How can I compare Date class with System.currentTimeMillis() in java

Question

How can I compare if a object Date like "2013-12-09 00:00:00" is greater than actual time (System.currentTimeMillis()) in java?

if (object.getDate().getSeconds() > System.currentTimeMillis())
  //do something

Answer 1

您可以使用if (object.getDate().after(Calendar.getInstance().getTime()) {

Answer 2

在Date对象中调用getTime()而不是getSeconds() 。

Answer 3

getSeconds doesn't return the amount of seconds since epoch. It returns the seconds in minute of the Date instance.

So I guess that what you need is:

if (object.getDate().getTime() > System.currentTimeMillis())

Answer 4

You should depend on a good date-time library rather than doing your own math with System milliseconds.

In Java now (year 2013), that means Joda-Time 2.3. In Java 8, consider moving to the new java.time.* classes from JSR 310. Those classes are inspired by Joda-Time but are entirely re-architected.

Joda-Time offers the methods isBefore and isAfter , just what you need for you comparison.

Your question fails to address time zones. So for my example code below I assumed your given date-time was in UTC /GMT. If that is not the case, then tweak the code by changing the call to withZoneUTC() to another withZone method.

// © 2013 Basil Bourque. This source code may be used freely forever by anyone taking full responsibility for doing so.
// import org.joda.time.*;
// import org.joda.time.format.*;

DateTimeFormatter formatter = org.joda.time.format.DateTimeFormat.forPattern( "yyyy-MM-dd' 'HH:mm:ss" );

DateTime dateTimeInUTC = formatter.withZoneUTC().parseDateTime( "2013-12-09 00:00:00" );
DateTime now = new DateTime();
Boolean isFuture = ( dateTimeInUTC.isAfter( now ) );

System.out.println( "dateTimeInUTC: " + dateTimeInUTC );
System.out.println( "now: " + now );
System.out.println( "now in UTC: " + now.toDateTime( DateTimeZone.UTC ) );
System.out.println( "isFuture: " + isFuture );

When run…

dateTimeInUTC: 2013-12-09T00:00:00.000Z
now: 2013-12-09T23:46:05.902-08:00
now in UTC: 2013-12-10T07:46:05.902Z
isFuture: false