getTimeinMillis返回负值

Question

I am making an app which can show time left to some date, and an elapsed time after some date. But I endure some difficulties with dates less than 1970 and bigger than 3300. I have found an explanation why it happens.

The problem is this sentence from getTimeInMillis: the current time as UTC milliseconds from the epoch. And, as far as i remember, the epoch started on January 1st 1970 you get a negative number for anything before that.

My question is how to solve this problem. (And yes i have heard about JodaTime, I am not allowed to use this library in this app.)

What default(standard) tools should i use?

Here it is a piece of code that does not work properly.

private void getDateTime()
{
    Date date = new Date();

    timeRemaining = Calendar.getInstance();
    date.setTime(timeRemaining.getTimeInMillis());

    millis = Math.abs(timeRemaining.getTimeInMillis() - targetDate.getTimeInMillis());

    int scnds = (int) (millis / 1000) % 60 ;
    int mnts = (int) ((millis / (1000 * 60)) % 60);
    int hrs = (int) ((millis / (1000 * 60 * 60)) % 24);
    int dys = (int) (millis / (1000 * 60 * 60 * 24));

    resultDate.setText(getString(R.string.formating, dys, hrs, mnts, scnds));
}

Answer 1

You can achieve this by leveraging the Duration and LocalDateTime class(es) introduced in Java 8 --

import java.time.Duration;
import java.time.LocalDateTime;

class Main {
  public static void main(String[] args) {
    LocalDateTime fromDateTime = LocalDateTime.of(1914, 9, 10, 0, 0, 0);
    LocalDateTime toDateTime = LocalDateTime.of(2014, 12, 16, 0, 0, 0);
    System.out.println(Duration.between(fromDateTime, toDateTime).toMillis());
  }
}