Exception in thread "main" java.lang.NoClassDefFoundError:

Hi, I've complied a program successfully but when i run i get the following error

Exception in thread "main" java.lang.NoClassDefFoundError: /users/0209126m/LAB-6/Dogs/class
Caused by: java.lang.ClassNotFoundException: .users.0209126m.LAB-6.Dogs.class
        at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:276)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)
 


The classpath is set to

.:/users/level3/software/public/DB3/jxl.jar:/users/level3/software/public/DB3/tonicpoint.jar:/users/level3/software/public/DB3/poi-3.0-alpha2-20060616.jar:/users/level3/software/public/DB3/poi-scratchpad-3.0-alpha2-20060616.jar:/users/level3/software/public/DB3/ojdbc14.jar:/users/level3/software/public/DB3/jfreechart-0.9.6.jar:/users/level3/software/public/DB3/jcommon-0.7.2.jar:/users/level3/software/public/DB3/db3.jar:
 

the program code is



/**
 *
 * @author Lindsey
 */
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import java.sql.*;

public class Dogs extends JFrame {
   //swing components
   private JButton motherButton = new JButton(),
                   fatherButton = new JButton(),
                   originalButton = new JButton("Original dog"),
                   restartButton = new JButton("Choose another dog"),
                   quitButton = new JButton("Quit");
   private JLabel dogInfo = new JLabel(),
                  pedInfo = new JLabel();
   private Stack<String> dogStack = new Stack<String>();
   private String topMother, topFather; //the mother and father names of the dog
                                        //at the top of the dogStack
   //database stuff  
   private static final String connStr =
           "jdbc:oracle:thin:your_oracle_0209126m/" +
           "0209126mtest@crooked.dcs.gla.ac.uk:1521:L3";
   private static Connection conn;
   private static PreparedStatement dogInfoStmt, siblingStmt, childStmt,
                                    grandchildStmt, parentStmt, breedStmt,
                                    parentBreedStmt;

   //output a supplied error message, the details of the exception, and then die
   private static void doError(Exception e, String msg)
   {
      System.out.println(msg);
      e.printStackTrace();
      System.exit(1);
   }
   
   //output any warnings associated with <conn> or <stmt>
   private static void printWarnings(Connection conn, Statement stmt)
   {
      try {
         SQLWarning currConnWarn = conn.getWarnings();
         while (currConnWarn != null)
            System.out.println("Warning: " + currConnWarn.getMessage());
         SQLWarning currStmtWarn = stmt.getWarnings();
         while (currStmtWarn != null)
            System.out.println("Warning: " + currStmtWarn.getMessage());
      } catch(Exception e) {
         doError(e, "Problem getting warnings");
      }
   }
   private Dogs() {
      //database stuff - load driver, and then obtain connection
      try {
        Class.forName("oracle.jdbc.driver.OracleDriver");
      } catch(Exception e) {
         doError(e, "Failed to load oracle driver");
      }
      try {
        Connection conn = DriverManager.getConnection(connStr);
      } catch(Exception e) {
         doError(e, "Failure to obtain connection: " + connStr);
      }
      //create prepared statements for later use by the interface code
      //this will form a nested query to tell us how many dogs an owner has
      //Columns should be renamed, if necessary
      //Result: ownerid, noOfDogs
      String ownerCount =
              "SELECT ownerid, Count(name)" +
          "FROM Dog " +
          "GROUP BY ownerid";
      //finds all the data that are single values per dog
      String dogInfoQuery =
                   "SELECT Dog.breedname, Dog.mothername, " +
                   "       Dog.fathername, Kennel.kennelname, " +
                   "       Kennel.address, Owner.name, " +
                   "       OwnerCount.noOfDogs " +
                   "FROM Dog, Kennel, " +
                   "     Owner, (" + ownerCount + ") OwnerCount " +
                   "WHERE Dog.kennelname=Kennel.kennelname AND " +
                   "      Dog.ownerid=Owner.ownerid AND " +
                   "      Owner.ownerid=OwnerCount.ownerid AND " +
                   "      Dog.name=?"; //parameterised by dog name
      try {
         dogInfoStmt = conn.prepareStatement(dogInfoQuery);
      } catch(SQLException e) {
         doError(e, "Dog info statement failed to compile: " + dogInfoQuery);
      }
      //finds the dog's siblings (incl. half siblings), but not the dog itself
      //parameterised by (1) the dog's mothername, (2) the dog's fathername and (3) the dog's
      //own name
      //Result: name
      String siblingQuery =
              "SELECT d2.name" +
              "FROM Dog d1, Dog d2" +
              "WHERE (d1.mothername=d2.mothername)" +
              "OR d1.fathername=d2.fathername)" +
              "AND d1.name=?" +
              "AND d2.name<>d1.name";
     
      try {
         siblingStmt = conn.prepareStatement(siblingQuery);
      } catch(SQLException e) {
         doError(e, "Sibling statement failed to compile: " + siblingStmt);
      }
//finds the dog's children, we don't know if it's a mother or father, so
      //we match either (although presumably only one for any given dog!)
      //the query should be parametrised by (1) the dog's mothername, and (2) the dog's fathername
      //Result: name
      //Sorted by: name
      String childQuery =
              "SELECT name"+
              "FROM Dog"+
              "WHERE mothername = ?" +
              "OR fathername = ?";
      try {
         childStmt = conn.prepareStatement(childQuery);
      } catch(SQLException e) {
         doError(e, "Child query failed to compile: " + childQuery);
      }
      //finds the dog's grandchildren, again matching father or mother as above
      //in this query the current dog "?" is D1's mother or father, D2 is the
      //grandchild.
      //Result: D2.name
      String grandchildQuery =
              "SELECT d2.name " +
              "FROM Dog d1, Dog d2" +
              "WHERE (d1.mothername = ? OR d1.fathername = ?" +
              "AND (d1.name = d2.mothername OR d1.name = d2.fathername)";
      try {
         grandchildStmt = conn.prepareStatement(grandchildQuery);
      } catch(SQLException e) {
         doError(e, "Granchild query failed to compile: " + grandchildQuery);
      }
      //finds parents of two dogs at once, the parameters are the two dogs
     
      String parentQuery = "SELECT mothername, fathername " +
                           "FROM Dog " +
                           "WHERE name=? OR name=?";
      try {
         parentStmt = conn.prepareStatement(parentQuery);
      } catch(SQLException e) {
         doError(e, "Failed to compile grandparent statement: " + parentQuery);
      }
      //a query to return all known breeds for the supplied dog, used in
      //getParentsBreeds()
 
      String parentBreedQuery = "SELECT Parent.breedname " +
                                "FROM Dog Curr, Dog Parent " +
                                "WHERE (Curr.mothername=Parent.name OR " +
                                "       Curr.fathername=Parent.name) " +
                                "  AND Curr.name=?";
      try {
         parentBreedStmt = conn.prepareStatement(parentBreedQuery);
      } catch(SQLException e) {
         doError(e, "Failed to compile parent breed stmt: " + parentBreedStmt);
      }
//info text boxes and labels
      JPanel dogInfoPanel = new JPanel();
      dogInfoPanel.add(dogInfo);
      dogInfoPanel.setBorder(
         BorderFactory.createCompoundBorder(
            BorderFactory.createTitledBorder("Dog information"),
            BorderFactory.createEmptyBorder(10,10,10,10)));
      JPanel pedInfoPanel = new JPanel();
      pedInfoPanel.add(pedInfo);
      pedInfoPanel.setBorder(
         BorderFactory.createCompoundBorder(
            BorderFactory.createTitledBorder("Pedigree"),
            BorderFactory.createEmptyBorder(10,10,10,10)));
      //positioning of components
      Container cp = getContentPane();
      cp.setLayout(new BoxLayout(cp,BoxLayout.X_AXIS));
      Box buttonBox = Box.createVerticalBox();
      buttonBox.add(motherButton);
      buttonBox.add(fatherButton);
      buttonBox.add(originalButton);
      buttonBox.add(Box.createVerticalGlue());
      buttonBox.add(restartButton);
      buttonBox.add(quitButton);
      Box infoBox = Box.createVerticalBox();
      infoBox.add(dogInfoPanel);
      infoBox.add(pedInfoPanel);
      cp.add(infoBox);
      cp.add(buttonBox);
      //button handling
      ButtonHandler bh = new ButtonHandler();
      motherButton.addActionListener(bh);
      fatherButton.addActionListener(bh);
      originalButton.addActionListener(bh);
      restartButton.addActionListener(bh);
      quitButton.addActionListener(bh);
      //set up the dog to be displayed
      dogStack.push(getDogChoice());
      redisplay(); //display dog info
      originalButton.setEnabled(false); //cannot go to previous dog
      //window settings
      Dimension screen = getToolkit().getScreenSize();
      setBounds(0, 0, 700, 700); //position (0,0) and size 700x700
      setDefaultCloseOperation(EXIT_ON_CLOSE);
      setTitle("Dog information");
      setVisible(true);
   }



   //Returns the most accurate possible breed information for the supplied dog's
   //parents. For a parent that is not in the database we will assume that the
   //breed is the same as the supplied dog's, unless the supplied dog is not in
   //the database in which case we assume <assumeBreed>.
   private Vector<String> getParentBreeds(String dogname, String assumeBreed)
   {
      Vector<String> retval = new Vector<String>(); //breeds we've found
      //get as many parent breeds as possible
      try {
         parentBreedStmt.setString(1, dogname);
         ResultSet results = parentBreedStmt.executeQuery();
         printWarnings(conn, parentBreedStmt);
         //Get all the breed information available from the database.
         //Due to key constraints there are at most 2 rows in the result.
         while (results.next())
            retval.add(results.getString(1));
      } catch(SQLException e) {
         doError(e, "Parent breed query failed to execute");
      }
      //if we have all the possible parents, then we can stop now, otherwise use
      //best guesses as per the comment above
      if (retval.size() == 2)
         return retval;
      else {
         try {
            dogInfoStmt.setString(1, dogname);
            ResultSet results = dogInfoStmt.executeQuery();
            printWarnings(conn, dogInfoStmt);
            if (results.next()) //try to use the supplied dog's real breed
               while (retval.size() < 2)
                  retval.add(results.getString(1));
            else //if real breed is not available use the assumed breed
               while (retval.size() < 2)
                  retval.add(assumeBreed);
         } catch(SQLException e) {
            doError(e, "Failed to execute breed query");
         }
      }
      return retval;
   }

   //displays the dog data present on the top of the stack of names
   private void redisplay() {
      if (dogStack.empty()) {
         System.out.println("Unexpectedly exhausted dogs!");
         System.exit(1);
      }
      String dogName = dogStack.peek();
      ResultSet results;
      //per-dog information
      String name = null, breed = null, mother = null, father = null,
             kennel = null, kennAddr = null, owner = null;
      int ownerDogs = 0;
      //information with arbitrary numbers of values per dog
      Vector<String> siblings = new Vector<String>(),
                     children = new Vector<String>(),
                     grandchildren = new Vector<String>(),
                     grandparents = new Vector<String>();
      try {
         dogInfoStmt.setString(1, dogName);
         results = dogInfoStmt.executeQuery();
         printWarnings(conn, dogInfoStmt);
         //make sure that the dog we are trying to display is in the DB
         if (!(results.next())) {
            //remove it and display a warning message
            JOptionPane.showMessageDialog(this,
               "Information for " + dogStack.pop() + " missing in database.");
            if (dogStack.size() == 1) //in case there is no stack to ascend
               originalButton.setEnabled(false);
            return; //stop now
         }
         //since the data is in the database we continue as normal
         breed = results.getString(1);
         topMother = mother = results.getString(2);
         topFather = father = results.getString(3);
         kennel = results.getString(4);
         kennAddr = results.getString(5);
         owner = results.getString(6);
         ownerDogs = results.getInt(7);
      } catch(SQLException e) {
         doError(e, "Failed to execute dog info query for " + dogName);
      }
      try {
         //looking for dogs with the same parents
         siblingStmt.setString(1, mother);
         siblingStmt.setString(2, father);
         siblingStmt.setString(3, dogName); //don't match the dog itself
         results = siblingStmt.executeQuery();
         printWarnings(conn, siblingStmt);
         while (results.next()) //store each sibling name for later display
            siblings.add(results.getString(1));
      } catch(SQLException e) {
         doError(e, "Failed to execute sibling query for " + dogName);
      }
      try {
         //looking for child dogs
         childStmt.setString(1, dogName); childStmt.setString(2, dogName);
         results = childStmt.executeQuery();
         printWarnings(conn, childStmt);
         while (results.next()) //store each name for display later on
            children.add(results.getString(1));
      } catch(SQLException e) {
         doError(e, "Failed to execute child query for " + dogName);
      }
      try {
         //looking for grandchildren
         grandchildStmt.setString(1, dogName);
         grandchildStmt.setString(2, dogName);
         results = grandchildStmt.executeQuery();
         printWarnings(conn, grandchildStmt);
         while (results.next())
            grandchildren.add(results.getString(1));
      } catch(SQLException e) {
         doError(e, "Failed to execute grandchild query for " + dogName);
      }
      try {
         parentStmt.setString(1, mother); //maternal grandparents
         parentStmt.setString(2, father); //and paternal grandparents
         results = parentStmt.executeQuery();
         printWarnings(conn, parentStmt);
         while (results.next()) { //zero, one or two rows as a result
            if (results.getString(1) != null)
               grandparents.add(results.getString(1)); //grandmother
            if (results.getString(2) != null)
               grandparents.add(results.getString(2)); //grandfather
         }
      } catch(SQLException e) {
         doError(e, "Failed to execute grandparent query for " + dogName);
      }


      Vector <String> ancestors = getAncestors(dogName,null);
      Vector <String> des = getDescendents(dogName,null);


      if (kennAddr == null) kennAddr = "Unknown";

      //output dog info data
      dogInfo.setText("<html>Name: " + dogName + "<br>" +
                      "Breed: " + breed + "<br>" +
                      "Kennel: " + kennel + "<br>" +
                      "Address: " + kennAddr + "<br>" +
                      dogName + "'s owner: " +
                      owner + " (owns " + ownerDogs + " dogs)" + "</html>");
      //put together a message about how many parents are not named in the DB
      String parentMissingInfo = ""; //nothing by default
      if (father == null && mother == null)
         parentMissingInfo = "(2 missing)";
      else if (father == null ^ mother == null) //exclusive OR
         parentMissingInfo = "(1 missing)";
      //message about how many grandparents are missing, assume dog isn't inbred
      String grandparentMissingInfo = "";
      if (grandparents.size() != 4)
         grandparentMissingInfo = "(" + (4 - grandparents.size()) + " missing)";
      //put together the required breed information



      Vector<String> breeds = getParentBreeds(mother, breed);
      breeds.addAll(getParentBreeds(father, breed));
      breeds.add("ZZZZZZZZZZZZZZZZZZZZZZZZ"); //sentinel to help the output code


      Object[] breedStrings = breeds.toArray();
      Arrays.sort(breedStrings);
      boolean isPureBred = breedStrings[0] == breedStrings[1] &&
                           breedStrings[1] == breedStrings[2] &&
                           breedStrings[2] == breedStrings[3];
      String breedingString = "";
      for (int i = 0; i < 4; i++)
         for (int j = i; j < 5; j++)
            if (!(breedStrings[i].equals(breedStrings[j]))) {
               breedingString += "(" + (j - i) + "/4 " + breedStrings[i] + ") ";
               i = j - 1; //start again at the start of the next run of breeds
               break;
            }
      //output pedigree info
      pedInfo.setText("<html>" + dogName + "'s siblings: " + siblings + "<br>" +
                      dogName + "'s Parents: " +
                      (father != null ? father : "") +
                      (father != null && mother != null ? ", " : "") +
                      (mother != null ? mother : "") +
                      " " + parentMissingInfo +
                      "<br>" + dogName + "'s Grandparents: " + grandparents +
                      " " + grandparentMissingInfo +
                      "<br>" + dogName + "'s Children: " + children + "<br>" +
                      dogName + "'s Grandchildren: " + grandchildren +
                      "<br><br>" +
                      (isPureBred ? "Purebred<br>" : "Not purebred<br>") +
                      "Breeding: " + breedingString +
                      "</html>");
      if (mother != null)
         motherButton.setText(mother + "'s details");
      else {
         motherButton.setText("Not available");
         motherButton.setEnabled(false);
      }
      if (father != null)
         fatherButton.setText(father + "'s details");
      else {
         fatherButton.setText("Not available");
         fatherButton.setEnabled(false);
      }
   }

   //gets a dog name that the user chooses somehow
   private String getDogChoice() {
      try {
         Statement dogStmt = conn.createStatement();
         ResultSet dogRes = dogStmt.executeQuery("SELECT name " +
                                                 "FROM Dog " +
                                                 "ORDER BY name");
         Vector<String> dogNames = new Vector<String>();
         while (dogRes.next())
            dogNames.add(dogRes.getString(1));
         if (dogNames.size() == 0) {
            System.out.println("No dogs present in database, exiting.");
            System.exit(1);
         }
         String choice;
         do {
            //use a modal JOptionPane dialog to let the user choose between dogs
            choice = (String)(JOptionPane.showInputDialog(this, //parent dialog
                                            "Select a dog to view", //message
                                            "Select a dog", //title of dialog
                                            JOptionPane.PLAIN_MESSAGE, //urgency
                                            null,
                                            dogNames.toArray(), //choices
                                            dogNames.get(0))); //default choice
         } while (choice == null); //keep going until the user picks one
         return choice;
      } catch(SQLException e) {
         doError(e, "Failed to get dog name choices from DB");
      }
      return null; //unreachable
   }

   //handler to do the work of all the buttons, namely the parent buttons, the
   //back button and the exit button
   private class ButtonHandler implements ActionListener {
      public void actionPerformed(ActionEvent ae) {
         Object src = ae.getSource(); //the button that causes the event
         if (src == motherButton) {
            dogStack.push(topMother); //put mother at the top of the stack
            originalButton.setEnabled(true);
            motherButton.setEnabled(true);
            fatherButton.setEnabled(true);
            redisplay(); //refresh the details on screen to show the mother
         } else if (src == fatherButton) {
            dogStack.push(topFather);
            originalButton.setEnabled(true);
            motherButton.setEnabled(true);
            fatherButton.setEnabled(true);
            redisplay();
         } else if (src == originalButton) {
            dogStack.pop(); //discard currently displayed dog
            if (dogStack.size() == 1)
               originalButton.setEnabled(false); //can't go any further back
            motherButton.setEnabled(true);
            fatherButton.setEnabled(true);
            redisplay();
         } else if (src == restartButton) {
            dogStack.clear();
            dogStack.push(getDogChoice());
            redisplay();
         } else if (src == quitButton) {
            try {
               conn.close();
            } catch(SQLException e) {
               System.out.println("Cannot close DB connection");
               e.printStackTrace();
            } finally {
               System.exit(0);
            }
         }
      }
   }

   public static void main(String[] args) {
      Dogs window = new Dogs();
   }

    private Vector<String> getAncestors(String dogname, Vector<String> anc) {
      if (anc == null) anc = new Vector<String>();

      try {
          // INSERT CODE HERE TO GET ANCESTORS
      }
      catch(Exception e) {
            doError(e, "Failed to execute ancestor query in getBreeding");
      }
      return anc;
      
    }





    private Vector<String> getDescendents(String dogname, Vector<String> anc) {
      if (anc == null) anc = new Vector<String>();

      try {
          //INSERT CODE HERE TO FIND DESCENDENTS

      }
      catch(Exception e) {
            doError(e, "Failed to execute ancestor query in getBreeding");
      }
      return anc;
      
    }

}



     
HELP!!