Reading from hashtables

Hi all,

i am currently developing a java application that will read in a CSV
file which includes computer names and mac addresses. I have two
seperate functions within a class. One function is called readFile();
and the other function is called WOL();.

In the readFile() function it reads the CSV file in and then adds the
data into a hashtable. I then want to retrieve a computer name from
the hashtable being ran from the WOL function. However when I output
the hash table to the console it says that the table is null. When I
use the exact same code and place that within the readFile function it
works fine. The code is below:

package remoteshutdown;

import java.awt.Dimension;
import java.awt.Point;
import java.io.*;
import java.net.*;
import java.util.*;

public class WakeOnLan {
    String macStr;
// String mac;
// String Computer;
    Hashtable<String, String> macTable = new Hashtable<String,
String>();

    public static final int PORT = 9;

    public void readFile() {
        try {
            // Open the file that is the first
            // command line parameter
            FileInputStream fstream = new FileInputStream("C:\
\Documents and Settings\\All Users\\Application Data\\Remote Shutdown\
\DHCP Export.csv");
            // Get the object of DataInputStream
            DataInputStream in = new DataInputStream(fstream);
            BufferedReader br = new BufferedReader(new
InputStreamReader(fstream));
            String strLine;
            //Read File Line By Line
            while ((strLine = br.readLine()) != null) {
             System.out.println("strLine is: " + strLine );
             StringTokenizer st = new StringTokenizer(strLine, ",.");

             String Computer = st.nextToken();

             if(strLine.contains("."))
             {
             int firstIndex = strLine.indexOf(".");
             int lastIndex = strLine.lastIndexOf(".");
             if (firstIndex == lastIndex) {
             st.nextToken();
             }
             else {
         st.nextToken();
             st.nextToken();
             }
             }
             String mac = st.nextToken();
             System.out.println("\t\tComputer : " + Computer+" for
"+mac);

             macTable.put((String)Computer, (String)mac);
                // Print the content on the console
            //Close the input stream
            }
           System.out.println("CLOSING IN");
            in.close();

        } catch (Exception e) { //Catch exception if any
            System.err.println("Error: " + e.toString());

        }
    }

    public void WOL() {
     String Computer = (String)
mainScreen.lstComputerNames.getSelectedValue();

        System.out.println("the mac table has inside: " + macTable);

     String wakeComputer = (String)macTable.get("cbo_test2");

     System.out.println("wakeComputer is:" + wakeComputer);

     System.out.println("computer variable is: " + Computer);

        String ipStr = "255.255.255.255"; //broadcast address
        String macStr = "00:30:4F:1C:95:DF"; //CBO_TEST2

        try {
            byte[] macBytes = getMacBytes(macStr);
            byte[] bytes = new byte[6 + 16 * macBytes.length];
            for (int i = 0; i < 6; i++) {
                bytes[i] = (byte) 0xff;
            }
            for (int i = 6; i < bytes.length; i += macBytes.length) {
                System.arraycopy(macBytes, 0, bytes, i,
macBytes.length);
            }

            InetAddress address = InetAddress.getByName(ipStr);
            DatagramPacket packet = new DatagramPacket(bytes,
bytes.length, address, PORT);
            DatagramSocket socket = new DatagramSocket();
            socket.send(packet);
            socket.close();

            System.out.println("Wake-on-LAN packet sent.");
        }
        catch (Exception e) {
            System.out.println("Failed to send Wake-on-LAN packet: +
e");
            System.exit(1);
        }

    }

    private static byte[] getMacBytes(String macStr) throws
IllegalArgumentException {
        byte[] bytes = new byte[6];
        String[] hex = macStr.split("(\\:|\\-)");
        if (hex.length != 6) {
            throw new IllegalArgumentException("Invalid MAC
address.");
        }
        try {
            for (int i = 0; i < 6; i++) {
                bytes[i] = (byte) Integer.parseInt(hex[i], 16);
            }
        }
        catch (NumberFormatException e) {
            throw new IllegalArgumentException("Invalid hex digit in
MAC address.");
        }
        return bytes;
    }

}

Any help in this matter would be highly appreciated.

Thank you