Two java.sql.Date Not Equal By compareTo() Function

[sudipto shekhar]

Hello,

I have the following code:

 long time = System.currentTimeMillis();
		java.sql.Date date = new java.sql.Date(time);
		System.out.println(date); --------------------------------------------> Line 1
		
		
		long time2 = System.currentTimeMillis();
		java.sql.Date date2 = new java.sql.Date(time2);
		
		System.out.println(date2); -------------------------------------------> Line 2
		
		System.out.println(date.compareTo(date2));  ----------------------> Line 3

The output of Line 1 and Line 2 is :

2016-07-07
2016-07-07

The expected output of Line 3 is '0' but the output of the code is '-1'. I am not able to figure out the reason.

Please help!

[Bear Bibeault]

Because the time within the dates are likely different.

[Liutauras Vilda]

Hi.

long time = System.currentTimeMillis();

Returns the current time in milliseconds. That time is captured when line1 gets executed.

 long time2 = System.currentTimeMillis();

Returns the current time in milliseconds. That time is captured when line6 gets executed.

When you trying to print sql.Date object it invokes toString() method overridden by that class which says "Formats a date in the date escape format yyyy-mm-dd."
So, since two different code lines manage to run on the same day and only milliseconds differ, you see same date, while behind the hood it isn't.

[Campbell Ritchie]

Useful way to time a print call. The time it takes to contact the command line/terminal via the Operating System is obviously long enough to make a difference.
Avoid classes like Date and Calendar as much as possible. Use the new Java8 date/time classes whenever you can. You probably only need java.sql.Date when you are dealing directly with databases.

[sudipto shekhar]

Yes, I figured this out eventually.

What I am trying to achieve here is compare a java.sql.Date to the current system date; if the sql date is before the current system date the check shall return TRUE. But this check becomes TRUE even if the date is equal to current system date (this check should return false).

Any effective way to achieve this?

Kindly suggest.

[Campbell Ritchie]

Are you using < 0 or <= 0 in your comparisons? You should show us your code, so we know what is going on.
Let's try getting rid of the legacy code.

Date d = ...;
Instant inst = d.toInstant();

An Instant object encapsulates the time elapsed since 1st January 1970, just as a Date object does, but it multiplies the milliseconds by 1000000 to make nanoseconds. Now let's see if we can't get a current time Instant object. Easy: use its now() method and Bob's your uncle:-

Instant now = Instant.now();
System.out.printf("inst.isBefore(now): %b%ninst.isAfter(now): %b%ninst.equals(now): %b%n",
              inst.isBefore(now), inst.isAfter(now), inst.equals(now));

[sudipto shekhar]

Apologies as I forgot to mention that I am on Java6.

I am using date.before(anotherDate) method to compare two dates.

Moreover, Instant is a class that I could not find. Please let me know what am I missing.

[Campbell Ritchie]

Why are you still on Java6? That has been obsolete for a couple of years. I said in a link yesterday,

the new Java8 date/time classes