Why am I getting a NullPointerException in my code?
I really need help...
Here is my code

I keep getting a Null Pointer Exception each time I try to run it using another class btw.
Here is the "another class":

Can some please read through it somehow without running it, because you would have to need the pictures...I just need to know if I did anything wrong, which I probably did since it is giving me this exception...

I really need help I don't know what to do, I've tried many things.

    import javax.swing.JFrame;
    
    public class BurgerMaker {
      
      public static void main(String[] args) { 
        
        JFrame frame = new JFrame ("Burger Maker");
        frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
          
        frame.getContentPane().add(new BurgerMakerPanel());
    
        frame.pack();
  

          frame.setVisible(true);
          }
    
      
    }



    import java.awt.*;
    import java.awt.event.*;
    import javax.swing.*;
    
    public class BurgerMakerPanel extends JPanel{
      private final int WIDTH = 600, HEIGHT = 1200;
      private JLabel inputLabel, inputLabel2, inputLabel3, inputLabel4, inputLabel5, inputLabel6, inputLabel7, titleLabel, titleLabel2, topBreadPicture, bottomBreadPicture, 
        pattyPicture, cheesePicture, veggiePicture, saucePicture;
      private JComboBox breadList, breadList2, pattyList, vegetableList, sauceList, cheeseList;
      private JPanel primary, picturePanel, test, test2, test3, test4, titlePanel, spacePanel, topBreadPanel, bottomBreadPanel, pattyPanel, veggiePanel, saucePanel, cheesePanel;
      private JButton push;
    
      public BurgerMakerPanel() { 
        String[] breadStrings = {"White Bread Top", "Rye Bread Top", "Hamburger Bread Top", "Wheat Bread Top"};
        String[] pattyStrings = {"Beef", "Chicken", "Pork"};
        String[] veggieStrings = {"Lettuce", "Tomato", "Pickle", "Onion"};
        String[] bread2Strings = {"White Bread Bottom", "Rye Bread Bottom", "Hamburger Bread Bottom", "Wheat Bread Bottom"};
        String[] cheeseStrings = {"American", "Swiss Cheese", "Cheddar Cheese", "Pepper Jack Cheese"};
        String[] sauceStrings = {"Mayonnaise", "Mustard", "Ketchup", "BBQ"};
        
        push = new JButton("Create my Sandwich/Burger!");
        
        TopBreadListener tbl = new TopBreadListener();
        BottomBreadListener bbl = new BottomBreadListener();
        PattyListener pl = new PattyListener();
        CheeseListener cl = new CheeseListener();
        SauceListener sl = new SauceListener();
        VeggieListener vl = new VeggieListener();
        
        JLabel separatorLabel = new JLabel("  ________________________________________________________________  " );
        separatorLabel.setFont(new Font("Courier New", Font.BOLD, 14));
        
        JLabel separatorLabel2 = new JLabel("  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  " );
        separatorLabel2.setFont(new Font("Courier New", Font.BOLD, 14));
        
        inputLabel = new JLabel("Select your type of bottom bread:", SwingConstants.CENTER);
        inputLabel.setFont(new Font("Verdana", Font.PLAIN, 14));
        breadList = new JComboBox(breadStrings);
        breadList.setSelectedIndex(3);
        breadList.addActionListener(new TopBreadListener());
        tbl.updateLabel(breadStrings[breadList.getSelectedIndex()]);
        
        
        inputLabel2 = new JLabel("Select your type of patty:", SwingConstants.CENTER);
        inputLabel2.setFont(new Font("Verdana", Font.PLAIN, 14));
        pattyList = new JComboBox(pattyStrings);
        pattyList.setSelectedIndex(2);
        pattyList.addActionListener(new PattyListener());
        pl.updateLabel(pattyStrings[pattyList.getSelectedIndex()]);
        
        inputLabel3 = new JLabel("Select your type of sauce:", SwingConstants.CENTER);
        inputLabel3.setFont(new Font("Verdana", Font.PLAIN, 14));
        sauceList = new JComboBox(sauceStrings);
        sauceList.setSelectedIndex(3);
        sauceList.addActionListener(new SauceListener());
        sl.updateLabel(sauceStrings[sauceList.getSelectedIndex()]);
        
        inputLabel4 = new JLabel("Select your type of cheese:", SwingConstants.CENTER);
        inputLabel4.setFont(new Font("Verdana", Font.PLAIN, 14));
        cheeseList = new JComboBox(cheeseStrings);
        cheeseList.setSelectedIndex(3);
        cheeseList.addActionListener(new CheeseListener());
        cl.updateLabel(cheeseStrings[cheeseList.getSelectedIndex()]);
        
        inputLabel5 = new JLabel("Select your type of vegetable:", SwingConstants.CENTER);
        inputLabel5.setFont(new Font("Verdana", Font.PLAIN, 14));
        vegetableList = new JComboBox(veggieStrings);
        vegetableList.setSelectedIndex(3);
        vegetableList.addActionListener(new VeggieListener());
        vl.updateLabel(veggieStrings[vegetableList.getSelectedIndex()]);
        
        inputLabel6 = new JLabel("Select your type of top bread:", SwingConstants.CENTER);
        inputLabel6.setFont(new Font("Verdana", Font.PLAIN, 14));
        breadList2 = new JComboBox(bread2Strings);
        breadList2.setSelectedIndex(4);
        breadList2.addActionListener(new BottomBreadListener());
        bbl.updateLabel(bread2Strings[breadList2.getSelectedIndex()]);
        
        inputLabel7 = new JLabel("Press this only when you are done making your sandwich/burger!", SwingConstants.CENTER);
        inputLabel7.setFont(new Font("Verdana", Font.BOLD, 14));
        
        titleLabel = new JLabel("This is a program that will help you make your own sandwich or burger!", SwingConstants.CENTER);
        titleLabel2 = new JLabel("Follow all directions and have fun! Thank you!", SwingConstants.CENTER);
        titleLabel.setFont(new Font("Verdana", Font.BOLD, 15));
        titleLabel2.setFont(new Font("Verdana", Font.BOLD, 15));
        
        primary = new JPanel();
        // Set up first subpanel
        picturePanel = new JPanel();
        spacePanel = new JPanel();
        titlePanel = new JPanel();
        
        topBreadPanel = new JPanel();
        saucePanel = new JPanel();
        pattyPanel = new JPanel();
        cheesePanel = new JPanel();
        veggiePanel = new JPanel();
        bottomBreadPanel = new JPanel();
        topBreadPanel.setPreferredSize(new Dimension(600, 70));
        saucePanel.setPreferredSize(new Dimension(600, 7));
        pattyPanel.setPreferredSize(new Dimension(600, 127));
        cheesePanel.setPreferredSize(new Dimension(600, 9));
        veggiePanel.setPreferredSize(new Dimension(600, 58));
        bottomBreadPanel.setPreferredSize(new Dimension(600, 70));
        
        test = new JPanel();
        test2 = new JPanel();
        test3 = new JPanel();
        test4 = new JPanel();
        titlePanel.setPreferredSize(new Dimension(600, 60));
        spacePanel.setPreferredSize(new Dimension(600, 5));
        test.setPreferredSize(new Dimension(500, 80));
        test2.setPreferredSize(new Dimension(450, 80));
        test3.setPreferredSize(new Dimension(450, 80));
        test4.setPreferredSize(new Dimension(600, 60));
        picturePanel.setPreferredSize(new Dimension(600, 600));
        JLabel label1 = new JLabel ("Here is your finished product!");
       
        picturePanel.add(label1);
        picturePanel.add(topBreadPanel);
        picturePanel.add(saucePanel);
        picturePanel.add(pattyPanel);
        picturePanel.add(cheesePanel);
        picturePanel.add(veggiePanel);
        picturePanel.add(bottomBreadPanel);
        
        titlePanel.add(titleLabel);
        titlePanel.add(titleLabel2);
        
        test.add(inputLabel);
        test.add(breadList); 
        
        test.add(inputLabel6);
        test.add(breadList2); 
        
        test2.add(inputLabel2);
        test2.add(pattyList); 
        
        test2.add(inputLabel4);
        test2.add(cheeseList);
        
        test3.add(inputLabel5);
        test3.add(vegetableList);
        
        test3.add(inputLabel3);
        test3.add(sauceList);
        
        test4.add(inputLabel7);
        test4.add(push);
        
        primary.add(spacePanel);
        primary.add(titlePanel);
        primary.add(separatorLabel2);
        primary.add(test);
        primary.add(test2);
        primary.add(test3);
        primary.add(test4);
        primary.add(separatorLabel);
        primary.add(spacePanel);
        primary.add(picturePanel);
        
        primary.setPreferredSize(new Dimension(WIDTH, HEIGHT));
      }
      public JPanel getPanel(){
          return primary;
        }
      private class TopBreadListener implements ActionListener{
        public void actionPerformed(ActionEvent e){
          JComboBox ceb1 = (JComboBox)e.getSource();
          String ingredientName1 = (String)ceb1.getSelectedItem();
          updateLabel(ingredientName1);
        }
        public void updateLabel(String name) {
          ImageIcon icon1 = new ImageIcon(name + ".png");
          topBreadPicture.setIcon(icon1);
        }
      }  
      private class BottomBreadListener implements ActionListener{
        public void actionPerformed(ActionEvent e){
          JComboBox ceb2 = (JComboBox)e.getSource();
          String ingredientName2 = (String)ceb2.getSelectedItem();
          updateLabel(ingredientName2);
        }
        public void updateLabel(String name) {
          ImageIcon icon2 = new ImageIcon(name + ".png");
          bottomBreadPicture.setIcon(icon2);
        }
      }  
      private class PattyListener implements ActionListener{
        public void actionPerformed(ActionEvent e){
          JComboBox ceb3 = (JComboBox)e.getSource();
          String ingredientName3 = (String)ceb3.getSelectedItem();
          updateLabel(ingredientName3);
        }
        public void updateLabel(String name) {
          ImageIcon icon3 = new ImageIcon(name + ".png");
          pattyPicture.setIcon(icon3);
        }
      }  
      private class CheeseListener implements ActionListener{
        public void actionPerformed(ActionEvent e){
          JComboBox ceb4 = (JComboBox)e.getSource();
          String ingredientName4 = (String)ceb4.getSelectedItem();
          updateLabel(ingredientName4);
        }
        public void updateLabel(String name) {
          ImageIcon icon4 = new ImageIcon(name + ".png");
          cheesePicture.setIcon(icon4);
        }
      }  
      private class VeggieListener implements ActionListener{
        public void actionPerformed(ActionEvent e){
          JComboBox ceb5 = (JComboBox)e.getSource();
          String ingredientName5 = (String)ceb5.getSelectedItem();
          updateLabel(ingredientName5);
        }
        public void updateLabel(String name) {
          ImageIcon icon5 = new ImageIcon(name + ".png");
          veggiePicture.setIcon(icon5);
        }
      }
      private class SauceListener implements ActionListener{
        public void actionPerformed(ActionEvent e){
          JComboBox ceb6 = (JComboBox)e.getSource();
          String ingredientName6 = (String)ceb6.getSelectedItem();
          updateLabel(ingredientName6);
        }
        public void updateLabel(String name) {
          ImageIcon icon6 = new ImageIcon(name + ".png");
          saucePicture.setIcon(icon6);
        }
      }  
    }
      


Why am I getting a NullPointerException in my code?
===

I really need help...
Here is my code

I keep getting a Null Pointer Exception each time I try to run it using another class btw.
Here is the "another class":

Can some please read through it somehow without running it, because you would have to need the pictures...I just need to know if I did anything wrong, which I probably did since it is giving me this exception...

I really need help I don't know what to do, I've tried many things.

    import javax.swing.JFrame;
    
    public class BurgerMaker {
      
      public static void main(String[] args) { 
        
        JFrame frame = new JFrame ("Burger Maker");
        frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
          
        frame.getContentPane().add(new BurgerMakerPanel());
    
        frame.pack();
  

          frame.setVisible(true);
          }
    
      
    }



    import java.awt.*;
    import java.awt.event.*;
    import javax.swing.*;
    
    public class BurgerMakerPanel extends JPanel{
      private final int WIDTH = 600, HEIGHT = 1200;
      private JLabel inputLabel, inputLabel2, inputLabel3, inputLabel4, inputLabel5, inputLabel6, inputLabel7, titleLabel, titleLabel2, topBreadPicture, bottomBreadPicture, 
        pattyPicture, cheesePicture, veggiePicture, saucePicture;
      private JComboBox breadList, breadList2, pattyList, vegetableList, sauceList, cheeseList;
      private JPanel primary, picturePanel, test, test2, test3, test4, titlePanel, spacePanel, topBreadPanel, bottomBreadPanel, pattyPanel, veggiePanel, saucePanel, cheesePanel;
      private JButton push;
    
      public BurgerMakerPanel() { 
        String[] breadStrings = {"White Bread Top", "Rye Bread Top", "Hamburger Bread Top", "Wheat Bread Top"};
        String[] pattyStrings = {"Beef", "Chicken", "Pork"};
        String[] veggieStrings = {"Lettuce", "Tomato", "Pickle", "Onion"};
        String[] bread2Strings = {"White Bread Bottom", "Rye Bread Bottom", "Hamburger Bread Bottom", "Wheat Bread Bottom"};
        String[] cheeseStrings = {"American", "Swiss Cheese", "Cheddar Cheese", "Pepper Jack Cheese"};
        String[] sauceStrings = {"Mayonnaise", "Mustard", "Ketchup", "BBQ"};
        
        push = new JButton("Create my Sandwich/Burger!");
        
        TopBreadListener tbl = new TopBreadListener();
        BottomBreadListener bbl = new BottomBreadListener();
        PattyListener pl = new PattyListener();
        CheeseListener cl = new CheeseListener();
        SauceListener sl = new SauceListener();
        VeggieListener vl = new VeggieListener();
        
        JLabel separatorLabel = new JLabel("  ________________________________________________________________  " );
        separatorLabel.setFont(new Font("Courier New", Font.BOLD, 14));
        
        JLabel separatorLabel2 = new JLabel("  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  " );
        separatorLabel2.setFont(new Font("Courier New", Font.BOLD, 14));
        
        inputLabel = new JLabel("Select your type of bottom bread:", SwingConstants.CENTER);
        inputLabel.setFont(new Font("Verdana", Font.PLAIN, 14));
        breadList = new JComboBox(breadStrings);
        breadList.setSelectedIndex(3);
        breadList.addActionListener(new TopBreadListener());
        tbl.updateLabel(breadStrings[breadList.getSelectedIndex()]);
        
        
        inputLabel2 = new JLabel("Select your type of patty:", SwingConstants.CENTER);
        inputLabel2.setFont(new Font("Verdana", Font.PLAIN, 14));
        pattyList = new JComboBox(pattyStrings);
        pattyList.setSelectedIndex(2);
        pattyList.addActionListener(new PattyListener());
        pl.updateLabel(pattyStrings[pattyList.getSelectedIndex()]);
        
        inputLabel3 = new JLabel("Select your type of sauce:", SwingConstants.CENTER);
        inputLabel3.setFont(new Font("Verdana", Font.PLAIN, 14));
        sauceList = new JComboBox(sauceStrings);
        sauceList.setSelectedIndex(3);
        sauceList.addActionListener(new SauceListener());
        sl.updateLabel(sauceStrings[sauceList.getSelectedIndex()]);
        
        inputLabel4 = new JLabel("Select your type of cheese:", SwingConstants.CENTER);
        inputLabel4.setFont(new Font("Verdana", Font.PLAIN, 14));
        cheeseList = new JComboBox(cheeseStrings);
        cheeseList.setSelectedIndex(3);
        cheeseList.addActionListener(new CheeseListener());
        cl.updateLabel(cheeseStrings[cheeseList.getSelectedIndex()]);
        
        inputLabel5 = new JLabel("Select your type of vegetable:", SwingConstants.CENTER);
        inputLabel5.setFont(new Font("Verdana", Font.PLAIN, 14));
        vegetableList = new JComboBox(veggieStrings);
        vegetableList.setSelectedIndex(3);
        vegetableList.addActionListener(new VeggieListener());
        vl.updateLabel(veggieStrings[vegetableList.getSelectedIndex()]);
        
        inputLabel6 = new JLabel("Select your type of top bread:", SwingConstants.CENTER);
        inputLabel6.setFont(new Font("Verdana", Font.PLAIN, 14));
        breadList2 = new JComboBox(bread2Strings);
        breadList2.setSelectedIndex(4);
        breadList2.addActionListener(new BottomBreadListener());
        bbl.updateLabel(bread2Strings[breadList2.getSelectedIndex()]);
        
        inputLabel7 = new JLabel("Press this only when you are done making your sandwich/burger!", SwingConstants.CENTER);
        inputLabel7.setFont(new Font("Verdana", Font.BOLD, 14));
        
        titleLabel = new JLabel("This is a program that will help you make your own sandwich or burger!", SwingConstants.CENTER);
        titleLabel2 = new JLabel("Follow all directions and have fun! Thank you!", SwingConstants.CENTER);
        titleLabel.setFont(new Font("Verdana", Font.BOLD, 15));
        titleLabel2.setFont(new Font("Verdana", Font.BOLD, 15));
        
        primary = new JPanel();
        // Set up first subpanel
        picturePanel = new JPanel();
        spacePanel = new JPanel();
        titlePanel = new JPanel();
        
        topBreadPanel = new JPanel();
        saucePanel = new JPanel();
        pattyPanel = new JPanel();
        cheesePanel = new JPanel();
        veggiePanel = new JPanel();
        bottomBreadPanel = new JPanel();
        topBreadPanel.setPreferredSize(new Dimension(600, 70));
        saucePanel.setPreferredSize(new Dimension(600, 7));
        pattyPanel.setPreferredSize(new Dimension(600, 127));
        cheesePanel.setPreferredSize(new Dimension(600, 9));
        veggiePanel.setPreferredSize(new Dimension(600, 58));
        bottomBreadPanel.setPreferredSize(new Dimension(600, 70));
        
        test = new JPanel();
        test2 = new JPanel();
        test3 = new JPanel();
        test4 = new JPanel();
        titlePanel.setPreferredSize(new Dimension(600, 60));
        spacePanel.setPreferredSize(new Dimension(600, 5));
        test.setPreferredSize(new Dimension(500, 80));
        test2.setPreferredSize(new Dimension(450, 80));
        test3.setPreferredSize(new Dimension(450, 80));
        test4.setPreferredSize(new Dimension(600, 60));
        picturePanel.setPreferredSize(new Dimension(600, 600));
        JLabel label1 = new JLabel ("Here is your finished product!");
       
        picturePanel.add(label1);
        picturePanel.add(topBreadPanel);
        picturePanel.add(saucePanel);
        picturePanel.add(pattyPanel);
        picturePanel.add(cheesePanel);
        picturePanel.add(veggiePanel);
        picturePanel.add(bottomBreadPanel);
        
        titlePanel.add(titleLabel);
        titlePanel.add(titleLabel2);
        
        test.add(inputLabel);
        test.add(breadList); 
        
        test.add(inputLabel6);
        test.add(breadList2); 
        
        test2.add(inputLabel2);
        test2.add(pattyList); 
        
        test2.add(inputLabel4);
        test2.add(cheeseList);
        
        test3.add(inputLabel5);
        test3.add(vegetableList);
        
        test3.add(inputLabel3);
        test3.add(sauceList);
        
        test4.add(inputLabel7);
        test4.add(push);
        
        primary.add(spacePanel);
        primary.add(titlePanel);
        primary.add(separatorLabel2);
        primary.add(test);
        primary.add(test2);
        primary.add(test3);
        primary.add(test4);
        primary.add(separatorLabel);
        primary.add(spacePanel);
        primary.add(picturePanel);
        
        primary.setPreferredSize(new Dimension(WIDTH, HEIGHT));
      }
      public JPanel getPanel(){
          return primary;
        }
      private class TopBreadListener implements ActionListener{
        public void actionPerformed(ActionEvent e){
          JComboBox ceb1 = (JComboBox)e.getSource();
          String ingredientName1 = (String)ceb1.getSelectedItem();
          updateLabel(ingredientName1);
        }
        public void updateLabel(String name) {
          ImageIcon icon1 = new ImageIcon(name + ".png");
          topBreadPicture.setIcon(icon1);
        }
      }  
      private class BottomBreadListener implements ActionListener{
        public void actionPerformed(ActionEvent e){
          JComboBox ceb2 = (JComboBox)e.getSource();
          String ingredientName2 = (String)ceb2.getSelectedItem();
          updateLabel(ingredientName2);
        }
        public void updateLabel(String name) {
          ImageIcon icon2 = new ImageIcon(name + ".png");
          bottomBreadPicture.setIcon(icon2);
        }
      }  
      private class PattyListener implements ActionListener{
        public void actionPerformed(ActionEvent e){
          JComboBox ceb3 = (JComboBox)e.getSource();
          String ingredientName3 = (String)ceb3.getSelectedItem();
          updateLabel(ingredientName3);
        }
        public void updateLabel(String name) {
          ImageIcon icon3 = new ImageIcon(name + ".png");
          pattyPicture.setIcon(icon3);
        }
      }  
      private class CheeseListener implements ActionListener{
        public void actionPerformed(ActionEvent e){
          JComboBox ceb4 = (JComboBox)e.getSource();
          String ingredientName4 = (String)ceb4.getSelectedItem();
          updateLabel(ingredientName4);
        }
        public void updateLabel(String name) {
          ImageIcon icon4 = new ImageIcon(name + ".png");
          cheesePicture.setIcon(icon4);
        }
      }  
      private class VeggieListener implements ActionListener{
        public void actionPerformed(ActionEvent e){
          JComboBox ceb5 = (JComboBox)e.getSource();
          String ingredientName5 = (String)ceb5.getSelectedItem();
          updateLabel(ingredientName5);
        }
        public void updateLabel(String name) {
          ImageIcon icon5 = new ImageIcon(name + ".png");
          veggiePicture.setIcon(icon5);
        }
      }
      private class SauceListener implements ActionListener{
        public void actionPerformed(ActionEvent e){
          JComboBox ceb6 = (JComboBox)e.getSource();
          String ingredientName6 = (String)ceb6.getSelectedItem();
          updateLabel(ingredientName6);
        }
        public void updateLabel(String name) {
          ImageIcon icon6 = new ImageIcon(name + ".png");
          saucePicture.setIcon(icon6);
        }
      }  
    }
      

