import java.net.*;
import java.io.*;
import java.util.*;

public class TimeClient {
        
  public final static int DEFAULT_PORT = 37;

  public static void main(String[] args) {

    String hostname;
    int port = DEFAULT_PORT;
    
    if (args.length > 0) {
      hostname = args[0];
    }
    else {
      hostname = "tock.usno.navy.mil";
    }

    if (args.length > 1) {
      try { 
        port = Integer.parseInt(args[1]);
      }
      catch (NumberFormatException e) {
      } 
    }
    
    // The time protocol sets the epoch at 1900,
    // the java Date class at 1970. This number 
    // converts between them.
    
    long differenceBetweenEpochs = 2208988800L;
    
    // If you'd rather not use the magic number uncomment 
    // the following section which calculates it directly.
    
    /*    
    TimeZone gmt = TimeZone.getTimeZone("GMT");
    Calendar epoch1900 = Calendar.getInstance(gmt);
    epoch1900.set(1900, 01, 01, 00, 00, 00);
    long epoch1900ms = epoch1900.getTime().getTime();
    Calendar epoch1970 = Calendar.getInstance(gmt);
    epoch1970.set(1970, 01, 01, 00, 00, 00);
    long epoch1970ms = epoch1970.getTime().getTime();
    
    long differenceInMS = epoch1970ms - epoch1900ms;
    long differenceBetweenEpochs = differenceInMS/1000;
    */    
    
    InputStream raw = null;
    try {
      Socket theSocket = new Socket(hostname, port);
      raw = theSocket.getInputStream();
      
      long secondsSince1900 = 0;
      for (int i = 0; i < 4; i++) {
        secondsSince1900 = (secondsSince1900 << 8) | raw.read();
      }

      long secondsSince1970 
       = secondsSince1900 - differenceBetweenEpochs;       
      long msSince1970 = secondsSince1970 * 1000;
      Date time = new Date(msSince1970);
      
      System.out.println("It is " + time + " at " + hostname);
  
    }  // end try
    catch (UnknownHostException e) {
      System.err.println(e);
    }
    catch (IOException e) {
      System.err.println(e);
    }
    finally {
      try {
        if (raw != null) raw.close(); 
      }
      catch (IOException e) {}
    }

  }  // end main

} // end TimeClient