import java.time.LocalDate;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Locale;

public class Main {
	public static void main(String args[]) {
		DateTimeFormatter dtfInput = DateTimeFormatter.ofPattern("dd-MM-uuuu", Locale.ENGLISH);
		LocalDate date = LocalDate.parse("15-08-2021", dtfInput);
		ZonedDateTime zdt = date.atStartOfDay(ZoneId.of("UTC"));
		System.out.println(zdt);

		// Custom format
		DateTimeFormatter dtfOutput = DateTimeFormatter.ofPattern("uuuu-MM-dd'T'HH:mm:ssXXX", Locale.ENGLISH);
		String formatted = dtfOutput.format(zdt);
		System.out.println(formatted);
	}
}