Doubt in Data

[Lukasz Szwed]

Hi,

I'm brand new in Javarunch.
I've just started to learn for SCJP. I've already found answers for most of my questions here.

Can someone explain me why this code below produce the:
Thu Jan 01 01:00:00 GMT 1970
I thought that the result will be:
Thu Jan 01 00:00:00 GMT 1970

public class Test {
 
    public static void main(String[] args) {
 
        Date d1 = new Date();
        d1.setTime(0l);
        System.out.println(d1);
    }
}

[Collins Mbianda]

Hi Lukasz !!!

Take a look to the javadoc of the Date class.

public void setTime(long time)
 
    Sets this Date object to represent a point in time that is time milliseconds after January 1, 1970 00:00:00 GMT.
 
    Parameters:
        time - the number of milliseconds.
 

Hope it help.

[Lukasz Szwed]

Hi,

I did look into documentation before I posted here.

But I don't understand why if I pass 0l (0 long) paramenter, the date is set as a Thu Jan 01 01:00:00 GMT 1970 shouldn't be set as a 00:00:00 ?

As you mentioned, the parameter means: Sets this Date object to represent a point in time that is time milliseconds after January 1, 1970 00:00:00 GMT.

So I'm still confiused, If I pass 0 milliseconds (and from January 1, 1970 00:00:00 GMT past 0 miliseconds) the time should be the same, so why it is 1 hour later?

Please tell me where I am wrong?

[Collins Mbianda]

If i run your code, i will have: Thu Jan 01 01:00:00 CET 1970

This because my Time Zone is CET and CET is 1 hour ahead of GMC.

Are you sure that your Time Zone is GMC ?

Try to format your answer in GMC and see the answer. Use this code;

public class MyClass {
 
    /**
     * @param args
     * @throws ParseException
     */
    public static void main(String[] args) throws ParseException {
 
Date d1 = new Date();
d1.setTime(0l);
System.out.println(d1);
 
DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
dateFormat.setTimeZone(TimeZone.getTimeZone("GMC"));
 
// Formats the date in the GMC timezone
System.out.println(dateFormat.format(d1));
 
    }
}

[Lukasz Szwed]

Thank you...

That's clear enough.