Convert two separate fields Date and time fields to milliseconds

Question

I have two separate fields Date and Time fields. I would like to convert these fields into seconds format.

I am using this seonds format to make google API call.

https://maps.googleapis.com/maps/api/directions/json?
origin=Brooklyn&destination=Queens
&departure_time=1343641500&mode=transit
&key=YOUR_API_KEY

Field1: Date: 2/18/2020 Field2: Time: 9.00 AM

Expected: Field3: Seconds: 1582078857 or possible with Apex itself?

And also is there a way we can preserve same time for any timezone user?

Answer 1

If you're simply trying to get the epoch, you can use the Datetime.getTime() method.

getTime()
Returns the number of milliseconds since January 1, 1970, 00:00:00 GMT represented by this DateTime object.

Here's an anonymous script to get you started:

Datetime timestamp = Datetime.newInstance(
    Date.newInstance(2020, 18, 2),
    Time.newInstance(9, 0, 0, 0)
);
system.debug(timestamp.getTime());

USER_DEBUG [5]|DEBUG|1622649600000