Exception Null

import java.sql.*;
import javax.sql.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import javax.crypto.Cipher;
import java.security.Key;
import javax.crypto.KeyGenerator;
import javax.crypto.BadPaddingException;
import javax.crypto.IllegalBlockSizeException;
import java.security.InvalidKeyException;

public class NewEncryption extends JFrame implements ActionListener
{
private static String algorithm = "AES";
private static Key key = null;
private static Cipher cipher = null;
ResultSet rs;
Connection con;
Connection con1;
Statement st;
String str = null;
PreparedStatement pst;
JLabel UI = new JLabel("User ID:");
JLabel pw = new JLabel("Password:");
JTextField UIt = new JTextField(20);
JTextField PWt = new JTextField(20);

JButton SingIn = new JButton("Sing In");
JButton SingUp = new JButton("Sing Up");

JPanel p = new JPanel();
JFrame f = new JFrame();

public NewEncryption()
{

this.setSize(800,600);
getContentPane().setLayout( null);

UI.setBounds(100,100,105,105);//User Label
UIt.setBounds(175,140,190,25);// User Text
getContentPane().add(UIt);
getContentPane().add(UI);

pw.setBounds(100,200,190,25);//Passsword Label
PWt.setBounds(175,200,190,25); //password Text
getContentPane().add(pw);
getContentPane().add(PWt);

SingIn.setBounds(400,400,100,30);
getContentPane().add(SingIn);
SingIn.setActionCommand("Sing In");
SingIn.addActionListener(this);

SingUp.setBounds(600,400,100,30);
getContentPane().add(SingUp);
SingUp.setActionCommand("Sing Up");
SingUp.addActionListener(this);
}

public void actionPerformed(ActionEvent e)
{
String str = e.getActionCommand();
try{
if(str.equals("Sing In"))
{
SingIn();
}
else if(str.equals("Sing Up"))
{
SingUp();
}
} catch(Exception E){System.out.print("ERR:\t"+E.getMessage());}
}
public static void main(String[] args)
{
NewEncryption N = new NewEncryption();
N.setVisible(true);
}

public void SingIn()
{
try{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");

}catch(Exception e) {System.out.print("Message:"+e.getMessage());}
try
{
String UI = UIt.getText();
// String PS = encrypt( PWt.getText() );
con1 = DriverManager.getConnection("jdbc

dbc:students","scott","tiger");
pst = con1.prepareStatement("select * from login where id='"+UI+"' ");
rs = pst.executeQuery( );
//System.out.print("show:"+UI);
while(rs.next())
{
/*if(PS.equals(rs.getString(2)))
{System.out.print("Welcome");}
else
{System.out.print("Sorry");}*/
String str = rs.getString(2);
String str1 = decrypt(str);
System.out.print("show:"+str);
}

//con1.close();
//pst.close();
}catch(SQLException sql){System.out.print("SQLException:"+sql.getMessage());}
catch(InvalidKeyException in){System.out.print("Invlid:"+in.getMessage());}
catch(BadPaddingException bd){System.out.print("Invlid:"+bd.getMessage());}
catch(IllegalBlockSizeException lb){System.out.print("Invlid:"+lb.getMessage());}
catch(Exception e){System.out.print("IN:"+e.getMessage());}

//catch(Exception n) {System.out.print("exc:"+n.getMessage());}

}

//shantibhushan
public void SingUp() //throws Exception
{
try{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");

}catch(Exception e) {System.out.print("Message:"+e.getMessage());}
try
{
String UI = UIt.getText();
String PS = encrypt( PWt.getText() );
con1 = DriverManager.getConnection("jdbc

dbc:students","scott","tiger");
pst = con1.prepareStatement("insert into login(id,psw)values(?,?)" );
pst.setString(1,UIt.getText());
pst.setString(2,PS.toString());
pst.executeQuery();
System.out.print("Coooo"+UI+":"+PS);

//con1.close();
//pst.close();
}catch(SQLException sql){System.out.print("SQLException"+sql.getMessage());}

catch(Exception n) {System.out.print("exc:"+n.getMessage());}

}

private static void setUp() throws Exception
{
key = KeyGenerator.getInstance(algorithm).generateKey();
cipher = Cipher.getInstance(algorithm);
}

public static String encrypt(String input) throws
InvalidKeyException,
BadPaddingException,
IllegalBlockSizeException,
Exception
{

cipher.init(Cipher.ENCRYPT_MODE, key);
byte[] encrypted =cipher.doFinal(input.getBytes());
String strs = cipher.doFinal(encrypted).toString();
return strs;
}
private static String decrypt(String encryptionBytes)
throws InvalidKeyException,
BadPaddingException,
IllegalBlockSizeException,
Exception
{byte[] by= encryptionBytes.getBytes();
cipher.init(Cipher.DECRYPT_MODE, key);
byte[] recoveredBytes = cipher.doFinal(by);
String recovered = new String(recoveredBytes);

return recovered;
}
}//end NewEncry

In the abov code i getting Null Exception I've needed solution of this problem! any body have help me
plz write your suggetion with code

the problem is with the key instance variable in public static String encrypt(String input) method .key value is null "cipher.init(Cipher.DECRYPT_MODE, key);" method. and
setUp method which is setting the key value is not being called from any place.

This doesn't seem to have anything to do with Threads (the topic of this forum), and the problem doesn't have to do with the API being used; so I'd call this a general Java question. Therefore I'm going to move it to Java in General (Intermediate).

Rahul, have a look at this for info about how to post easier-to-read code on the Ranch.

import java.sql.*;

public class result
{
static int i =0;
public static void main(String []args) throws Exception
{ con1 instance = new con1();
ResultSet rs;

try{
rs = instance.executeQuery("select * from client_master");
while(rs.next())
{
System.out.print("\n"+rs.getString(1)+"\t");
System.out.print("\t"+rs.getString(2)+"\t");
System.out.print("\t"+rs.getString(3)+"\t");
System.out.print("\t"+rs.getString(4)+"\t");
System.out.print("\t"+rs.getString(5)+"\n");
i++;
}
System.out.print("\nnum\t"+i);i =0;

System.out.print("\n............................This is New Table.........................................................\t");
System.out.print("\n............................This is New Table.........................................................\t");
System.out.print("\n............................This is New Table.........................................................\t");
rs = instance.executeQuery("select * from product_master");
while(rs.next())
{
System.out.print("\n"+rs.getString(1)+"\t");
System.out.print("\t"+rs.getString(2)+"\t");
System.out.print("\t"+rs.getString(3)+"\t");
System.out.print("\t"+rs.getString(4)+"\t");
System.out.print("\t"+rs.getString(5)+"\t");
System.out.print("\t"+rs.getString(6)+"\t");
System.out.print("\t"+rs.getString(7)+"\n");
i++;
} System.out.print("\nnum\t"+i);i=0;

rs = instance.executeQuery("select TRUNC(TO_NUMBER(sysdate - dd)) as days from date1");
while(rs.next())
{
System.out.print("\n"+rs.getString(1));
i++;
} System.out.print("\nnum\t"+i);

}catch(SQLException sql){System.out.print("mes:"+sql.getMessage());}

}
}

///////////////////////////////////////////
import java.sql.*;
public class con1
{
staticConnection con;
static Statement st;
public con1 ()
{
try
{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
con = DriverManager.getConnection("jdbc

dbc:studnets","scott", "tiger@ora");
st =con.createStatement();
}catch(SQLException sql){System.out.print("Error1:"+sql.getMessage());}
catch(ClassNotFoundException e){System.out.print("Error"+e.getMessage());}
}
publicstatic ResultSet executeQuery(String sql) throws Exception
{
return st.executeQuery(sql);
}
}

////////////////////////////////////////////////////////////////////////
/*
* Smartpad.java
*/

//THE IMPORTED LIBRARIES
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import javax.swing.text.*;
import java.text.*;
import java.util.*;
import javax.swing.undo.*;
import javax.swing.event.*;
import java.net.*;

/**
* Sample application using the simple text editor component that
* supports multiple fonts.
*
* Developed by Ms. Divya Bhatt, Mr. Dilip K. Pandey & Ms. Swati Jain.
* @version 30/10/2004
*/

public class Smartpad extends JFrame
{

//ALL THE VARIABLES USED IN THIS APPLICATION
JTextArea area = new JTextArea(0,0);
JScrollPane scroller = new JScrollPane(area);

public JPopupMenu pop = new JPopupMenu();

JMenu menu = new JMenu("Edit");
JMenuItem menuItem = new JMenuItem("copy");
JMenuItem menucut = new JMenuItem("cut");
JMenuItem menuclear = new JMenuItem("clear");
JMenuItem menupaste = new JMenuItem("paste");

JToolBar toolBar = new JToolBar();

JButton newFile = new JButton(new ImageIcon("new.jpg"));
JButton openFile = new JButton(new ImageIcon("open.jpg"));
JButton saveFile = new JButton(new ImageIcon("save.jpg"));

JButton cutFile = new JButton(new ImageIcon("cut.jpg"));
JButton copyFile = new JButton(new ImageIcon("copy.jpg"));
JButton pasteFile = new JButton(new ImageIcon("paste.jpg"));

JMenuBar menuBar = new JMenuBar();

JMenu FILE = new JMenu("File");
JMenu EDIT = new JMenu("Edit");
JMenu FORMAT = new JMenu("Format");
JMenu VIEW = new JMenu("View");
JMenu HELP = new JMenu("Help");
JMenu smart = new JMenu("Smart");

JMenuItem NEWFILE = new JMenuItem("New", new ImageIcon("new.jpg"));
JMenuItem OPENFILE = new JMenuItem("Open", new ImageIcon("open.jpg"));
JMenuItem SAVEFILE = new JMenuItem("Save", new ImageIcon("save.jpg"));
JMenuItem SAVEASFILE = new JMenuItem("Save As...");
JMenuItem PRINTFILE = new JMenuItem("Print...");
JMenuItem EXITFILE = new JMenuItem("Exit");

JMenuItem UNDOEDIT = new JMenuItem("Undo");
JMenuItem REDOEDIT = new JMenuItem("Redo");
JMenuItem COPYEDIT = new JMenuItem("copy");
JMenuItem CUTEDIT = new JMenuItem("cut");
JMenuItem PASTEDIT = new JMenuItem("paste");
JMenuItem DELETEDIT = new JMenuItem("Delete");
JMenuItem FINDEDIT = new JMenuItem("Find");
JMenuItem FINDNEXTEDIT = new JMenuItem("Find Next");
JMenuItem REPLACEDIT = new JMenuItem("Replace");
JMenuItem GOTOEDIT = new JMenuItem("Go To");
JMenuItem SELECTEDIT = new JMenuItem("Select All");
JMenuItem TIMEDIT = new JMenuItem("Time/Date");

JCheckBoxMenuItem WORDFORMAT = new JCheckBoxMenuItem("Word Wrap");
JMenuItem FONT = new JMenuItem("Font");

JCheckBoxMenuItem STATUSVIEW = new JCheckBoxMenuItem("Status Bar");

JCheckBoxMenuItem spell_check = new JCheckBoxMenuItem("Spell Check");
JMenuItem ABOUT = new JMenuItem("About");

String file = null;
String fileN;

boolean opened = false;

JPanel statusPanel = new JPanel();

JLabel statusLabel;

JPanel aboutPanel = new JPanel();

int ind = 0;

StringBuffer sbufer;
String findString;

fontSelector fontS = new fontSelector();

UndoManager undo = new UndoManager();
UndoAction undoAction = new UndoAction();
RedoAction redoAction = new RedoAction();

public Smartpad()
{
//DEFAULT TITLE OF FRAME
super("Smartpad :-)");

//SETS THE SIZE
this.setSize(800,600);

//SETS THE LAYOUT
this.getContentPane().setLayout(new BorderLayout());

//SETS WORD WRAP TO TRUE AS DEFAULT
area.setLineWrap(true);

//SETS FOCUS ON THE TEXTAREA
area.requestFocus(true);

//ADDS THE SCROLLPANE CONTAINING THE TEXTAREA TO THE CONTAINER
this.getContentPane().add(scroller, BorderLayout.CENTER);

//ADDS THE STATUSPANEL
this.getContentPane().add(statusPanel, BorderLayout.SOUTH);

//TO ENABLE DRAG MODE
area.setDragEnabled(true);

//SETS THE TOOLBAR TO BE STATIC I.E DISALLOW THE USER FROM CHANGING THE DOCKING POSITION
toolBar.setFloatable(false);

//ADD THE TOOLBAR
this.getContentPane().add(toolBar, BorderLayout.NORTH);

//ADD A MOUSELISTENER TO RIGHT CLICK FOR THE POPUPLISTENER
MouseListener popupListener = new PopupListener();
area.addMouseListener(popupListener);

//UNDO LISTENER ON AREA
area.getDocument().addUndoableEditListener(new MyUndoableEditListener());

//SETS THE MENUBAR
FILE.add(NEWFILE);
FILE.add(OPENFILE);
FILE.add(SAVEFILE);
FILE.add(SAVEASFILE);
FILE.addSeparator();
FILE.add(PRINTFILE);
FILE.addSeparator();
FILE.add(EXITFILE);

EDIT.add(undoAction);
EDIT.add(redoAction);
EDIT.add(CUTEDIT);
EDIT.add(COPYEDIT);
EDIT.add(PASTEDIT);
EDIT.add(DELETEDIT);
EDIT.addSeparator();
EDIT.add(FINDEDIT);
EDIT.add(FINDNEXTEDIT);
EDIT.add(REPLACEDIT);
EDIT.add(GOTOEDIT);
EDIT.addSeparator();
EDIT.add(SELECTEDIT);
EDIT.add(TIMEDIT);

FORMAT.add(WORDFORMAT);
WORDFORMAT.setSelected(true);
FORMAT.add(FONT);

VIEW.add(STATUSVIEW);
STATUSVIEW.setSelected(true);

HELP.add(ABOUT);

smart.add(spell_check);

FILE.setMnemonic(KeyEvent.VK_F);
menuBar.add(FILE);
EDIT.setMnemonic(KeyEvent.VK_E);
menuBar.add(EDIT);
FORMAT.setMnemonic(KeyEvent.VK_T);
menuBar.add(FORMAT);
VIEW.setMnemonic(KeyEvent.VK_V);
menuBar.add(VIEW);
HELP.setMnemonic(KeyEvent.VK_H);
menuBar.add(HELP);
smart.setMnemonic(KeyEvent.VK_H);
menuBar.add(smart);

//ADD MENUBAR TO THE FRAME
this.setJMenuBar(menuBar);

//ADD ITEMS TO THE POPUP
pop.add(undoAction);
pop.add(redoAction);
pop.addSeparator();
pop.add(menuItem);
pop.add(menucut);
pop.add(menupaste);
pop.add(menuclear);

//VALIDATION
newFile.setBorder(null);
openFile.setBorder(null);
saveFile.setBorder(null);
cutFile.setBorder(null);
copyFile.setBorder(null);
pasteFile.setBorder(null);

//ADD TO TOOLBAR
toolBar.add(newFile);
newFile.setToolTipText("New file");
toolBar.addSeparator();
toolBar.add(openFile);
openFile.setToolTipText("Open file");
toolBar.add(saveFile);
saveFile.setToolTipText("Save file");
toolBar.addSeparator();
toolBar.add(cutFile);
cutFile.setToolTipText("Cut");
toolBar.add(copyFile);
copyFile.setToolTipText("Copy");
toolBar.add(pasteFile);
pasteFile.setToolTipText("Paste");

//ACTION FOR NEW FILE ON THE TOOLBAR
newFile.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
opened = false;
if(area.getText().equals(""))
{
System.out.print("text is empty");
}
else
{
int confirm = JOptionPane.showConfirmDialog(null,
"Would you like to save?",
"New File",
JOptionPane.YES_NO_CANCEL_OPTION);

if( confirm == JOptionPane.YES_OPTION )
{
saveFile();
area.setText(null);
statusPanel.removeAll();
statusPanel.validate();
}
else
if( confirm == JOptionPane.CANCEL_OPTION )
{}
else if( confirm == JOptionPane.NO_OPTION )
{
area.setText(null);
statusPanel.removeAll();
statusPanel.validate();
}
}
}
});

////OPEN BUTTON ON THE TOOLBAR
openFile.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
openFile();
}
});

////SAVE BUTTON ON THE TOOLBAR
saveFile.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
saveFile();
}
});

//ACTION FOR CUT BUTTON ON THE TOOLBAR
cutFile.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
area.cut();
}
});

//ACTION FOR COPY BUTTON ON THE TOOLBAR
copyFile.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
area.copy();
}
});

//ACTION FOR PASTE BUTTON ON THE TOOLBAR
pasteFile.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
area.paste();
}
});

//ACTIONLISTENER FOR OTHER ITEMS ON THE TOOLBAR
//COPY BUTTON ON THE TOOLBAR
menuItem.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
area.copy();
menupaste.setEnabled(true);
pasteFile.setEnabled(true);
PASTEDIT.setEnabled(true);
}
});

//CUT BUTTON ON THE TOOLBAR
menucut.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
area.cut();
menupaste.setEnabled(true);
pasteFile.setEnabled(true);
PASTEDIT.setEnabled(true);
}
});

//PASTE BUTTON ON THE TOOLBAR
menupaste.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
area.paste();
}
});

//CLEAR BUTTON ON THE TOOLBAR
menuclear.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
area.setText(null);
}
});

//ACTIONLISTENER FOR ITEMS IN THE MENUBAR

//OPEN A NEW FILE
NEWFILE.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_N, ActionEvent.CTRL_MASK));
NEWFILE.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
opened = false;
int confirm = JOptionPane.showConfirmDialog(null,
"Would you like to save?",
"New File",
JOptionPane.YES_NO_CANCEL_OPTION);

if( confirm == JOptionPane.YES_OPTION )
{
saveFile();
area.setText(null);
statusPanel.removeAll();
statusPanel.validate();
}
else
if( confirm == JOptionPane.CANCEL_OPTION )
{}
else
{
area.setText(null);
statusPanel.removeAll();
statusPanel.validate();
}
}
});

//SAVE OPTION. HAS A VALIDATION CHECK THAT CHECKS WETHER ITS AN OPENED FILE OR NEW FILE
SAVEFILE.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_S, ActionEvent.CTRL_MASK));
SAVEFILE.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
saveFile();
}
});

//OPTION THAT WILL BRING UP A DIALOG WHICH SAVES THE FILE WITH A NAME AND FORMAT DESIRED
SAVEASFILE.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
opened = false;
saveFile();
}
});
SELECTEDIT.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_A, ActionEvent.CTRL_MASK));
SELECTEDIT.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
area.selectAll();
}
});

//PRINTS WHATEVER IS IN THE TEXT AREA
PRINTFILE.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_P, ActionEvent.CTRL_MASK));
PRINTFILE.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
if(area.getText().equals(""))
JOptionPane.showMessageDialog(null, "Text Area is empty.");
else
print(createBuffer());

}
});

//ACTION FOR STATUS BUTTON
STATUSVIEW.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
if(STATUSVIEW.isSelected())
statusPanel.setVisible(true);
else
statusPanel.setVisible(false);
}
});

//ACTION FOR OPEN BUTTON
OPENFILE.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_O,ActionEvent.CTRL_MASK));
OPENFILE.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
openFile();
}
});

//ACTION FOR CUT BUTTON
CUTEDIT.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_X, ActionEvent.CTRL_MASK));
CUTEDIT.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
area.cut();
}
});

//ACTION FOR COPY BUTTON
COPYEDIT.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_C, ActionEvent.CTRL_MASK));
COPYEDIT.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
area.copy();
}
});

//ACTION FOR PASTE BUTTON
PASTEDIT.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_V, ActionEvent.CTRL_MASK));
PASTEDIT.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
area.paste();
}
});

//FONT SELECTOR OPTION
FONT.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_F, ActionEvent.CTRL_MASK));
FONT.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
fontS.setVisible(true);
fontS.okButton.addActionListener(new ActionListener ()
{
public void actionPerformed(ActionEvent ae)
{
Font selectedFont = fontS.returnFont();
area.setFont(selectedFont);
fontS.setVisible(false);
}
});

fontS.cancelButton.addActionListener(new ActionListener ()
{
public void actionPerformed(ActionEvent ae)
{
fontS.setVisible(false);
}
});
}
});

//PRINTS THE SYSTEM DATE AND TIME IN THE EDITOR
TIMEDIT.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
Date currentDate;
SimpleDateFormat formatter;
String dd;
formatter = new SimpleDateFormat("KK:mm aa MMMMMMMMM dd yyyy", Locale.getDefault());
currentDate = new java.util.Date();
dd = formatter.format(currentDate);
area.insert(dd,area.getCaretPosition());
}
});

//FINDS A WORD IN THE EDITOR
FINDEDIT.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
try
{
sbufer = new StringBuffer(area.getText());
findString = JOptionPane.showInputDialog(null, "Find");
ind = sbufer.indexOf(findString);
area.setCaretPosition(ind);
area.setSelectionStart(ind);
area.setSelectionEnd(ind+findString.length());
}
catch(IllegalArgumentException npe)
{
JOptionPane.showMessageDialog(null, "String not found");
}catch(NullPointerException nfe){}
}
});

//FINDS A WORD IN THE EDITOR
FINDNEXTEDIT.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
try
{
sbufer = new StringBuffer(area.getText());
findString = JOptionPane.showInputDialog(null, "Find");
ind = sbufer.indexOf(findString, area.getCaretPosition());
area.setCaretPosition(ind);
area.setSelectionStart(ind);
area.setSelectionEnd(ind+findString.length());
}
catch(IllegalArgumentException npe)
{
JOptionPane.showMessageDialog(null, "String not found");
}catch(NullPointerException nfe){}
}
});

//EXITS THE APPLICATION AND CHECKS FOR ANY CHANGES MADE
EXITFILE.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_E, ActionEvent.CTRL_MASK));
EXITFILE.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
int confirm = JOptionPane.showConfirmDialog(null,
"Would you like to save?",
"Exit Application",
JOptionPane.YES_NO_CANCEL_OPTION);

if( confirm == JOptionPane.YES_OPTION )
{
saveFile();
dispose();
System.exit(0);
}
else
if( confirm == JOptionPane.CANCEL_OPTION )
{}
else
{
dispose();
System.exit(0);
}
}
});

//ACTION FOR REPLACE OPTION
REPLACEDIT.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
try
{
String replace = JOptionPane.showInputDialog(null, "Replace");
area.replaceSelection(replace);
}catch(NumberFormatException nfe){}
}
});

//ACTION FOR GO TO OPTION
GOTOEDIT.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
try
{
Element root = area.getDocument().getDefaultRootElement();
Element paragraph=root.getElement(Integer.parseInt(JOptionPane.showInputDialog(null, "Go to line")));
area.setCaretPosition(paragraph.getStartOffset()-1);
}catch(NullPointerException npe)
{
JOptionPane.showMessageDialog(null, "Invalid line number");
}catch(NumberFormatException nfe)
{

}
}
});

//ACTION FOR DELETE OPTION
DELETEDIT.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
area.replaceSelection(null);
}
});

//SETS THE LINEWRAP OT TRUE OR FALSE
WORDFORMAT.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
if(WORDFORMAT.isSelected())
area.setLineWrap(true);
else
area.setLineWrap(false);
}
});

//ABOUT
ABOUT.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_F2, ActionEvent.CTRL_MASK));
ABOUT.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
URL img = getClass().getResource("logo.jpg");
String imagesrc = "<img src=\"" + img + "\" width=\"323\" height=\"185\">";
String message = "Application using 'Swing' in JAVA\n"+
"Developed by Ms. Divya, Mr. Dilip & Ms. Swati\n"+
"Version 3-/10/2004\n"+
"Not for use without acknowldedgment of the Developer Team\n"+
"Please dont reuse this code without prior notice.\n"+
"The application is submitted as minor project to IPER, Bhopal.\n";

JOptionPane.showMessageDialog(aboutPanel,"<html><center>" + imagesrc + "<br>" + message);
}
});

//CLOSES THE WINDOW WHEN THE CLOSE BUTTON IS PRESSED
addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
int confirm = JOptionPane.showConfirmDialog(null,
"Would you like to save?",
"Exit Application",
JOptionPane.YES_NO_CANCEL_OPTION);

if( confirm == JOptionPane.YES_OPTION )
{
saveFile();
dispose();
System.exit(0);
}
else
if( confirm == JOptionPane.CANCEL_OPTION )
{

}
else
{
dispose();
System.exit(0);
}
}
});

}

//MAIN FUNCTION.
public static void main(String args[])
{
Smartpad l = new Smartpad();
l.setVisible(true);
}

//FUNCTION CALLED BY THE SAVE BUTTON
public void saveFile()
{
String line = area.getText();
if(opened==true)
{
try
{
FileWriter output = new FileWriter(file);
BufferedWriter bufout = new BufferedWriter(output);
bufout.write(line, 0, line.length());
JOptionPane.showMessageDialog(null, "Save Successful");
bufout.close();
output.close();
}catch(IOException ioe){ioe.printStackTrace();}
}
else
{
JFileChooser fc = new JFileChooser();
int result = fc.showSaveDialog(new JPanel());

if(result == JFileChooser.APPROVE_OPTION)
{
fileN = String.valueOf(fc.getSelectedFile());

try
{
FileWriter output = new FileWriter(fileN);
BufferedWriter bufout = new BufferedWriter(output);
bufout.write(line, 0, line.length());
JOptionPane.showMessageDialog(null, "Save Successful");
bufout.close();
output.close();
opened = true;
}catch(IOException ioe){ioe.printStackTrace();}
}
}
}

//PRINT FUNCTION
public String createBuffer()
{
String buffer;
buffer = area.getText();
return buffer;
}

private void print(String s)
{
StringReader sr = new StringReader(s);
LineNumberReader lnr = new LineNumberReader(sr);
Font typeface = new Font("Monospaced", Font.PLAIN, 12);
Properties p = new Properties();
PrintJob pjob = getToolkit().getPrintJob(this, "Print report", p);

if (pjob != null) {
Graphics pg = pjob.getGraphics();
if (pg != null) {
FontMetrics fm = pg.getFontMetrics(typeface);
int margin = 20;
int pageHeight = pjob.getPageDimension().height - margin;
int fontHeight = fm.getHeight();
int fontDescent = fm.getDescent();
int curHeight = margin;

String nextLine;
pg.setFont (area.getFont());

try
{
do
{
nextLine = lnr.readLine();
if (nextLine != null) {
if ((curHeight + fontHeight) > pageHeight)
{ // New Page
pg.dispose();
pg = pjob.getGraphics();
curHeight = margin;
}

curHeight += fontHeight;

if (pg != null)
{
pg.setFont (typeface);
pg.drawString (nextLine, margin, curHeight - fontDescent);
}
}
}
while (nextLine != null);

}
catch (EOFException eof)
{
}
catch (Throwable t)
{
t.printStackTrace();
}
}
pg.dispose();
}
if (pjob != null)
pjob.end();
}

//FUNCTION TO OPEN THE FILE
public void openFile()
{
statusPanel.removeAll();
statusPanel.validate();
area.setText(null);
JFileChooser fc = new JFileChooser();
int result = fc.showOpenDialog(new JPanel());

if(result == JFileChooser.APPROVE_OPTION)
{
String file = String.valueOf(fc.getSelectedFile());
//String dirn = fc.getDirectory();

File fil = new File(file);
newFile.setEnabled(false);

//START THIS THREAD WHILE READING FILE
Thread loader = new FileLoader(fil, area.getDocument());
loader.start();
statusPanel.removeAll();
statusPanel.revalidate();
}else{}
}

//CLASS FOR THE MOUSELIsTENER
class PopupListener extends MouseAdapter {

public void mousePressed(MouseEvent e) {

maybeShowPopup(e);
}

public void mouseReleased(MouseEvent e) {
maybeShowPopup(e);
}

private void maybeShowPopup(MouseEvent e) {
if (e.isPopupTrigger()) {
pop.show(e.getComponent(),
e.getX(), e.getY());
}
}
}

//CLASS FOR UNDOLISTENER
public class MyUndoableEditListener
implements UndoableEditListener
{
public void undoableEditHappened(UndoableEditEvent e) {
//Remember the edit and update the menus
undo.addEdit(e.getEdit());
undoAction.update();
redoAction.update();
}
}

/**
* Thread to load a file into the text storage model
*/
class FileLoader extends Thread {

JLabel state;

FileLoader(File f, Document doc) {
setPriority(4);
this.f = f;
this.doc = doc;
}

public void run() {
try {
// initialize the statusbar
statusPanel.removeAll();
JProgressBar progress = new JProgressBar();
progress.setMinimum(0);
progress.setMaximum((int) f.length());
statusPanel.add(new JLabel("opened so far "));
statusPanel.add(progress);
statusPanel.revalidate();

// try to start reading
Reader in = new FileReader(f);
char[] buff = new char[4096];
int nch;
while ((nch = in.read(buff, 0, buff.length)) != -1) {
doc.insertString(doc.getLength(), new String(buff, 0, nch), null);
progress.setValue(progress.getValue() + nch);
}

// we are done... get rid of progressbar
statusPanel.removeAll();
statusPanel.revalidate();

}
catch (IOException e) {
System.err.println(e.toString());
}
catch (BadLocationException e) {
System.err.println(e.getMessage());
}
newFile.setEnabled(true);
}
Document doc;
File f;
}

//UNDO AND REDOACTION CLASSES
//THIS PASRT OF CODE WAS TAKEN FROM THE NOTEPAD DEMO FOUND IN THE JDK1.4.1 DEMO DIRECTORY
class UndoAction extends AbstractAction {
public UndoAction() {
super("Undo");
setEnabled(false);
}

public void actionPerformed(ActionEvent e) {
try {
undo.undo();
} catch (CannotUndoException ex) {
System.out.println("Unable to undo: " + ex);
ex.printStackTrace();
}
update();
redoAction.update();
}

protected void update() {
if(undo.canUndo()) {
setEnabled(true);
putValue("Undo", undo.getUndoPresentationName());
}
else {
setEnabled(false);
putValue(Action.NAME, "Undo");
}
}
}

class RedoAction extends AbstractAction {
public RedoAction() {
super("Redo");
setEnabled(false);
}

public void actionPerformed(ActionEvent e) {
try {
undo.redo();
} catch (CannotRedoException ex) {
System.out.println("Unable to redo: " + ex);
ex.printStackTrace();
}
update();
undoAction.update();
}

protected void update() {
if(undo.canRedo()) {
setEnabled(true);
putValue("Redo", undo.getRedoPresentationName());
}
else {
setEnabled(false);
putValue(Action.NAME, "Redo");
}
}
}

//END MAIN CLASS
}
////////////////////////////////////////////////////////////////////////

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class fontSelector extends JDialog
{

String fontString[] = GraphicsEnvironment.getLocalGraphicsEnvironment().getAvailableFontFamilyNames();
JComboBox fontSelector = new JComboBox(fontString);
JLabel fontLabel = new JLabel("Select Font");

String fontSizeString[] = {"10","12","14","16","18","20","22","24","28"};
JComboBox fontSize = new JComboBox(fontSizeString);
JLabel sizeLabel = new JLabel("Select Size");

String fontStyleString[] = {"Normal","Bold","Italic","Bold Italic"};
JComboBox fontStyle = new JComboBox(fontStyleString);
JLabel styleLabel = new JLabel("Select Style");

JButton okButton = new JButton("OK");
JButton cancelButton = new JButton("Cancel");

JLabel previewLabel = new JLabel("Preview:");
JLabel preview = new JLabel(" AaBbCc");

Font selectedFont;

public fontSelector()
{
this.setSize(300,200);
this.setBackground(Color.blue);
this.setTitle("Font Selector");

getContentPane().setLayout(null);

fontLabel.setBounds(10,10,100,20);
fontSelector.setBounds(110,10,150,20);
sizeLabel.setBounds(10,35,100,20);
fontSize.setBounds(110,35,100,20);
styleLabel.setBounds(10,60,100,20);
fontStyle.setBounds(110,60,100,20);

okButton.setBounds(10,100,100,20);
cancelButton.setBounds(110,100,100,20);

previewLabel.setBounds(50,130,100,30);
preview.setBorder(BorderFactory.createLineBorder(Color.black));
preview.setBounds(120,130,70,30);

getContentPane().add(fontLabel);
getContentPane().add(fontSelector);
getContentPane().add(sizeLabel);
getContentPane().add(fontSize);
getContentPane().add(styleLabel);
getContentPane().add(fontStyle);
getContentPane().add(okButton);
getContentPane().add(cancelButton);
getContentPane().add(previewLabel);
getContentPane().add(preview);

//SETS THE PREVIEW
fontSelector.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
preview.setFont(new Font(String.valueOf(fontSelector.getSelectedItem()),fontStyle.getSelectedIndex(),14));
}
});
fontStyle.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
preview.setFont(new Font(String.valueOf(fontSelector.getSelectedItem()),fontStyle.getSelectedIndex(),14));
}
});
}

public Font returnFont()
{
String fontSS = String.valueOf(fontSelector.getSelectedItem());
int fontSZ = Integer.parseInt(String.valueOf(fontSize.getSelectedItem()));
int fontST = fontStyle.getSelectedIndex();

selectedFont = new Font(fontSS,fontST,fontSZ);

return selectedFont;
}

}

Do you have a question? If so, find this thread over in Java in General (Intermediate), where I'm really moving it this time, and tell us what it is.

I am assuming when you say "Exception Null", you are referring to a NullPointerException. Null pointer exception stacktraces, generally tell you the class, and line number, which the exception occurred. That should be a good starting point to look.

Henry

Have a look at this: How to resolve a java.lang.NullPointerException