two times in terms of hours.