Strange run-time error in Java [duplicate]

I have a simple program that takes in some information about purchased items and adds the total cost. I am getting some errors during runtime, which I think have something to do with the way in which I created the buttons.

 import javax.swing.*; import java.awt.*; import java.awt.event.*; /* Day 3 - Lab 1 */ public class Orders extends JFrame implements ActionListener { private JTextField itemName; private JTextField numberOf; private JTextField cost; private JTextField amountOwed; private JButton jbCalc; private JButton jbSave; private JButton jbClear; private JButton jbExit; // Main class public static void main(String [] args) { Orders create = new Orders(); } // Constructor public Orders() { //Content panel JPanel content = new JPanel(new GridLayout(4,2) ); //Add labels and text fields to that panel content.add( new JLabel("Item Name:") ); JTextField itemName = new JTextField(5); content.add( itemName ); content.add( new JLabel("Number of:") ); JTextField numberOf = new JTextField(5); content.add( numberOf ); content.add( new JLabel("Cost:") ); JTextField cost = new JTextField(5); content.add( cost ); content.add( new JLabel("Amount owed:") ); JTextField amountOwed = new JTextField(5); content.add( amountOwed ); amountOwed.setEnabled(false); add( content, BorderLayout.CENTER); //Control panel JPanel control = new JPanel(); // Add the buttons jbCalc = new JButton("Calculate"); control.add( jbCalc ); jbCalc.addActionListener( this ); // button - Save jbSave = new JButton("Save"); control.add( jbSave ); jbSave.addActionListener( this ); // button - Clear jbClear = new JButton("Clear"); control.add( jbClear ); jbClear.addActionListener( this ); // button - Exit jbExit = new JButton("Exit"); control.add( jbExit ); jbExit.addActionListener( this ); add( control, BorderLayout.SOUTH ); // Show it pack(); setLocationRelativeTo(null); setVisible(true); } // Actions of Buttons @Override public void actionPerformed(ActionEvent a) { Object choice = a.getSource(); // Button - Calculate if ( choice == jbCalc ) { System.out.println("Calculating..."); String test = itemName.getText(); } // Button - Save else if ( choice == jbSave ) { System.out.println("Saving..."); } // Button - Clear else if ( choice == jbClear ) { System.out.println("Clearing..."); itemName.setText(""); numberOf.setText(null); cost.setText(null); amountOwed.setText(null); } // Button - Exit else if ( choice == jbExit ) { System.out.println("Exiting..."); System.exit(0); } } } 

And here are the error messages:

Clearing... Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at Orders.actionPerformed(Orders.java:107) at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022) at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348) at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402) at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259) at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252) at java.awt.Component.processMouseEvent(Component.java:6533) at javax.swing.JComponent.processMouseEvent(JComponent.java:3324) at java.awt.Component.processEvent(Component.java:6298) at java.awt.Container.processEvent(Container.java:2236) at java.awt.Component.dispatchEventImpl(Component.java:4889) at java.awt.Container.dispatchEventImpl(Container.java:2294) at java.awt.Component.dispatchEvent(Component.java:4711) at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4888) at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4525) at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4466) at java.awt.Container.dispatchEventImpl(Container.java:2280) at java.awt.Window.dispatchEventImpl(Window.java:2746) at java.awt.Component.dispatchEvent(Component.java:4711) at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758) at java.awt.EventQueue.access$500(EventQueue.java:97) at java.awt.EventQueue$3.run(EventQueue.java:709) at java.awt.EventQueue$3.run(EventQueue.java:703) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76) at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86) at java.awt.EventQueue$4.run(EventQueue.java:731) at java.awt.EventQueue$4.run(EventQueue.java:729) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76) at java.awt.EventQueue.dispatchEvent(EventQueue.java:728) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93) at java.awt.EventDispatchThread.run(EventDispatchThread.java:82) Saving... Exiting... 

Not sure what to make of that ^ so any help is appreciated. Thanks!