[newbie] java.lang.NullPointerException

[jon80]

What kind of file does the following code expect? Why is it breaking?


:confused:

import java.net.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.util.*;
import javax.naming.*;
import javax.naming.directory.*;
import javax.swing.*;

/**
    This program demonstrates access to a hierarchical database through LDAP
*/
public class LDAPTest
{
    public static void main(String[] args)
    {
       JFrame frame = new LDAPFrame();
       frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
       frame.setVisible(true);
    }
}

 /**
    The frame that holds the data panel and the navigation buttons.
 */
 class LDAPFrame extends JFrame
 {
    public LDAPFrame()
    {
       setTitle("LDAPTest");
       setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);

       JPanel northPanel = new JPanel();
       northPanel.setLayout(new java.awt.GridLayout(1, 2, 3, 1));
       northPanel.add(new JLabel("uid", SwingConstants.RIGHT));
       uidField = new JTextField();
       northPanel.add(uidField);
       add(northPanel, BorderLayout.NORTH);

       JPanel buttonPanel = new JPanel();
       add(buttonPanel, BorderLayout.SOUTH);

       findButton = new JButton("Find");
       findButton.addActionListener(new
          ActionListener()
          {
             public void actionPerformed(ActionEvent event)
             {
                findEntry();
             }
          });
       buttonPanel.add(findButton);

       saveButton = new JButton("Save");
       saveButton.addActionListener(new
           ActionListener()
           {
              public void actionPerformed(ActionEvent event)
              {
                 saveEntry();
              }
           });
        buttonPanel.add(saveButton);

        deleteButton = new JButton("Delete");
        deleteButton.addActionListener(new
           ActionListener()
           {
              public void actionPerformed(ActionEvent event)
              {
                 deleteEntry();
              }
           });
        buttonPanel.add(deleteButton);

        addWindowListener(new
           WindowAdapter()
           {
              public void windowClosing(WindowEvent event)
              {
                 try
                 {
                    if (context != null) context.close();
                 }
                 catch (NamingException e)
                 {
                    e.printStackTrace();
                 }
              }
          });
     }

     /**
        Finds the entry for the uid in the text field.
     */
     public void findEntry()
     {
        try
        {
          if (scrollPane != null) remove(scrollPane);
          String dn = "uid=" + uidField.getText() + ",ou=people,dc=mycompany,dc=com";
          if (context == null) context = getContext();
          attrs = context.getAttributes(dn);
          dataPanel = new DataPanel(attrs);
          scrollPane = new JScrollPane(dataPanel);
          add(scrollPane, BorderLayout.CENTER);
          validate();
          uid = uidField.getText();
       }
       catch (NamingException e)
       {
          JOptionPane.showMessageDialog(this, e);
       }
       catch (IOException e)
       {
          JOptionPane.showMessageDialog(this, e);
       }
    }

    /**
       Saves the changes that the user made.
    */
    public void saveEntry()
    {
       try
       {
          if (dataPanel == null) return;
          if (context == null) context = getContext();
          if (uidField.getText().equals(uid)) // update existing entry
          {
             String dn = "uid=" + uidField.getText() + ",ou=people,dc=mycompany,dc=com";
             Attributes editedAttrs = dataPanel.getEditedAttributes();
             NamingEnumeration<? extends Attribute> attrEnum = attrs.getAll();
             while (attrEnum.hasMore())
             {
                Attribute attr = attrEnum.next();
                String id = attr.getID();
                Object value = attr.get();
                Attribute editedAttr = editedAttrs.get(id);
                if (editedAttr != null && !attr.get().equals(editedAttr.get()))
                   context.modifyAttributes(dn, DirContext.REPLACE_ATTRIBUTE,
                      new BasicAttributes(id, editedAttr.get()));
             }
          }
          else // create new entry
          {
             String dn = "uid=" + uidField.getText() + ",ou=people,dc=mycompany,dc=com";
             attrs = dataPanel.getEditedAttributes();
             Attribute objclass = new BasicAttribute("objectClass");
             objclass.add("uidObject");
             objclass.add("person");
             attrs.put(objclass);
             attrs.put("uid", uidField.getText());
             context.createSubcontext(dn, attrs);
          }

          findEntry();
       }
       catch (NamingException e)
       {
          JOptionPane.showMessageDialog(LDAPFrame.this, e);
          e.printStackTrace();
       }
       catch (IOException e)
       {
          JOptionPane.showMessageDialog(LDAPFrame.this, e);
          e.printStackTrace();
       }
    }

    /**
       Deletes the entry for the uid in the text field.
    */
    public void deleteEntry()
    {
       try
       {
          String dn = "uid=" + uidField.getText() + ",ou=people,dc=mycompany,dc=com";
          if (context == null) context = getContext();
          context.destroySubcontext(dn);
          uidField.setText("");
          remove(scrollPane);
          scrollPane = null;
          repaint();
       }
       catch (NamingException e)
       {
          JOptionPane.showMessageDialog(LDAPFrame.this, e);
          e.printStackTrace();
       }
       catch (IOException e)
       {
          JOptionPane.showMessageDialog(LDAPFrame.this, e);
          e.printStackTrace();
       }
    }

    /**
       Gets a context from the properties specified in the file ldapserver.properties
       @return the directory context
    */
    public static DirContext getContext()
       throws NamingException, IOException
    {
       Properties props = new Properties();
       FileInputStream in = new FileInputStream("ldapserver.properties");
       props.load(in);
       in.close();

       String url = props.getProperty("ldap.url");
       String username = props.getProperty("ldap.username");
       String password = props.getProperty("ldap.password");

       Hashtable<String, String> env = new Hashtable<String, String>();
       env.put(Context.SECURITY_PRINCIPAL, username);
       env.put(Context.SECURITY_CREDENTIALS, password);
       DirContext initial = new InitialDirContext(env);
       DirContext context = (DirContext) initial.lookup(url);

       return context;
    }

    public static final int DEFAULT_WIDTH = 300;
    public static final int DEFAULT_HEIGHT = 200;

    private JButton findButton;
    private JButton saveButton;
    private JButton deleteButton;

    private JTextField uidField;
    private DataPanel dataPanel;
    private Component scrollPane;

    private DirContext context;
    private String uid;
    private Attributes attrs;
 }

 /**
    This panel displays the contents of a result set.
 */
 class DataPanel extends JPanel
 {
    /**
       Constructs the data panel.
       @param attributes the attributes of the given entry
    */
    public DataPanel(Attributes attrs) throws NamingException
    {
       setLayout(new java.awt.GridLayout(0, 2, 3, 1));

       NamingEnumeration<? extends Attribute> attrEnum = attrs.getAll();
       while (attrEnum.hasMore())
       {
          Attribute attr = attrEnum.next();
          String id = attr.getID();

          NamingEnumeration<?> valueEnum = attr.getAll();
          while (valueEnum.hasMore())
          {
             Object value = valueEnum.next();
             if (id.equals("userPassword"))
                value = new String((byte[]) value);

             JLabel idLabel = new JLabel(id, SwingConstants.RIGHT);
             JTextField valueField = new JTextField("" + value);
             if (id.equals("objectClass"))
                valueField.setEditable(false);
             if (!id.equals("uid"))
             {
                add(idLabel);
                add(valueField);
             }
          }
       }
    }

    public Attributes getEditedAttributes()
    {
       Attributes attrs = new BasicAttributes();
       for (int i = 0; i < getComponentCount(); i += 2)
       {
          JLabel idLabel = (JLabel) getComponent(i);
          JTextField valueField = (JTextField) getComponent(i + 1);
          String id = idLabel.getText();
          String value = valueField.getText();
          if (id.equals("userPassword"))
             attrs.put("userPassword", value.getBytes());
          else if (!id.equals("") && !id.equals("objectClass"))
             attrs.put(id, value);
       }
       return attrs;
    }
}

Error
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at java.util.Hashtable.put(Hashtable.java:394)
at LDAPFrame.getContext(LDAPTest.java:215)
at LDAPFrame.findEntry(LDAPTest.java:102)
at LDAPFrame$1.actionPerformed(LDAPTest.java:49)
at javax.swing.AbstractButton.fireActionPerformed(Abs tractButton.java:19
95)
at javax.swing.AbstractButton$Handler.actionPerformed (AbstractButton.jav
a:2318)
at javax.swing.DefaultButtonModel.fireActionPerformed (DefaultButtonModel
.java:387)
at javax.swing.DefaultButtonModel.setPressed(DefaultB uttonModel.java:242
)
at javax.swing.plaf.basic.BasicButtonListener.mouseRe leased(BasicButtonL
istener.java:236)
at java.awt.Component.processMouseEvent(Component.jav a:6216)
at javax.swing.JComponent.processMouseEvent(JComponen t.java:3265)
at java.awt.Component.processEvent(Component.java:598 1)
at java.awt.Container.processEvent(Container.java:204 1)
at java.awt.Component.dispatchEventImpl(Component.jav a:4583)
at java.awt.Container.dispatchEventImpl(Container.jav a:2099)
at java.awt.Component.dispatchEvent(Component.java:44 13)
at java.awt.LightweightDispatcher.retargetMouseEvent( Container.java:4556
)
at java.awt.LightweightDispatcher.processMouseEvent(C ontainer.java:4220)

at java.awt.LightweightDispatcher.dispatchEvent(Conta iner.java:4150)
at java.awt.Container.dispatchEventImpl(Container.jav a:2085)
at java.awt.Window.dispatchEventImpl(Window.java:2475 )
at java.awt.Component.dispatchEvent(Component.java:44 13)
at java.awt.EventQueue.dispatchEvent(EventQueue.java: 599)
at java.awt.EventDispatchThread.pumpOneEventForFilter s(EventDispatchThre
ad.java:269)
at java.awt.EventDispatchThread.pumpEventsForFilter(E ventDispatchThread.
java:184)
at java.awt.EventDispatchThread.pumpEventsForHierarch y(EventDispatchThre
ad.java:174)
at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:169)

at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:161)

at java.awt.EventDispatchThread.run(EventDispatchThre ad.java:122)

[B]ldapserver.properties (originally named sample.ldif; then renamed it)[/B]
# Define top-level entry
dn: dc=mycompany,dc=com
objectClass: dcObject
objectClass: organization
dc: mycompany
o: Core Java Team
# Define an entry to contain people
# searches for users are based on this entry
dn: ou=people,dc=mycompany,dc=com
objectClass: organizationalUnit
ou: people
# Define a user entry for John Q. Public
dn: uid=jqpublic,ou=people,dc=mycompany,dc=com
objectClass: person
objectClass: uidObject
uid: jqpublic
sn: Public
cn: John Q. Public
telephoneNumber: +1 408 555 0017
userPassword: wombat

# Define a user entry for Jane Doe
dn: uid=jdoe,ou=people,dc=mycompany,dc=com
objectClass: person
objectClass: uidObject
uid: jdoe
sn: Doe
cn: Jane Doe
telephoneNumber: +1 408 555 0029
userPassword: heffalump

# Define an entry to contain LDAP groups
# searches for roles are based on this entry
dn: ou=groups,dc=mycompany,dc=com
objectClass: organizationalUnit
ou: groups

# Define an entry for the "techstaff" group
dn: cn=techstaff,ou=groups,dc=mycompany,dc=com
objectClass: groupOfUniqueNames
cn: techstaff
uniqueMember: uid=jdoe,ou=people,dc=mycompany,dc=com

# Define an entry for the "staff" group
dn: cn=staff,ou=groups,dc=mycompany,dc=com
objectClass: groupOfUniqueNames
cn: staff
uniqueMember: uid=jqpublic,ou=people,dc=mycompany,dc=com
uniqueMember: uid=jdoe,ou=people,dc=mycompany,dc=com

[makpandian]

i am not sure,But i think,You might have passed null value into the HashTable.

[Eranga]

Ya, somewhere cause with a null value. Cannot you debug near the hash table insertion? I think it's the easiest way to find the solution.