Runtime Error - NullPointerException

Question

I am not quite sure where to start
but I will do my best to not have it turn into ramble.
First I want to check for an "old" open DB connection
and close it if there is one open
Now where my error occurs:
Then in the while (connected == false)
loop, I delete all of the data out of the tables
because I do not want stale data appearing on the GUI.
For some reason this is where is throws my error.
If I take them out it runs fine.
The real strange deal is I have another program
set up to read from a processor the same way
and that one throws no errors at all.
So I am thinking (okay hoping) its just something small I am missing
Thank you very much for all of your time
January
import java.net.*;
import java.sql.*;
import java.util.*;
import java.io.*;
public class Example{
//SOMEWHWER AT THE BEGINNING OF THE CLASS
static PreparedStatement psDELtblRtFields;
  static PreparedStatement psVIP_Connection_Down;
   static PreparedStatement psDELETE_tblRtFieldsMsgBlkHeaders;
  static PreparedStatement psDELETE_tblRtFieldsType1;
public static void processing_loop() {
     //constants read from a config file
    ServerSocket echoServer = null;
    Socket clientSocket     = null;
    String IP_ADDRESS       = VIP_IP_ADDRESS;  // VIP computer
    int SOCKET_NUMBER       = VIP_DATA_SOCKET_NUMBER; //constants read from a config file
    boolean connected       = false; //variable to help robustness of connection
    boolean socket_error    = false;
    //  Writing to MySql Database declarations
    java.sql.Connection conn = null;
   String DELETE_tblRtFields = "UPDATE tblRtFields SET gps_sow=0, " +
         "gps_week=0, intVipMode=0,DblOutputPower=0,     DblFrequency=0, intVipBit=0, intTxFail=1," +
         "intMonFail=1, intVote_mismatches=0, intVip_voter_fault=1, intAti_error_count=0," +
         "intAti_fault=1, intMystery_msg_count=0, intMystery_msg_fault=1, "+
         "intMissed_msg_count=0, intVip_mer_fault=1, intVip_no_xmit_fault=1, " +
         "strTx_status=0, intTx_outrange=0, intVip_Tx_power_fault=1, intVip_Tx_power_offset=0, "+
         "intMon_bit_results=1, intTx_bit_results=1, dblCurrent_Temp=0, intTemp_color=1, dblMon_power=0, " +
         "strMon_status=0 WHERE ID = 1";
    //DONE 12-17-04
    String DELETE_tblRtFieldsType1     =     " UPDATE tblRtFields SET gps_sow = 0, " +          //DONE 12-17-04
               "gps_week=0, intModz=0, intNum_of_meas=0, intMeas_type=0 "+
               "WHERE ID=1";
               //5 total entries
     String DELETE_tblRtFieldsMsgBlkHeaders = "UPDATE tblRtFields SET gps_sow=0, "+  //DONE 12-17-04
               "gps_week=0, strStation_id=0 "+
               "WHERE ID=1";
          // 3 total entries
    String VIP_Connection_Down = "UPDATE tblIcs SET connection_up=0 WHERE connection_id=19";
    // main processing starts here
    try {
      // register Database driver
      Class.forName(SQL_DRV);
    } catch(java.lang.ClassNotFoundException e) {
      System.err.print("ClassNotFoundException: ");
      System.err.println(e.getMessage());
    } finally {
      try {
        conn.close();
      } catch
        (Exception e) {}
    } // end finally
    while ( true ) {  // this is the forever loop
      if ( connected == true ) { //old connection - close it
        try{
          clientSocket.close();
          connected = false;
          System.out.println("Closing socket");
        } catch (IOException ey){
          System.out.println(ey);
          continue;
        }//end try
      } //end if connected == true
      //IT THROWS THE ERROR HERE, IF I TAKE ALL OF THE STUFF OUT
      //(i.e. all of the prepared statements in that 2nd try block)
      //THEN IT WORKS FINE.
      while ( connected == false ) {
        try{
               try{
                    psDELtblRtFields.executeQuery();
                    psDELETE_tblRtFieldsType1.executeQuery();
                    psDELETE_tblRtFieldsMsgBlkHeaders.executeQuery();
                    psVIP_Connection_Down.executeQuery();
               catch(SQLException ex){
                    System.err.println("SQLException for Blanking tblRtFields: " + ex.getMessage());
                    ex.printStackTrace();
          // Connect to socket and listen to it
          //CONSTANTS read from a config file
          clientSocket = new Socket(IP_ADDRESS,SOCKET_NUMBER);
          connected = true;
        } catch (IOException e) {
          System.out.println("Exception caught at line 2211 " + e);
          System.out.println("Attempting to make new connection");
         try{
            Thread.currentThread().sleep(2000);
          } catch (InterruptedException es){
            //System.out.println(es);
          if ( killFile.exists() ) {
            System.out.println("VDL killed");
            //WrapperManager.stop(0);
            System.exit(0);
          //continue;
        }//end try socket connection
      } //end while connected == false
      while ( connected == true ) {
        // the following code is simply to detect when the socket goes down
        if ( socket_error == true ) {
          socket_error = false; // initialize for next time
          //break out of this loop
          break;
        try{
        conn = DriverManager.getConnection(SQL_URL, USERNAME, PASSWORD);
        //SQL statements
                    psVIP_Connection_Down = conn.prepareStatement(VIP_Connection_Down);  //DONE 10-21-04
                    //RtFields
                    psDELtblRtFields = conn.prepareStatement(DELETE_tblRtFields);  //DONE 10-21-04
                  psDELETE_tblRtFieldsType1 = conn.prepareStatement(DELETE_tblRtFieldsType1);
                  psDELETE_tblRtFieldsMsgBlkHeaders = conn.prepareStatement(DELETE_tblRtFieldsMsgBlkHeaders);
          try{
            // make input stream
            is = new BufferedReader
              (new InputStreamReader(clientSocket.getInputStream()));
             try{  //get timeout seconds from maintConfigData file
                    clientSocket.setSoTimeout(SOCKET_TIMEOUT);  //If no data is received from the socket in x amt of seconds...
                catch (SocketException se){
                     System.err.println ("Unable to set socket option SO_TIMEOUT");
            //OKAY ALL THE CRAP FROM HERE DOWN TO END OF LOOP IS JUST STUFF.............
            // As long as we receive data, keep reading
            while (true) {
             try{
                    //Code here to read from socket and store data
              } catch (RuntimeException ex){
                System.out.println("RuntimeException ex: " + ex);
                socket_error = true;
                ex.printStackTrace();
                break;
            } // end while True
          } catch (IOException e) {
            System.out.println(e);
            //e.printStackTrace();
            break;
          }//end try make input stream
          }catch (SQLException ex){
               System.err.println(
          "SQLException: 2175" + ex.getMessage());
      } //end while connected == true
    } //end while true Main Loop
  }//end processing_loop()
public static void main(String args[]){
     Example ex = new Example();
     ex.processing_loop();
}

Answer 1

The null pointer exception should be providing you with a stack trace. That tells you the exact line that the problem is on.
Note also that your code is doing to much. You should have code (a class) that does the database stuff all by itself. And then other code that does the socket stuff (a class).
You are also catching exceptions and then continuing down the same path that would have happened if the exception had not occurred. That is problematic.