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Converting Epoch Seconds to DMYHMS

Problem

You need to convert a number of seconds since 1970 into a `Date`.

Solution

Just use the `Date` constructor.

Discussion

“The Epoch” is the time at the beginning of time as far as modern operating systems go. Unix time, and some versions of MS-Windows time, count off inexorably the seconds since the epoch. On systems that store this in a 32-bit integer, time is indeed running out. Let’s say we wanted to find out when the Unix operating system, whose 32-bit versions use a 32-bit date, will get into difficulty. We take a 32-bit integer of all ones, and construct a `Date` around it. The `Date` constructor needs the number of milliseconds since 1970, so we multiply by 1,000:

```/** When does the UNIX date get into trouble? */

public class Y2038 {
public static void main(String[] a) {

// This should yield 2038AD, the hour of doom for the
// last remaining 32-bit UNIX systems (there will be
// millions of 64-bit UNIXes by then).

long expiry = 0x7FFFFFFFL * 1000;

System.out.println("32-bit UNIX expires on " +
Long.toHexString(expiry) + " or " +
new java.util.Date(expiry));
// Why doesn't it?

// Try going from msec of current time into a Date
long now = System.currentTimeMillis(  );
System.out.println(
"Passing " + Long.toHexString(now) + " --> " +
new java.util.Date(now));

}
}```

Sure enough, the program reports that 32-bit Unixes will expire in the year 2038 (you might think I knew that in advance if you were to judge by the name I gave the class; in fact, my ...

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