So im setting up this gui, but im getting this Nullpointer exception:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
	at addressbook.dnDisplay.jButton1ActionPerformed(dnDisplay.java:222)
	at addressbook.dnDisplay.access$600(dnDisplay.java:22)
	at addressbook.dnDisplay$7.actionPerformed(dnDisplay.java:128)
	at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
	at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
	at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
	at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
	at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
	at java.awt.Component.processMouseEvent(Component.java:6289)
	at javax.swing.JComponent.processMouseEvent(JComponent.java:3267)
	at java.awt.Component.processEvent(Component.java:6054)
	at java.awt.Container.processEvent(Container.java:2041)
	at java.awt.Component.dispatchEventImpl(Component.java:4652)
	at java.awt.Container.dispatchEventImpl(Container.java:2099)
	at java.awt.Component.dispatchEvent(Component.java:4482)
	at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4577)
	at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4238)
	at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4168)
	at java.awt.Container.dispatchEventImpl(Container.java:2085)
	at java.awt.Window.dispatchEventImpl(Window.java:2478)
	at java.awt.Component.dispatchEvent(Component.java:4482)
	at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:644)
	at java.awt.EventQueue.access$000(EventQueue.java:85)
	at java.awt.EventQueue$1.run(EventQueue.java:603)
	at java.awt.EventQueue$1.run(EventQueue.java:601)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
	at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:98)
	at java.awt.EventQueue$2.run(EventQueue.java:617)
	at java.awt.EventQueue$2.run(EventQueue.java:615)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:614)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
	at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

SearchModify.java

package addressbook;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.util.List; 
import javax.swing.JButton;
import javax.swing.Box;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.WindowConstants;
import javax.swing.BoxLayout;
import javax.swing.BorderFactory;
import javax.swing.JOptionPane;


public class dnDisplay extends javax.swing.JFrame {
    
    
   private javax.swing.ButtonGroup Type;
    private javax.swing.JRadioButton doctorRadio;
    private javax.swing.JTextField fName;
    private javax.swing.JButton jButton1;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JLabel jLabel3;
    private javax.swing.JLabel jLabel4;
    private javax.swing.JLabel jLabel5;
    private javax.swing.JLabel jLabel6;
    private javax.swing.JTextField lName;
    private javax.swing.JRadioButton nurseRadio;
    private javax.swing.JTextField Pass;
    private javax.swing.JComboBox Specialty;
    private javax.swing.JTextField Username;
    private List<Dn> results;
   private AddDoctorNurseQueries addDoctorNurseQueries;

 
   
    public dnDisplay() {
        initComponents();
       
    }

    private void initComponents() {

       // AddDoctorNurseQueries = new AddDoctorNurseQueries();
        Type = new javax.swing.ButtonGroup();
        jLabel1 = new javax.swing.JLabel();
        lName = new javax.swing.JTextField();
        jLabel2 = new javax.swing.JLabel();
        fName = new javax.swing.JTextField();
        jLabel3 = new javax.swing.JLabel();
        jLabel4 = new javax.swing.JLabel();
        jLabel5 = new javax.swing.JLabel();
        jLabel6 = new javax.swing.JLabel();
        Username = new javax.swing.JTextField();
        Pass = new javax.swing.JTextField();
        Specialty = new javax.swing.JComboBox();
        doctorRadio = new javax.swing.JRadioButton();
        nurseRadio = new javax.swing.JRadioButton();
        jButton1 = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jLabel1.setText("Add Doctor or Nurse");

        lName.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                lnameActionPerformed(evt);
            }
        });

        jLabel2.setText("Last Name: ");

        fName.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                fnameActionPerformed(evt);
            }
        });

        jLabel3.setText("First Name: ");

        jLabel4.setText("Username:");

        jLabel5.setText("Password: ");

        jLabel6.setText("Specialty: ");

        Pass.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                passwordActionPerformed(evt);
            }
        });

        Specialty.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "General Doctor", "Pediatrician", "Neurologist", "Plastic Surgeon", "Pediatrician", "Emergency Medicine Doctor", "Gynecologist" }));
        Specialty.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                specialtyActionPerformed(evt);
            }
        });

        Type.add(doctorRadio);
        doctorRadio.setText("Doctor");
        doctorRadio.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                doctorRadioActionPerformed(evt);
            }
        });

        Type.add(nurseRadio);
        nurseRadio.setText("Nurse");
        nurseRadio.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                nurseRadioActionPerformed(evt);
            }
        });

        jButton1.setText("Save");
           jButton1.addActionListener(new java.awt.event.ActionListener() {
          
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(95, 95, 95)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                    .addComponent(jLabel6)
                    .addComponent(jLabel5)
                    .addComponent(jLabel4)
                    .addComponent(jLabel2)
                    .addComponent(jLabel3))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(Pass, javax.swing.GroupLayout.DEFAULT_SIZE, 160, Short.MAX_VALUE)
                            .addComponent(Username, javax.swing.GroupLayout.DEFAULT_SIZE, 160, Short.MAX_VALUE)
                            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                                .addComponent(fName)
                                .addComponent(lName, javax.swing.GroupLayout.PREFERRED_SIZE, 160, javax.swing.GroupLayout.PREFERRED_SIZE))
                            .addComponent(Specialty, javax.swing.GroupLayout.Alignment.TRAILING, 0, 160, Short.MAX_VALUE))
                        .addGap(83, 83, 83))
                    .addGroup(layout.createSequentialGroup()
                        .addComponent(jLabel1)
                        .addContainerGap())))
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap(161, Short.MAX_VALUE)
                .addComponent(doctorRadio)
                .addGap(18, 18, 18)
                .addComponent(nurseRadio)
                .addGap(113, 113, 113))
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap(188, Short.MAX_VALUE)
                .addComponent(jButton1)
                .addGap(157, 157, 157))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addGap(37, 37, 37)
                .addComponent(jLabel1)
                .addGap(18, 18, 18)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(nurseRadio)
                    .addComponent(doctorRadio, javax.swing.GroupLayout.PREFERRED_SIZE, 26, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(13, 13, 13)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel2)
                    .addComponent(lName, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(fName, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jLabel3))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel4)
                    .addComponent(Username, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel5)
                    .addComponent(Pass, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel6)
                    .addComponent(Specialty, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(28, 28, 28)
                .addComponent(jButton1)
                .addGap(28, 28, 28))
        );

        pack();
    }// </editor-fold>

    private void lnameActionPerformed(java.awt.event.ActionEvent evt) {                                      
        // TODO add your handling code here:
    }                                     

    private void specialtyActionPerformed(java.awt.event.ActionEvent evt) {                                          
        // TODO add your handling code here:
    }                                         

    private void passwordActionPerformed(java.awt.event.ActionEvent evt) {                                         
        // TODO add your handling code here:
    }                                        

    private void fnameActionPerformed(java.awt.event.ActionEvent evt) {                                      
        // TODO add your handling code here:
    }       
    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                      
       int result = addDoctorNurseQueries.addPerson(  
                
               Type.getSelection().toString(),
                lName.getText(), 
                fName.getText(), 
                Username.getText(), 
                Pass.getText(), 
                Specialty.getSelectedItem().toString());
     
      if ( result == 1 )
         JOptionPane.showMessageDialog( this, "Nurse/Doc added!",
            "Person added", JOptionPane.PLAIN_MESSAGE );
      else
         JOptionPane.showMessageDialog( this, "Nurse/Doc not added!",
            "Error", JOptionPane.PLAIN_MESSAGE );
    }  

    private void nurseRadioActionPerformed(java.awt.event.ActionEvent evt) {                                           
        // TODO add your handling code here:
    }    
    

    private void doctorRadioActionPerformed(java.awt.event.ActionEvent evt) {                                            
        // TODO add your handling code here:
    }                                           

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {

            public void run() {
                new dnDisplay().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify
 
    
}

I have no idea whether your line numbering agrees with the numbering assigned by Daniweb, so I won't try to look at line 222 of the source here (though it's possible that it's the problem line)

Here's a procedure for fixing this sort of thing:
Open up your editor of choice and go to line 222. Find every object on that line. Prior to that line insert a println that outputs the name of the variable as a literal string, followed by a call to the object's toString() method.

Something like:

System.out.println("object1: " + object1.toString());
System.out.println("object2: " + object2.toString());

for each object you find on that line.
When you run it, you'll see something like

object1: null

Now you know which object is null. Trace back through the code. Where is the last place that you touched that object? It must be null after that instruction, so how did it get that way? (use another println to verify its state if necessary)

Objects don't set themselves to null - either it was never assigned a value, or you assigned it a null value.

This article has been dead for over six months. Start a new discussion instead.