Turning timeInMills to a 24hour/Date

Question

Is there any source code for turning the timeInMills to a 24hour/Date like from the messenger app. When the timeInMills is below 24 hour it will return like this 16:15 but when it is over 24hour it will return like this THU at 16:15. I am currently creating a chat app and I want to add this to my app.

Answer 1

Edit

Beware this line: long last24hTimestamp = current - MILLISECONDS_PER_DAY;

I'm calculating on behalf of UTC time.

To get the local time, you should take into account the timezone.

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So basically you have to calculate if the timestamp timeInMillis is within the last 24h then use one format otherwise use another format.

This will help you:

public static final long MILLISECONDS_PER_DAY = 24 * 60 * 60 * 1000;// In real app you should pre-calculate this value
public static final String RECENT_DATE_FORMAT = "HH:mm";
public static final String OLD_DATE_FORMAT = "E' at 'HH:mm";

public static String displayTime(long timestamp) {
  long current = System.getCurrentTimeMillis();
  long last24hTimestamp = current - MILLISECONDS_PER_DAY;

  if (timestamp > last24hTimestamp) {

   // Received message within a day, use first format
   SimpleDateFormat sdf = new SimpleDateFormat(RECENT_DATE_FORMAT);
   return sdf.format(new Date(timestamp));
  } else {
    // Message is older than 1 day. Use second format

  }

}

Something you should take care of:

1. Consider parsing with timezone/localization if your app run in multiple places

2. If you're using java 8, try to use DateTimeFormatter. It's threadsafe and you can use a static instance per date format, no need to initialize SimpleDateFormat everytime you want to format a date