Why do I get the following exception when I press the cancel buuton?

Question

My code is not complete as I am stubbing my code. Can someone tell me why i get the following exception
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
        at Phonebook.createNew(Phonebook.java:244)
        at Phonebook.actionPerformed(Phonebook.java:222)
        at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:19
95)
        at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.jav
a:2318)
        at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel
.java:387)
        at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242
        at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonL
istener.java:236)
        at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:2
72)
        at java.awt.Component.processMouseEvent(Component.java:6038)
        at javax.swing.JComponent.processMouseEvent(JComponent.java:3265)
        at java.awt.Component.processEvent(Component.java:5803)
        at java.awt.Container.processEvent(Container.java:2058)
        at java.awt.Component.dispatchEventImpl(Component.java:4410)
        at java.awt.Container.dispatchEventImpl(Container.java:2116)
        at java.awt.Component.dispatchEvent(Component.java:4240)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4322
        at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3986)
        at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3916)
        at java.awt.Container.dispatchEventImpl(Container.java:2102)
        at java.awt.Window.dispatchEventImpl(Window.java:2429)
        at java.awt.Component.dispatchEvent(Component.java:4240)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThre
ad.java:273)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.
java:183)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThre
ad.java:173)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)in the following code whenever I press the cancel button in the part of code that tests fro when a user clicks the create button.
     Filename:     ContactsListInterface.java
     Date:           16 March 2008
     Programmer:     Yucca Nel
     Purpose:     Provides a GUI for entering names and contact numbers into a telephone directory.
                    Also allows options for searching for a specific name and deleting of data from the record
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.*;
import java.io.*;
import java.util.*;
import java.text.*;
public class Phonebook extends JFrame implements ActionListener
{ //start of class
     // construct fields, buttons, labels,text boxes, ArrayLists etc
     JTextPane displayPane = new JTextPane();
     JLabel listOfContacts = new JLabel("List Of Contacts");               // creates a label for the scrollpane
     JButton createButton = new JButton("Create");
     JButton searchButton = new JButton("Search");
     JButton modifyButton = new JButton("Modify");
     JButton deleteButton = new JButton("Delete");
     ArrayList fNameList = new ArrayList();
     ArrayList sNameList = new ArrayList();
     ArrayList hList = new ArrayList();
     ArrayList wList = new ArrayList();
     ArrayList cList = new ArrayList();
     public String name, surname, home, work, cell;
     // create an instance of the ContactsListInterface
     public Phonebook()
     { // start of cli()
          super("Phonebook Interface");
     } // end of cli()
     public JMenuBar createMenuBar()
     { // start of the createMenuBar()
          // construct and populate a menu bar
          JMenuBar mnuBar = new JMenuBar();                    // creates a menu bar
          setJMenuBar(mnuBar);
          JMenu mnuFile = new JMenu("File",true);               // creates a file menu in the menu bar which is visible
               mnuFile.setMnemonic(KeyEvent.VK_F);
               mnuFile.setDisplayedMnemonicIndex(0);
               mnuFile.setToolTipText("File Options");
               mnuBar.add(mnuFile);
          JMenuItem mnuFileExit = new JMenuItem("Save And Exit");     // creates an exit option in the file menu
               mnuFileExit.setMnemonic(KeyEvent.VK_X);
               mnuFileExit.setDisplayedMnemonicIndex(1);
               mnuFileExit.setToolTipText("Close Application");
               mnuFile.add(mnuFileExit);
               mnuFileExit.setActionCommand("Exit");
               mnuFileExit.addActionListener(this);
          JMenu mnuEdit = new JMenu("Edit",true);               // creates a menu for editing options
               mnuEdit.setMnemonic(KeyEvent.VK_E);
               mnuEdit.setDisplayedMnemonicIndex(0);
               mnuEdit.setToolTipText("Edit Options");
               mnuBar.add(mnuEdit);
          JMenu mnuEditSort = new JMenu("Sort",true);          // creates an option for sorting entries
               mnuEditSort.setMnemonic(KeyEvent.VK_S);
               mnuEditSort.setDisplayedMnemonicIndex(0);
               mnuEdit.add(mnuEditSort);
          JMenuItem mnuEditSortByName = new JMenuItem("Sort By Name");          // to sort entries by name
               mnuEditSortByName.setMnemonic(KeyEvent.VK_N);
               mnuEditSortByName.setDisplayedMnemonicIndex(8);
               mnuEditSortByName.setToolTipText("Sort entries by first name");
               mnuEditSortByName.setActionCommand("Name");
               mnuEditSortByName.addActionListener(this);
               mnuEditSort.add(mnuEditSortByName);
          JMenuItem mnuEditSortBySurname = new JMenuItem("Sort By Surname");     // to sort entries by surname
               mnuEditSortBySurname.setMnemonic(KeyEvent.VK_R);
               mnuEditSortBySurname.setDisplayedMnemonicIndex(10);
               mnuEditSortBySurname.setToolTipText("Sort entries by surname");
               mnuEditSortBySurname.setActionCommand("Surname");
               mnuEditSortBySurname.addActionListener(this);
               mnuEditSort.add(mnuEditSortBySurname);
          JMenu mnuHelp = new JMenu("Help",true);                    // creates a menu for help options
               mnuHelp.setMnemonic(KeyEvent.VK_H);
               mnuHelp.setDisplayedMnemonicIndex(0);
               mnuHelp.setToolTipText("Help options");
               mnuBar.add(mnuHelp);
          JMenuItem mnuHelpHelp = new JMenuItem("Help");          // creates a help option for help topic
               mnuHelpHelp.setMnemonic(KeyEvent.VK_P);
               mnuHelpHelp.setDisplayedMnemonicIndex(3);
               mnuHelpHelp.setToolTipText("Help Topic");
               mnuHelpHelp.setActionCommand("Help");
               mnuHelpHelp.addActionListener(this);
               mnuHelp.add(mnuHelpHelp);
          JMenuItem mnuHelpAbout = new JMenuItem("About");     // creates a about option for info about api
               mnuHelpAbout.setMnemonic(KeyEvent.VK_T);
               mnuHelpAbout.setDisplayedMnemonicIndex(4);
               mnuHelpAbout.setToolTipText("About this program");
               mnuHelpAbout.setActionCommand("About");
               mnuHelpAbout.addActionListener(this);
               mnuHelp.add(mnuHelpAbout);
          return mnuBar;
     } // end of the createMenuBar()
     // create the content pane
     public Container createContentPane()
     { // start of createContentPane()
          //construct and populate panels and content pane
          JPanel labelPanel = new JPanel(); // panel is only used to put the label for the textpane in
               labelPanel.setLayout(new FlowLayout());
               labelPanel.add(listOfContacts);
          JPanel displayPanel = new JPanel();// panel is used to display all the contacts and thier numbers
               setTabsAndStyles(displayPane);
               displayPane = addTextToTextPane();
               displayPane.setEditable(false);
          JScrollPane scrollPane = new JScrollPane(displayPane);
               scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS); // pane is scrollable vertically
               scrollPane.setWheelScrollingEnabled(true);// pane is scrollable by use of the mouse wheel
               scrollPane.setPreferredSize(new Dimension(400,320));
          displayPanel.add(scrollPane);
          JPanel workPanel = new JPanel();// panel is used to enter, edit and delete data
               workPanel.setLayout(new FlowLayout());
               workPanel.add(createButton);
                    createButton.setToolTipText("Create a new entry");
                    createButton.addActionListener(this);
               workPanel.add(searchButton);
                    searchButton.setToolTipText("Search for an entry by name number or surname");
                    searchButton.addActionListener(this);
               workPanel.add(modifyButton);
                    modifyButton.setToolTipText("Modify an existing entry");
                    modifyButton.addActionListener(this);
               workPanel.add(deleteButton);
                    deleteButton.setToolTipText("Delete an existing entry");
                    deleteButton.addActionListener(this);
          labelPanel.setBackground(Color.red);
          displayPanel.setBackground(Color.red);
          workPanel.setBackground(Color.red);
          // create container and set attributes
          Container c = getContentPane();
               c.setLayout(new BorderLayout(30,30));
               c.add(labelPanel,BorderLayout.NORTH);
               c.add(displayPanel,BorderLayout.CENTER);
               c.add(workPanel,BorderLayout.SOUTH);
               c.setBackground(Color.red);
          // add a listener for the window closing and save
          addWindowListener(
               new WindowAdapter()
                    public void windowClosing(WindowEvent e)
                         int answer = JOptionPane.showConfirmDialog(null,"Are you sure you would like to save all changes and exit?","File submission",JOptionPane.YES_NO_OPTION);
                         if(answer == JOptionPane.YES_OPTION)
                              System.exit(0);
          return c;
     } // end of createContentPane()
     protected void setTabsAndStyles(JTextPane displayPane)
     { // Start of setTabsAndStyles()
          // set Font style
          Style fontStyle = StyleContext.getDefaultStyleContext().getStyle(StyleContext.DEFAULT_STYLE);
          Style regular = displayPane.addStyle("regular", fontStyle);
          StyleConstants.setFontFamily(fontStyle, "SansSerif");
          Style s = displayPane.addStyle("bold", regular);
          StyleConstants.setBold(s,true);
     } // End of setTabsAndStyles()
     public JTextPane addTextToTextPane()
     { // start of addTextToTextPane()
          Document doc = displayPane.getDocument();
          try
          { // start of tryblock
               // clear previous text
               doc.remove(0,doc.getLength());
               // insert titles of columns
               doc.insertString(0,"NAME\tSURNAME\tHOME NO\tWORK NO\tCELL NO\n",displayPane.getStyle("bold"));
          } // end of try block
          catch(BadLocationException ble)
          { // start of ble exception handler
               System.err.println("Could not insert text.");
          } // end of ble exception handler
          return displayPane;
     } // end of addTextToTextPane()
     // code to process user clicks
     public void actionPerformed(ActionEvent e)
     { // start of actionPerformed()
          String arg = e.getActionCommand();
          // user clicks create button
          if(arg.equals("Create"))
               createNew();
          if(arg.equals("Search"))
          if(arg.equals("Modify"))
          if(arg.equals("Delete"))
          if(arg.equals("Exit"))
     } // end of actionPerformed()
     // method to create a new contact
     public void createNew()
     { // start of create new contact()
          name = JOptionPane.showInputDialog(null,"Please enter the new contacts first name or press cancel to exit.");
          if(name == null)     finish();                         // if user clicks cancel
          if(name.length() <=0)
               JOptionPane.showMessageDialog(null,"You did not enter a valid name.\nPlease make sure you enter data correctly.","Error",JOptionPane.ERROR_MESSAGE);
               createNew();                                   // To return to the create method
          surname = JOptionPane.showInputDialog(null,"Please enter the new contacts surname or press cancel to exit.");
          if(surname == null)     finish();                         // if user clicks cancel
          if(surname.equals(""))
               int answer = JOptionPane.showConfirmDialog(null,"You did not enter a surname.\nAre you sure you wish to leave the surname empty?","No data entered",JOptionPane.YES_NO_OPTION);   // Asks if data was valid
               if(answer == JOptionPane.NO_OPTION)
                    surname = JOptionPane.showInputDialog(null,"Please enter the new contacts surname.");
          home = JOptionPane.showInputDialog(null,"Please enter the new contacts home number or press cancel to exit.");
          if(home == null)   finish();                    // if user clicks cancel
          work = JOptionPane.showInputDialog(null,"Please enter the new contacts work number or press cancel to exit.");
          if(work == null)     finish();                    // if user clicks cancel
          cell = JOptionPane.showInputDialog(null,"Please enter the new contacts cell number or press cancel to exit.");
          if(cell == null)     finish();                    // if user clicks cancel
     } // end of create new contact()
     // method to close applicatin
     public void finish()
     // method to search a contact
     public static void main(String[] args)
     { // start of main()
          // Set look and feel of interface
          try
          { // start of try block
               UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
          } // end of try block
          catch(Exception e)
          { // start of catch block
               JOptionPane.showMessageDialog(null,"There was an error in setting the look and feel of this application","Error",JOptionPane.INFORMATION_MESSAGE);
          } // end  of catch block
          Phonebook p = new Phonebook();
          p.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
          p.setJMenuBar(p.createMenuBar());
          p.setContentPane(p.createContentPane());
          p.setSize(520,500);
          p.setVisible(true);
          p.setResizable(false);
     } // end of main()
} //end of class

Answer 1

Yucca wrote:
Line 244 is where I test for if the user actuallu entered a String at all. Is there an alternative way of writing that code?
if(name.length() <=0)
               JOptionPane.showMessageDialog(null,"You did not enter a valid name.\nPlease make sure you enter data correctly.","Error",JOptionPane.ERROR_MESSAGE);
               createNew();                                   // To return to the create method
Change:
if(name == null)     finish();     To
if(name == null) {
    finish();
    return;
}