Convert Epoch seconds to date and time format in Java

Question

I have seconds since 1970 january 1 UTC (Epoch time).

1320105600

I need to convert that seconds into date and time in below format.

Friday,November 4,2011 5:00,AM

How can I achieve this?

Answer 1

In case you're restricted to legacy java.util.Date and java.util.Calendar APIs, you need to take into account that the timestamps are interpreted in milliseconds, not seconds. So you first need to multiply it by 1000 to get the timestamp in milliseconds.

long seconds = 1320105600;
long millis = seconds * 1000;

This way you can feed it to a.o. the constructor of java.util.Date and finally use SimpleDateFormat to convert a java.util.Date to java.lang.String in the desired date format pattern, if necessary with a predefined time zone (otherwise it would use the system default time zone, which is not GMT/UTC per se and thus the formatted time might be off).

Date date = new Date(millis);
SimpleDateFormat sdf = new SimpleDateFormat("EEEE,MMMM d,yyyy h:mm,a", Locale.ENGLISH);
sdf.setTimeZone(TimeZone.getTimeZone("UTC"));
String formattedDate = sdf.format(date);
System.out.println(formattedDate); // Tuesday,November 1,2011 12:00,AM

In case you're already on Java8, there's a LocalDateTime#ofEpochSecond() which allows you to feed epoch seconds directly without the need for multiplying into milliseconds flavor.

LocalDateTime dateTime = LocalDateTime.ofEpochSecond(seconds, 0, ZoneOffset.UTC);
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("EEEE,MMMM d,yyyy h:mm,a", Locale.ENGLISH);
String formattedDate = dateTime.format(formatter);
System.out.println(formattedDate); // Tuesday,November 1,2011 12:00,AM