Optimizing a program (experts with a lot of time)

Question

The following code is most of the code for a sale program. This is something i have been working on for a while now and it's almost finished. It does work, and with no errors that I have found so far, but it seems too complicated and long. I am asking that some of you more experienced programmers take a look at it and give me some advice or tips. It's quite a bit of code, so you don't have to look at all of it, just whatever you see.
This is the super class. It will soon be a full Log In for cashiers but right now it is just has two buttons for running the other two classes. It contains the open and save file methods that the others use to open the inventory file.
/** Java core packages*/
import java.util.*;
import java.text.*;
import java.awt.*;
import java.awt.event.*;
/** Java extension packages*/
import javax.swing.*;
import javax.swing.text.*;
import javax.swing.event.*;
import java.io.*;
/** This program is used to calculate the sale price
* of selected items and update the inventory with
* each sale. It opens and saves into a file "inventory.dat".
* @author Davin Green
public class LogIn extends JFrame
    /** JTextField objects for the text fields that are used in these programs.*/
    public JTextField jTextField1, jTextField2, jTextField3,
                       jTextField4, jTextField5, jTextField6;
    /** JButton objects for the buttons that are used in these programs.*/
    public JButton jButton1, jButton2, jButton3, jButton4,
                    jButton5, jButton6, jButton7;
    /** JScrollPane object for the scrolling pane that is used in this program.*/
    public JScrollPane jScrollPane1, jScrollPane2;
    /** Label objects for the labels that are used in these programs.*/
    public Label label1, label2, label3, label4,
                  label5, label6, label7;
    /** Vector objects for the three vectors that are used in these programs.*/
    public Vector id, qty, price, saleItems, saleItemsQty;
    /** JList object for the list of Items from vector id used in this program.*/
    public JList jList1;
    private double salePrice;
    /** Document objects for the three text fields that are used in this program.*/
    public Document jText1, jText2, jText3;
    /** DeciamlFormat object used to format display of money.*/
    private DecimalFormat toMoney;
    /** ObjectInputStream object for later inputing a stream.*/
    private ObjectInputStream objectInput;
    /** ObjectOutputStream object for later outputing a stream.*/
    private ObjectOutputStream objectOutput;
    private static LogIn window;
    public static void main( String args[] )
      window = new LogIn();
      window.setSize(450, 400);
      window.show();
    public LogIn()
        /** Get JFrames content pane and set layout to null.*/
        Container container = getContentPane();
        container.setLayout( new FlowLayout() );
        jButton1 = new JButton();
        jButton1.setText("Inventory Editor");
        container.add(jButton1);
        jButton2 = new JButton();
        jButton2.setText("Make Sale");
        container.add(jButton2);
      jButton1.addActionListener(
       new ActionListener()
         public void actionPerformed( ActionEvent event )
           Inventory inventory = new Inventory();
           inventory.runInventory();
           window.hide();
           window = null;
      jButton2.addActionListener(
       new ActionListener()
         public void actionPerformed( ActionEvent event )
           Computer computer = new Computer();
           computer.runComputer();
           window.hide();
           window = null;
    public LogIn( String title )
      super( title );
    /** The openFile() method opens inventory.dat and saves it's information into three vectors.*/
    public void openFile() throws IOException, ClassNotFoundException
      Item item;
      toMoney = new DecimalFormat( "0.00" );
      id = new Vector();
      qty = new Vector();
      price = new Vector();
     try {
          int i = 0;
          /** Opens file inventory.dat and saves data into buffer.*/
          try {
            objectInput = new ObjectInputStream( new FileInputStream( "C:/inventory.dat" ) );
          catch ( FileNotFoundException fnfException )
            objectOutput = new ObjectOutputStream( new FileOutputStream( "C:/inventory.dat" ) );
            objectOutput.close();
            objectInput = new ObjectInputStream( new FileInputStream( "C:/inventory.dat" ) );
            JOptionPane.showMessageDialog( null, "Inventory file has been created.", "File Created", JOptionPane.INFORMATION_MESSAGE );
          while ( true )
            /** Reads one item object from inventory.dat.*/
            item = ( Item ) objectInput.readObject();
            String idString = item.getID();
            String qtyString = "" + item.getQty();
            String priceString = "" + toMoney.format (item.getPrice());
            id.add( i, idString );
            qty.add( i, qtyString );
            price.add( i, priceString );
            i++;
      /** Closes file when end of file is reached.*/
      catch ( EOFException eofException )
         objectInput.close();
    /** The Method exitForm() sets what to do when window is closed.*/
    public void saveFile() throws IOException
     /** Makes file inventory.dat.*/
     objectOutput = new ObjectOutputStream( new FileOutputStream( "C:/inventory.dat" ));
     /** Saves three vectors as objects of the Item class into inventory.dat.*/
     for ( int i = 0; i < id.size(); i++ )
     String idString = (String)id.get(i);
     int qtyInt = Integer.parseInt( (String)qty.get(i) );
     double priceDouble = Double.parseDouble( (String)price.get(i) );
     Item item = new Item( idString, qtyInt, priceDouble );
     objectOutput.writeObject( item );
     /** Closes inventory.dat.*/
     objectOutput.close();
}This is the computer class. It is used to calculate sale prices and print the reciept for each sale. It does everything it's supposed to except update the inventory, which I just haven't written the code for yet.
/** Java core packages*/
import java.util.*;
import java.text.*;
import java.awt.*;
import java.awt.event.*;
/** Java extension packages*/
import javax.swing.*;
import javax.swing.text.*;
import javax.swing.event.*;
import java.io.*;
/** This program is used to calculate the sale price
* of selected items and update the inventory with
* each sale. It opens and saves into a file "inventory.dat".
* @author Davin Green
public class Computer extends LogIn
    private double salePrice;
    private JTextArea jTextArea1;
    private Choice choice1;
    private JSeparator jSeparator1;
    private static Computer window;
    /** Default constructor.*/
    public Computer()
      super("Sale Program");
      try{
        try {
          openFile();
          createGUI();
          registerCompEventHandlers();
          salePrice = 0.0;
        catch ( ClassNotFoundException e )
      catch ( IOException e )
    /** The createGUI() methods creates and displays GUI components in the JFrame.*/
    private void createGUI()
        jList1 = new JList();
        saleItems = new Vector();
        saleItemsQty = new Vector();
        /** Get JFrames content pane and set layout to null.*/
        Container container = getContentPane();
        container.setLayout(null);
        choice1 = new Choice();
        makeChoiceMenu();
        container.add(choice1);
        choice1.setBounds(40, 50, 130, 20);
        jButton1 = new JButton();
        jButton1.setText("Add Item");
        container.add(jButton1);
        jButton1.setBounds(270, 50, 130, 20);
        jButton2 = new JButton();
        jButton2.setText("Remove Item");
        container.add(jButton2);
        jButton2.setBounds(270, 80, 130, 20);
        jButton2.setEnabled( false );
        jButton3 = new JButton();
        jButton3.setText("Print Reciept");
        container.add(jButton3);
        jButton3.setBounds(270, 110, 130, 20);
        jButton3.setEnabled( false );
        jButton4 = new JButton();
        jButton4.setText("New Sale");
        container.add(jButton4);
        jButton4.setBounds(270, 140, 130, 20);
        jButton4.setEnabled( false );
        jButton5 = new JButton();
        jButton5.setText("Change Cashier");
        container.add(jButton5);
        jButton5.setBounds(410, 240, 130, 20);
        jButton6 = new JButton();
        jButton6.setText("Edit Inventory");
        container.add(jButton6);
        jButton6.setBounds(410, 270, 130, 20);
        jButton7 = new JButton();
        jButton7.setText("Edit Qty");
        container.add(jButton7);
        jButton7.setBounds(100, 80, 100, 20);
        jButton7.setEnabled( false );
        jScrollPane1 = new JScrollPane();
        jTextArea1 = new JTextArea();
        container.add(jScrollPane1);
        jScrollPane1.setBounds(10, 190, 390, 100);
        jScrollPane2 = new JScrollPane();
        jScrollPane2.getViewport().add( jList1 );
        container.add(jScrollPane2);
        jScrollPane2.setBounds(410, 40, 130, 190);
        jSeparator1 = new JSeparator();
        container.add(jSeparator1);
        jSeparator1.setBounds(10, 40, 390, 10);
        jTextField1 = new JTextField();
        jTextField1.setEditable(false);
        jTextField1.setText("Cashier Name");
        container.add(jTextField1);
        jTextField1.setBounds(60, 10, 170, 20);
        jTextField2 = new JTextField();
        jTextField2.setEditable(false);
        jTextField2.setBounds(240, 10, 80, 20);
        jTextField3 = new JTextField();
        jTextField3.setEditable(false);
        DateFormat dateFormat = DateFormat.getDateInstance(DateFormat.SHORT);
        jTextField3.setText(dateFormat.format(new Date()));
        container.add(jTextField3);
        jTextField3.setBounds(330, 10, 70, 20);
        jTextField4 = new JTextField();
        jTextField4.setText("");
        container.add(jTextField4);
        jTextField4.setBounds(60, 80, 30, 20);
        jText1 = jTextField4.getDocument();
        jTextField5 = new JTextField();
        jTextField5.setText("$0.00");
        container.add(jTextField5);
        jTextField5.setBounds(100, 140, 100, 20);
        jTextField6 = new JTextField();
        jTextField6.setEditable(false);
        jTextField6.setText("$0.00");
        container.add(jTextField6);
        jTextField6.setBounds(100, 110, 100, 20);
        label1 = new Label();
        label1.setText("Cashier");
        container.add(label1);
        label1.setBounds(10, 10, 48, 20);
        label2 = new Label();
        label2.setText("Item");
        container.add(label2);
        label2.setBounds(10, 50, 28, 20);
        label3 = new Label();
        label3.setText("Selected Item");
        container.add(label3);
        label3.setBounds(410, 20, 90, 20);
        label4 = new Label();
        label4.setText("Reciept");
        container.add(label4);
        label4.setBounds(10, 170, 50, 20);
        label5 = new Label();
        label5.setText("Quantity");
        container.add(label5);
        label5.setBounds(10, 80, 50, 20);
        label6 = new Label();
        label6.setText("Amount Paid");
        container.add(label6);
        label6.setBounds(10, 140, 80, 20);
        label7 = new Label();
        label7.setText("Sale Price");
        container.add(label7);
        label7.setBounds(10, 110, 60, 20);
        pack();
    /** The method registerEventHandlers() sets what each GUI object does.*/
    private void registerCompEventHandlers()
      ActionListener al = new ActionListener(){
            DateFormat fmt = DateFormat.getTimeInstance(DateFormat.SHORT);
            public void actionPerformed(ActionEvent evt) {
                jTextField2.setText(fmt.format(new Date()));
        new javax.swing.Timer(1000, al).start();
        getContentPane().add(jTextField2);
        SwingUtilities.invokeLater(new Runnable(){
            public void run() {
      /** Sets program to call method exitForm() when window is closed.*/
      addWindowListener( new WindowAdapter()
                           public void windowClosing(WindowEvent evt)
                             try {
                               saveFile();
                               System.exit(0);
                             catch ( IOException ioException )
      /** Tells what to do when an item is selected on the drop down menu.*/
      final ItemListener choiceListener;
      choice1.addItemListener(
       choiceListener = new ItemListener()
         public void itemStateChanged( ItemEvent event )
           boolean itemNotExist = true;
           for ( int i = 0; i < saleItems.size(); i++ )
             if ( choice1.getSelectedItem() == (String)saleItems.get( i ) )
               itemNotExist = false;
               jList1.setSelectedIndex( i );
               jTextField4.setText( (String)saleItemsQty.get( i ) );
           if ( itemNotExist == true )
             jTextField4.setText( "" );
           jButton1.setEnabled( itemNotExist );
           jButton7.setEnabled( false );
      /** When an item is selected, the items information is
       * displayed in the corresponding text field.*/
      jList1.addListSelectionListener(
       new ListSelectionListener()
         public void valueChanged( ListSelectionEvent event )
          if ( event.getSource() == jList1 && !event.getValueIsAdjusting() )
           int selection = 0;
           String selectionQty;
           try {
             for ( int i = 0; i < choice1.getItemCount(); i++ )
               if ( choice1.getItem(i) == jList1.getSelectedValue() )
                 selection = i;
             selectionQty = (String)saleItemsQty.get( jList1.getSelectedIndex() );
             choice1.select( selection );
           catch ( ArrayIndexOutOfBoundsException aoobException )
            selectionQty = "";
           jTextField4.setText( selectionQty );
           jButton1.setEnabled( false );
           jButton2.setEnabled( true );
           jButton3.setEnabled( true );
           jButton4.setEnabled( true );
           jButton7.setEnabled( false );
      /** Listens to jTextField and detects changes. */
      jText1.addDocumentListener(
        new DocumentListener()
          public void changedUpdate(DocumentEvent e)
            if ( saleItems.size() > 0 )
              for ( int i = 0; i < saleItems.size(); i++ )
                if ( choice1.getSelectedItem() == (String)saleItems.get( i ) )
                  jButton1.setEnabled( false );
                  if ( jTextField4.getText() != saleItemsQty.get( i ) )
                    jButton7.setEnabled( true );
                  else
                    jButton7.setEnabled( false );
            else
              jButton1.setEnabled( true );
              jButton7.setEnabled( false );
          public void insertUpdate(DocumentEvent e)
            if ( saleItems.size() > 0 )
              for ( int i = 0; i < saleItems.size(); i++ )
                if ( choice1.getSelectedItem() == (String)saleItems.get( i ) )
                  jButton1.setEnabled( false );
                  if ( jTextField4.getText() != saleItemsQty.get( i ) )
                    jButton7.setEnabled( true );
                  else
                    jButton7.setEnabled( false );
            else
              jButton1.setEnabled( true );
              jButton7.setEnabled( false );
          public void removeUpdate(DocumentEvent e)
            if ( saleItems.size() > 0 )
              for ( int i = 0; i < saleItems.size(); i++ )
                if ( choice1.getSelectedItem() == (String)saleItems.get( i ) )
                  jButton1.setEnabled( false );
                  if ( jTextField4.getText() != saleItemsQty.get( i ) )
                    jButton7.setEnabled( true );
                  else
                    jButton7.setEnabled( false );
            else
              jButton1.setEnabled( true );
              jButton7.setEnabled( false );
      /** When "Add Item" button is clicked, a new element
       *  is added to each vector.*/
      jButton1.addActionListener(
       new ActionListener()
         public void actionPerformed( ActionEvent event )
           String quantity = jTextField4.getText();
           jTextField4.setText( "" );
            try{
             for ( int i = 0; i < id.size(); i++ )
              if ( (String)id.get(i) == choice1.getSelectedItem() )
                salePrice += ( Double.parseDouble( (String)price.get(i) ) * Double.parseDouble( quantity ) );
             String newPrice = "$" + salePrice;
             saleItems.add( choice1.getSelectedItem() );
             saleItemsQty.add( quantity );
             jList1.setListData( saleItems );
             jScrollPane2.revalidate();
             jScrollPane2.repaint();
             jTextField6.setText( newPrice );
             jButton1.setEnabled( false );
            catch ( NumberFormatException num )
              JOptionPane.showMessageDialog( null, "Please enter a valid quantity!", "Error", JOptionPane.ERROR_MESSAGE );
            jList1.setSelectedIndex( saleItems.size() - 1 );
      /** When "Remove" button is clicked, the selected item is removed
       * from all vectors.*/
      jButton2.addActionListener(
       new ActionListener()
         public void actionPerformed( ActionEvent event )
           try {
           int selection = jList1.getSelectedIndex();
             for ( int i = 0; i < id.size(); i++ )
              if ( (String)id.get(i) == choice1.getSelectedItem() )
               salePrice -= ( Double.parseDouble( (String)price.get(i) ) * Double.parseDouble( (String)saleItemsQty.get( selection )  ) );
             String newPrice = "$" + salePrice;
             saleItems.removeElementAt( selection );
             saleItemsQty.removeElementAt( selection );
             jList1.setListData( saleItems );
             jScrollPane2.revalidate();
             jScrollPane2.repaint();
             jTextField6.setText( newPrice );
             if( selection >= id.size() )
              selection = id.size() - 1;
             jList1.setSelectedIndex( selection );
           catch ( ArrayIndexOutOfBoundsException exception )
             JOptionPane.showMessageDialog( null, "Please select an item to remove!", "Error", JOptionPane.ERROR_MESSAGE );
           if ( saleItems.size() == 0 )
             jButton2.setEnabled( false );
           else
             jButton2.setEnabled( true );
      /** When "Set Qty" button is clicked, the quantity of
       * the selected item is changed to the integer in
       * the qty text field.*/
      jButton7.addActionListener(
       new ActionListener()
         public void actionPerformed( ActionEvent event )
           int selection = jList1.getSelectedIndex();
           String newQty = jTextField4.getText();
           try {
             int numbertest = Integer.parseInt( newQty );
             for ( int i = 0; i < id.size(); i++ )
              if ( (String)id.get(i) == choice1.getSelectedItem() )
               salePrice -= ( Double.parseDouble( (String)price.get(i) ) * Double.parseDouble( (String)saleItemsQty.get( selection )  ) );
               salePrice += ( Double.parseDouble( (String)price.get(i) ) * Double.parseDouble( newQty ) );
             String newPrice = "$" + salePrice;
             saleItems.set( selection, choice1.getSelectedItem() );
             saleItemsQty.set( selection, newQty );
             jScrollPane2.revalidate();
             jScrollPane2.repaint();
             jTextField6.setText( newPrice );
             jButton7.setEnabled( false );
           catch ( NumberFormatException badinput )
             JOptionPane.showMessageDialog( null, "Please enter an integer!", "Error", JOptionPane.ERROR_MESSAGE );
      /** When "Print Reciept" button is clicked, the price of
       * the selected item is changed to the double in
       * the price text field.*/
      jButton3.addActionListener(
       new ActionListener()
         public void actionPerformed( ActionEvent event )
           try{
           String reciept = "\tStore Name";
           String items = "";
           String temp = jTextField5.getText();
           String amountPaidString = "";
           double amountPaid = 0.0;
           double change;
           for ( int i = 1; i < temp.length(); i++ )
             char a = temp.charAt(0);
             char b = temp.charAt(i);
             if ( a == '$' )
               amountPaidString += b;
             else
               amountPaidString = "Error";
           amountPaid = Double.parseDouble( amountPaidString );
           if (amountPaid >= salePrice)
           change = amountPaid - salePrice;
           reciept += "\nDate: " + jTextField3.getText()
             + "\t\tTime: " + jTextField2.getText()
             + "\nCashier: " + jTextField1.getText()
             + "\n\n\tItems:";
           for ( int i = 0; i < saleItems.size(); i++ )
             items += "\n" + saleItems.get( i ) + "\t\t$";
             for ( int h = 0; h < id.size(); h++ )
              if ( (String)id.get(h) == (String)saleItems.get( i ) )
                items += ( Double.parseDouble( (String)price.get(h) ) * Double.parseDouble( (String)saleItemsQty.get(h) ) );
           reciept += items + "\n\nTOTAL:\t$" + salePrice
             + "\nAmount Paid:\t$" + amountPaid
             + "\nChange:\t$" + change; 
             jTextArea1.setText( reciept );
             jScrollPane1.getViewport().add( jTextArea1 );
             jScrollPane1.revalidate();
             jScrollPane1.repaint();
             jButton1.setEnabled( false );
             jButton2.setEnabled( false );
             jButton3.setEnabled( false );
             jButton7.setEnabled( false );
             jTextField4.setEditable( false );
             jTextField5.setEditable( false );
             choice1.removeItemListener( choiceListener );
           else
             JOptionPane.showMessageDialog( null, "Amount Paid is not enough!", "Error", JOptionPane.ERROR_MESSAGE );
           catch ( NumberFormatException badinput )
             JOptionPane.showMessageDialog( null, "Please enter a valid amount paid!", "Error", JOptionPane.ERROR_MESSAGE );
      jButton4.addActionListener(
       new ActionListener()
         public void actionPerformed( ActionEvent event )
           int select = 3;
           select = JOptionPane.showConfirmDialog( null, "Are you sure you want quit this sale?" );
           if (select == 0)
             String[] run = {"xxx","yyy"};
             window.hide();
             main( run );
      jButton5.addActionListener(
       new ActionListener()
         public void actionPerformed( ActionEvent event )
           /* Code for what to do when "Change Cashier" button is clicked*/ /*
      jButton6.addActionListener(
       new ActionListener()
         public void actionPerformed( ActionEvent event )
           Inventory inventory = new Inventory();
           try{
           saveFile();
           catch ( IOException e )
           window.hide();
           inventory.runInventory();
           window = null;
    private void makeChoiceMenu()
      for ( int i = 0; i < id.size(); i++ )
        choice1.add( (String)id.get( i ) );
    /** The main method.*/
    public static void runComputer()
        window = new Computer();
        window.setSize(555, 335);
        window.show();
}This is the inventory class. It's used to make and edit the items in the inventory and then save them into the inventory file.
/** Java core packages*/
import java.util.*;
import java.text.*;
import java.awt.*;
import java.awt.event.*;
/** Java extension packages*/
import javax.swing.*;
import javax.swing.text.*;
import javax.swing.event.*;
import java.io.*;
/** This program displays the inventory of a store and
* allows user to edit each items name, quantity, and
* price. It opens and saves into a file "inventory.dat".
* @author Davin Green
public class Inventory extends LogIn
    private static Inventory window;
    /** Default constructor.*/
    public Inventory()
      super("Inventory Editor");
      try{
        try{
        openFile();
        createInvGUI();
        registerInvEventHandlers();
        catch ( IOException e )
      catch ( ClassNotFoundException e )
    /** The createGUI() methods creates and displays GUI components in the JFrame.*/
    private void createInvGUI() throws IOException
        /** Get JFrames content pane and set layout to null.*/
        Container container = getContentPane();
        container.setLayout(null);
        /** List of items displayed in scrolling pane.*/
        jList1 = new JList( id );
        /** Put JList into the scrolling pane, add scrolling pane
         * to content pane, and set position and size.*/
        jScrollPane1 = new JScrollPane();
        jScrollPane1.getViewport().add( jList1 );
        container.add(jScrollPane1);
        jScrollPane1.setBounds(0, 0, 210, 370);
        /** Button for adding a new item.*/
        jButton1 = new JButton();
        jButton1.setText("Add Item");
        container.add(jButton1);
        jButton1.setBounds(240, 10, 90, 30);
        /** Button for deleting a selected item.*/
        jButton2 = new JButton();
        jButton2.setText("Delete");
        container.add(jButton2);
        jButton2.setBounds(290, 50, 90, 30);
        /** Button for setting the quantity of an item.*/
        jButton3 = new JButton();
        jButton3.setText("Set Qty");
        container.add(jButton3);
        jButton3.setBounds(240, 100, 90, 30);
        /** Button for setting the price of an item.*/
        jButton4 = new JButton();
        jButton4.setText("Set Price");
        container.add(jButton4);
        jButton4.setBounds(240, 150, 90, 30);
        /** Text field for inputing and displaying the id (name) of an item.*/
        jTextField1 = new JTextField();
        container.add(jTextField1);
        jTextField1.setBounds(340, 10, 93, 30);
        jText1 = jTextField1.getDocument();
        /** Text field for inputing and displaying the quantity of an item.*/
        jTextField2 = new JTextField();
        container.add(jTextField2);
        jTextField2.setBounds(370, 100, 43, 30);
        jText2 = jTextField2.getDocument();
        /** Text field for inputing and displaying the price of an item.*/
        jTextField3 = new JTextField();
        container.add(jTextField3);
        jTextField3.setBounds(370, 150, 43, 30);
        jText3 = jTextField3.getDocument();
        /** Displays "Qty" before the quantity text field.*/
        label1 = new Label();
        label1.setText("Qty");
        container.add(label1);
        label1.setBounds(350, 100, 20, 20);
        /** Displays "Price" before the price text field.*/
        label2 = new Label();
        label2.setText("Price");
        container.add(label2);
        label2.setBounds(340, 150, 30, 20);
        /** Button to change cashier (return to cashier log-in panel).*/
        jButton5 = new JButton();
        jButton5.setText("Change Cashier");
        container.add(jButton5);
        jButton5.setBounds(260, 270, 130, 30);
        /** Button to make sell (open make sell panel).*/
        jButton6 = new JButton();
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                

Answer 1

/** JTextField objects for the text fields that are used in these programs.*/
public JTextField jTextField1, jTextField2, jTextField3,
                jTextField4, jTextField5, jTextField6;Your variable names don't mean anything.
So the person who has to maintain this program when you leave has a difficult task.
If there was some indication that the operator would key in (say) a quantity, that would
make it easier. You might name it "quantityText" in that case, or something like that.