import java.time.Instant;
import java.time.LocalDateTime;
import java.time.ZoneOffset;
import java.time.format.DateTimeFormatter;
import java.util.Locale;
 
public class Main {
	public static void main(String[] args) {
		// A sample date-time string
		String dateStr = "2020-02-29 19:56:36.234";
 
		DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSS", Locale.ENGLISH);		
		LocalDateTime ldt = LocalDateTime.parse(dateStr, dtf);
 
		Instant instant = ldt.toInstant(ZoneOffset.UTC);
		System.out.println(instant);
	}
}

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