Convert date time to file date time

[sam patel]

Hi,
I have standard delphi function which conver datetime to filedatetime here is the description
function DateTimeToFileDate(DateTime: TDateTime): Integer;
Description
Use DateTimeToFileDate to convert a TDateTime value, which is the representation of date-and-time values used by the VCL, to a DOS date-and-time value.
For example, use DateTimeToFileDate to convert a TDateTime value to a
format that can be used as the Age parameter of FileSetDate. You may
also need to use DateTimeToFileDate to convert a TDateTime so that it
is compatible with the Time field of the TSearchRec record used by the FindFirst
and FindNext functions.
Lo returns the low-order Byte of the argument X as an unsigned value. X is an expression of type Integer.
Use Hi to obtain the high-order byte of an expression of type Word or Integer.
Note: Hi treats Integer as a 16-bit value, even if it is 32-bit.
This is the delphi code that convert the date
year=2003
month=5
day=28
sec=57
min=45
hr=13
msec=107

LongRec(Result).Lo := (Sec shr 1) or (Min shl 5) or (Hour shl 11);
LongRec(Result).Hi := Day or (Month shl 5) or ((Year - 1980) shl 9);

output Result is --> 784100796
Any help will be highly appreciated.
Thanks.

[Carl Trusiak]

Sounds like you have a good handle on the requirements. If you look what is going on, you break the date into it's field elements. A good canidate for this portion would be Calendar. Then these values are shifted by the amounts lists, the results ored together and the High shifted and ored to the low.
I took a quick stab at this and here is the code I came up with:

import java.util.Calendar;
import java.util.GregorianCalendar;
public class DosFileDate {
    
    /** Creates a new instance of DosFileDate */
    public DosFileDate() {
    }
    
    public static int getDosFileDate(java.util.Date date){
        Calendar cal = new GregorianCalendar();
        cal.setTime(date);
        int year = cal.get(Calendar.YEAR);
        int month = cal.get(Calendar.MONTH) + 1;
        int day = cal.get(Calendar.DAY_OF_MONTH);
        int hour = cal.get(Calendar.HOUR_OF_DAY);
        int min = cal.get(Calendar.MINUTE);
        int sec = cal.get(Calendar.SECOND);
        
        int lo = ((sec >> 1) | (min << 5) | (hour << 11));
        int hi = (day | ( month << 5) | ((year - 1980) << 9));
        int dTime = (hi << 16) | lo;
        return dTime;
    }
    
    public static void main(String args[]){
        Calendar cal = new GregorianCalendar();
        cal.set(2003, 4, 28, 13, 45, 57);
        System.out.println(cal.getTime());
        System.out.println("Dos File Date Time is : " + getDosFileDate(cal.getTime()));
    }
}

To better understand bit operations in Java, Read Cat and Mouse Game with Bits