code: package cic.cs.unb.ca.jnetpcap;
  
  import java.text.SimpleDateFormat;
  import java.time.Instant;
  import java.time.LocalDateTime;
  import java.time.ZoneId;
  import java.time.format.DateTimeFormatter;
  import java.util.Date;
  
  public class DateFormatter {
  	
  	public static String parseDateFromLong(long time, String format){
  		try{
  			if (format == null){
  				format = "dd/MM/yyyy hh:mm:ss";					
  			}
  			SimpleDateFormat simpleFormatter = new SimpleDateFormat(format);
  			Date tempDate = new Date(time);
  			return simpleFormatter.format(tempDate);
  		}catch(Exception ex){
  			System.out.println(ex.toString());
  			return "dd/MM/yyyy hh:mm:ss";
  		}		
  	}
  
  	public static String convertMilliseconds2String(long time, String format) {
  
          if (format == null){
              format = "dd/MM/yyyy hh:mm:ss";
          }
  
          DateTimeFormatter formatter = DateTimeFormatter.ofPattern(format);
          LocalDateTime ldt = LocalDateTime.ofInstant(Instant.ofEpochMilli(time), ZoneId.systemDefault());
          return ldt.format(formatter);
  	}
  
  }
  