how to time is available in milliseconds java code example

Example: date to milliseconds java

import java.time.LocalDateTime;
import java.time.ZoneId;
import java.time.format.DateTimeFormatter;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.*;

public class HelloWorld{

     public static void main(String []args){

		String myDate = "2020-02-26 03:57:35";
		LocalDateTime localDateTime = LocalDateTime.parse(myDate,
		    DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss") );
		    
		    long millis = localDateTime
		    .atZone(ZoneId.of("America/Chicago")) //optional
		    .toInstant().toEpochMilli();
    
		System.out.println(millis);
     }
}