Why console jar program does not run?

Question

Hi,
I built a console application on windows. It works fine when I run it on JBuilder. It has a timer to run the Socket Connection with another server and exchange data for every minute.
I built the archives - both native executable jar file and console exe file.
I run it in console window. It can display the first print line of the program: "Starting Data Exchange ..."
However, I did not see the data updating in both servers.
The console program seems running from connecting to local DB till printing out Starting Data Exchange ...
I am not sure whether the code insides the timertask has run or not. It is ok when I run it in JBuilder.
So, is it the timer bug or the classpath issue?
What may be the deployment problems?
Thanks for any kind advice.
public class DataEx {
   private static ConnectionPool C;
   static {
       C = PoolManager.getPoolInstance();
   public static void main(String args[])
       System.out.println("Starting Data Exchange ...");
       java.util.Timer clock = new java.util.Timer(true);
       clock.scheduleAtFixedRate(new java.util.TimerTask()
          public void run() {
            DataEx main = null;
            try {
               main = new DataEx();
            } catch (IOException e) {
                 System.out.println("Exception initialising DataEx " + e);
            main.DBConnection(); // Check new data from local DB
            if (!Vector.isEmpty()) {
              System.out.println("There are " + Vector.size() + " numbers of update data.");
              main.dataexchange(); // Connect to remote server to check new data and update
            else {
              System.out.println("There is no update data.");
        },0,60000); //run now for 60 seconds interval
}

Answer 1

Hi,
I modified the code and found where is the bug. When I run the jar program in console window.
The pop up ConfirmDialog box displayed and the console window printed:
Starting Data Exchange ...
New an instance. //able to new an instance
Prepare to connect DB. //able to call the DBConnection method.
Prepare to get connection pool. //prepare get connection with the pool
It does NOT show "Got connection pool." and print the following error:
java.lang.NullPointerException
java.util.Timer@141b571
I used MSSQL 2000 JDBC driver and it does not has problem when I run the program in JBuilder.
Did it lose the DataEx main object or it is the thread problem? What are the potential problems and how can I debug it?
Thanks for any kind advice.
Here is the updated code:
public class DataEx {
   private static ConnectionPool C;
   static {
       C = PoolManager.getPoolInstance();
   public static void main(String args[])
       System.out.println("Starting Data Exchange ...");
       java.util.Timer clock = new java.util.Timer(true);
       clock.scheduleAtFixedRate(new java.util.TimerTask()
          public void run() {
            DataEx main = null;
            try {
               main = new DataEx();
            System.out.println("New an instance.");
            } catch (IOException e) {
                 System.out.println("Exception initialising DataEx " + e);
            main.DBConnection(); // Check new data from local DB
         System.out.println("Connect DB Successfully.");
            if (!Vector.isEmpty()) {
              System.out.println("There are " + Vector.size() + " numbers of update data.");
              main.dataexchange(); // Connect to remote server to check new data and update
            else {
              System.out.println("There is no update data.");
        },0,60000); //run now for 60 seconds interval
     int nothing = JOptionPane.showConfirmDialog(null, "");
        System.out.println(clock);
    private void DBConnection(){
      System.out.println("Prepare to connect DB.");
      java.sql.Connection con = null;
      Statement stmt = null;
      try {
        System.out.println("Prepare to get connection pool.");
        con = C.getConnection();
        stmt = con.createStatement();
     System.out.println("Got connection pool.");
        String SqlStr = "select id,mdata from recordone";
        ResultSet rs = stmt.executeQuery(SqlStr);
     System.out.println("Created recordset object.");
          if (rs != null) {
            while (rs.next()) {
           VectorObj.setId(String.valueOf(rs.getInt("id")));
              VectorObj.setMData(rs.getString("mdata"));
              Vector.addElement(VectorObj);
            rs.close();
         System.out.println("Close recordset.");
     catch (java.sql.SQLException SQLE) {
        System.out.println(SQLE.getLocalizedMessage());
    }