what is Dshield

DShield is a community-based collaborative firewall log correlation system. It receives logs from volunteers world wide and uses them to analyze attack trends. It is used as the data collection engine behind the SANS Internet Storm Center (ISC). It was officially launched end of November 2000

www.dshield.org/

CLock CAN TAlk REALLy

import java.util.*;
public class CLockTAlk
{
   public static void main(String[]args)
   {
       // get current time and date
       Calendar now = Calendar.getInstance();
       int hour = now.get(Calendar.HOUR_OF_DAY);
       int minute = now.get(Calendar.MINUTE);
       int month = now.get(Calendar.MONTH)+ 1;
       int day = now.get(Calendar.DAY_OF_MONTH);
       int year = now.get(Calendar.YEAR);

       // display gretting
       if (hour < 12)
           System.out.println("Good morning Sir!
Have you ate breakfast
yet?");
       else if (hour < 18)
           System.out.println("Good afternoon Sir!
Have you ate lunch
yet?");
       else
           System.out.println("Good evening Sir!
Have you ate dinner
yet?");

       // begin time message by showing the minutes
       System.out.print("It is");
       if (minute != 0)
       {
           System.out.print(" " + minute + " ");
           System.out.print( (minute != 1) ? "minutes" : "minute");
           System.out.print(" past");
       }

       // display the hour
           System.out.print(" ");
           System.out.print( (hour > 12) ? (hour - 12) : hour );
           System.out.print(" 0'clock on ");

           // display the name of the month
           switch (month)
           {
               case 1:
                   System.out.print("January");
                   break;
               case 2:
                   System.out.print("February");
                   break;
               case 3:
                   System.out.print("March");
                   break;
               case 4:
                   System.out.print("April");
                   break;
               case 5:
                   System.out.print("May");
                   break;
               case 6:
                   System.out.print("June");
                   break;
               case 7:
                   System.out.print("July");
                   break;
               case 8:
                   System.out.print("August");
                   break;
               case 9:
                   System.out.print("September");
                   break;
               case 10:
                   System.out.print("October");
                   break;
               case 11:
                   System.out.print("November");
                   break;
               case 12:
                   System.out.print("December");
          }

           // display the date and year
           System.out.println(" " + day + ", " + year + ".");
   }

}

Automatically create and delete a file

import java.util.*;
import java.io.*;
public class ab extends TimerTask
    {
     static File file;
     public static void main(String[] args ) throws IOException
         {
         file = new File ("test.dat");
         if (! file.exists() )
             {
             file.createNewFile();
         }
         System.out.println("File Created");
         ab test = new ab();
         Timer t = new Timer ();
         t.schedule(test, 30*1000L);
         try
             {
             while (file.exists())
                 {
                 System.out.print('.');
                 Thread.sleep(1000);
             }
         }
         catch (InterruptedException ie)
             {
             System.out.println("Error");
         }
         System.exit(0);
     } //end of main
     public void run()
         {
         file.delete();
     }
} //end of public class ab

This is a simple text clock. See

javax.swing.Timer for an explanation of how use this simple timer class.




import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import java.util.Calendar;      // only need this one class

/// TextClock
public class TextClock {
  
main
    public static void main(String[] args) {
        JFrame clock = new TextClockWindow();
        clock.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        clock.setVisible(true);
    }//end main
}//endclass TextClock


////// TextClockWindow
class TextClockWindow extends JFrame {
  
instance variables
    private JTextField timeField;  // set by timer listener

  
constructor
    public TextClockWindow() {
        // Build the GUI - only one panel
        timeField = new JTextField(6);
        timeField.setFont(new Font("sansserif", Font.PLAIN, 48));

        Container content = this.getContentPane();
        content.setLayout(new FlowLayout());
        content.add(timeField);
      
        this.setTitle("Text Clock");
        this.pack();

        // Create a 1-second timer and action listener for it.
        // Specify package because there are two Timer classes
        javax.swing.Timer t = new javax.swing.Timer(1000,
              new ActionListener() {
                  public void actionPerformed(ActionEvent e) {
                      Calendar now = Calendar.getInstance();
                      int h = now.get(Calendar.HOUR_OF_DAY);
                      int m = now.get(Calendar.MINUTE);
                      int s = now.get(Calendar.SECOND);
                      timeField.setText("" + h + ":" + m + ":" + s);
                  }
              });
        t.start();  // Start the timer
    }//end constructor
}//endclass TextClock

Simple Mathematical Calculations 2

import java.awt.*;
import java.awt.event.*;

// Java extension packages
import javax.swing.*;

public class Points extends JApplet implements ActionListener {
   JTextField x1Input, x2Input, y1Input, y2Input;
   JLabel labelX1, labelY1, labelX2, labelY2;

   // set up GUI components
   public void init()
   {
      labelX1 = new JLabel( "Enter X1: " );
      labelY1 = new JLabel( "Enter Y1: " );
      labelX2 = new JLabel( "Enter X2: " );
      labelY2 = new JLabel( "Enter Y2: " );
      x1Input = new JTextField( 4 );
      x2Input = new JTextField( 4 );
      y1Input = new JTextField( 4 );
      y2Input = new JTextField( 4 );
      y2Input.addActionListener( this );

      Container container = getContentPane();
      container.setLayout( new FlowLayout() );
      container.add( labelX1 );
      container.add( x1Input );
      container.add( labelY1 );
      container.add( y1Input );
      container.add( labelX2 );
      container.add( x2Input );
      container.add( labelY2 );
      container.add( y2Input );
   }

   // display distance between user input points
   public void actionPerformed( ActionEvent e )
   {
      double x1, y1, x2, y2;

 // read in two points
      x1 = Double.parseDouble( x1Input.getText() );
      y1 = Double.parseDouble( y1Input.getText() );
      x2 = Double.parseDouble( x2Input.getText() );
      y2 = Double.parseDouble( y2Input.getText() );

      double theDistance = distance( x1, y1, x2, y2 );
      showStatus( "Distance is " + theDistance );
   }

   // calculate distance between two points
   public double distance( double x1, double y1,
      double x2, double y2 )
   {
      return Math.sqrt( Math.pow( ( x1 - x2 ), 2 ) +
         Math.pow( ( y1 - y2 ), 2 ) );
   }

} // end class Points

Simple Mathematical Calculations

// Exercise 3.12 Solution: Multiples.java
// Given two doubles as input, the program determines if the first// is a multiple of the second.

// Java core packages
import java.awt.Graphics;   // import class Graphics

// Java extension packages
import javax.swing.*;       // import package javax.swing

public class Multiples extends JApplet {
   String result;   // output display String

   // initialize applet by obtaining values from user
   public void init()
   {
      String firstNumber;    // first String entered by user
      String secondNumber;   // second String entered by user
      double number1;        // first number to compare
      double number2;        // second number to compare

      // read first number from user as a String
      firstNumber =
         JOptionPane.showInputDialog( "Enter first floating-point number:" );

      // read second number from user as a String
      secondNumber =
         JOptionPane.showInputDialog( "Enter second floating-point number:" );

      // convert numbers from type String to type double
      number1 = Double.parseDouble( firstNumber );
      number2 = Double.parseDouble( secondNumber );

      if ( number1 % number2 == 0 )
       result  = number1 + " is a multiple of " + number2;

      if ( number1 % number2 != 0 )
       result  = number1 + " is not a multiple of " + number2;

   }  // end method init

   // draw results on applet's background
   public void paint( Graphics g )
   {
      // draw result as a String at (25, 25)
      g.drawString( result, 25, 25 );

   }  // end method paint

}  // end class OddEven

Audio channel player

import java.io.File;
import java.io.InputStream;
import java.io.IOException;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;

import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.AudioInputStream;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.LineUnavailableException;
import javax.sound.sampled.LineListener;
import javax.sound.sampled.LineEvent;
import javax.sound.sampled.Mixer;
import javax.sound.sampled.SourceDataLine;
import javax.sound.sampled.DataLine;
import javax.sound.sampled.FloatControl;
import javax.sound.sampled.BooleanControl;


public class AudioChannelPlayer
{
private static final boolean DEBUG = true;
private static final int BUFFER_SIZE = 16384;



public static void main(String[] args)
{
 // TODO: set AudioFormat after the first soundfile
 AudioFormat audioFormat = new AudioFormat(
  AudioFormat.Encoding.PCM_SIGNED,
  44100.0F, 16, 2, 4, 44100.0F, true);
 SourceDataLine  line = null;

 try
 {
  DataLine.Info info = new DataLine.Info(SourceDataLine.class, audioFormat);
  line = (SourceDataLine) AudioSystem.getLine(info);
  line.open(audioFormat, line.getBufferSize());
 }
 catch (LineUnavailableException e)
 {
  e.printStackTrace();
 }
 line.start();
 AudioChannel channel = new AudioChannel(line);
 channel.start();
 for (int nArgPos = 0; nArgPos < args.length; nArgPos++)
 {
  if (args[nArgPos].startsWith("-s"))
  {
   String strDuration = args[nArgPos].substring(2);
   int nDuration = Integer.parseInt(strDuration);
   handleSilence(nDuration, channel);
  }
  else
  {
   handleFile(args[nArgPos], channel);
  }

 }
 // TODO: instead of waiting a fixed amount of time, wait until the queue of AudioChannel is empty.
 try
 {
  Thread.sleep(10000);
 }
 catch (InterruptedException e)
 {
 }
}


private static void handleFile(String strFilename, AudioChannel channel)
{
 File audioFile = new File(strFilename);
 AudioInputStream audioInputStream = null;
 try
 {
  audioInputStream = AudioSystem.getAudioInputStream(audioFile);
 }
 catch (Exception e)
 {
  /*
   * In case of an exception, we dump the exception
   * including the stack trace to the console output.
   * Then, we exit the program.
   */
  e.printStackTrace();
  System.exit(1);
 }
 if (audioInputStream != null)
 {
  boolean bSuccessfull = channel.addAudioInputStream(audioInputStream);
  if (! bSuccessfull)
  {
   out("Warning: could not enqueue AudioInputStream; presumably formats don't match!");
  }
 }
}


private static void handleSilence(int nDuration, AudioChannel channel)
{
}



private static void out(String strMessage)
{
 System.out.println(strMessage);
}
}


/*** AudioChannelPlayer.java ***/

Built by Text2Html

BlowfishCipher

package com.ack.security.jce;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.swing.JOptionPane;

/**
 * This program demonstrates how to encrypt/decrypt input
 * using the Blowfish Cipher with the Java Cryptograhpy.
 *
 */
public class BlowfishCipher {

  public static void main(String[] args) throws Exception {

    // create a key generator based upon the Blowfish cipher
    KeyGenerator keygenerator = KeyGenerator.getInstance("Blowfish");

    // create a key
    SecretKey secretkey = keygenerator.generateKey();

    // create a cipher based upon Blowfish
    Cipher cipher = Cipher.getInstance("Blowfish");

    // initialise cipher to with secret key
    cipher.init(Cipher.ENCRYPT_MODE, secretkey);

    // get the text to encrypt
    String inputText = JOptionPane.showInputDialog("Input your message: ");

    // encrypt message
    byte[] encrypted = cipher.doFinal(inputText.getBytes());

    // re-initialise the cipher to be in decrypt mode
    cipher.init(Cipher.DECRYPT_MODE, secretkey);

    // decrypt message
    byte[] decrypted = cipher.doFinal(encrypted);

    // and display the results
    JOptionPane.showMessageDialog(JOptionPane.getRootFrame(),
                                  "encrypted text: " + new String(encrypted) + "\n" +
                                  "decrypted text: " + new String(decrypted));

    // end example
    System.exit(0);
  }
}

Listing all running threads

// Find the root thread group
ThreadGroup root = Thread.currentThread().getThreadGroup().getParent();
    while (root.getParent() != null) {
     root = root.getParent();
}

// Visit each thread group
visit(root, 0);

// This method recursively visits all thread groups under `group'.
    public static void visit(ThreadGroup group, int level) {
     // Get threads in `group'
     int numThreads = group.activeCount();
     Thread[] threads = new Thread[numThreads*2];
     numThreads = group.enumerate(threads, false);
  
     // Enumerate each thread in `group'
         for (int i=0; i         // Get thread
         Thread thread = threads[i];
     }
  
     // Get thread subgroups of `group'
     int numGroups = group.activeGroupCount();
     ThreadGroup[] groups = new ThreadGroup[numGroups*2];
     numGroups = group.enumerate(groups, false);
  
     // Recursively visit each subgroup
         for (int i=0; i         visit(groups[i], level+1);
     }
}

//Here's an example of some thread groups that contain some threads:
java.lang.ThreadGroup[name=system,maxpri=10]
Thread[Reference Handler,10,system]
Thread[Finalizer,8,system]
Thread[Signal Dispatcher,10,system]
Thread[CompileThread0,10,system]
java.lang.ThreadGroup[name=main,maxpri=10]
Thread[main,5,main]
Thread[Thread-1,5,main]

Demonstrating the runnable interface

  import java.awt.*;

 import java.awt.event.*;

 import javax.swing.*;

 public class RandomCharacters extends JApplet implements Runnable, ActionListener 

 {

private String alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

private JLabel outputs[];

private JCheckBox checkboxes[];

private final static int SIZE = 3;

private Thread threads[];

private boolean suspended[];

public void init()

{

outputs = new JLabel[ SIZE ];

checkboxes = new JCheckBox[ SIZE ];

threads = new Thread[ SIZE ];

suspended = new boolean[ SIZE ];

Container c = getContentPane();

c.setLayout( new GridLayout( SIZE, 2, 5, 5 ) );

for ( int i = 0; i < SIZE; i++ ) 

{

outputs[ i ] = new JLabel();

outputs[ i ].setBackground( Color.green );

outputs[ i ].setOpaque( true );

c.add( outputs[ i ] );

checkboxes[ i ] = new JCheckBox( "Suspended" );

checkboxes[ i ].addActionListener( this );

c.add( checkboxes[ i ] );

}

}

public void start()

{

// create threads and start every time start is called

for ( int i = 0; i < threads.length; i++ ) 

{

threads[ i ] = new Thread( this, "Thread " + (i + 1) );

threads[ i ].start();

}

}

public void run()

{

Thread currentThread = Thread.currentThread();

int index = getIndex( currentThread );

char displayChar;

while ( threads[ index ] == currentThread ) 

{

// sleep from 0 to 1 second

try 

{

Thread.sleep( (int) ( Math.random() * 1000 ) );

synchronized( this ) 

{

while ( suspended[ index ] && threads[ index ] == currentThread )

wait();

}

}

catch ( InterruptedException e ) 

{

System.err.println( "sleep interrupted" );

}

displayChar = alphabet.charAt( (int) ( Math.random() * 26 ) );

outputs[ index ].setText( currentThread.getName() +

": " + displayChar );

}

System.err.println( currentThread.getName() + " terminating" );

}

private int getIndex( Thread current )

{

for ( int i = 0; i < threads.length; i++ )

if ( current == threads[ i ] )

return i;

return -1;

}

public synchronized void stop()

{

// stop threads every time stop is called

// as the user browses another Web page

for ( int i = 0; i < threads.length; i++ )

threads[ i ] = null;

notifyAll();

}

public synchronized void actionPerformed( ActionEvent e )

{

for ( int i = 0; i < checkboxes.length; i++ ) 

{

if ( e.getSource() == checkboxes[ i ] ) 

{

suspended[ i ] = !suspended[ i ];

outputs[ i ].setBackground( !suspended[ i ] ? Color.green : Color.red );

if ( !suspended[ i ] )

notify();

return;

}

}

}

 }

Horoscope

Description: This program allows the user to input a number and compute for the factorial of the number.

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

public class Factorial extends JFrame
     {
     private JTextField txtNum;
     private JLabel lblNum, lblRes;
     private JButton btnCompute;
  
     public static int ComputeFactorial(int number)
         {
         int n = number-1;
         do
             {
             number = number*n;
             n--;
         }while(n>=1);
         return number;
     }
  
     public Factorial()
         {
         super("GUI Factorial");
         Container c = getContentPane();
         c.setLayout(new FlowLayout());
         lblNum = new JLabel("Enter an integer: ");
         txtNum = new JTextField(10);
         lblRes = new JLabel();
         btnCompute = new JButton("Compute");
      
         btnCompute.addActionListener
         (
         new ActionListener()
             {
             public void actionPerformed(ActionEvent e)
                 {
                 String str = txtNum.getText();
                 int tmp = Integer.parseInt(str);
                 tmp = ComputeFactorial(tmp);
                 lblRes.setText("The factorial of "+str+" is "+tmp);
             }
         }
         );
        
         c.add(lblNum);
         c.add(txtNum);
         c.add(btnCompute);
         c.add(lblRes);
         setSize(200,150);
         show();
     }
  
     public static void main(String args[])
         {
         Factorial app = new Factorial();
         app.setResizable(false);
         app.setLocation(400,200);
         app.addWindowListener
         (
         new WindowAdapter()
             {
             public void windowClosing(WindowEvent e)
                 {
                 System.exit(0);
             }
         }
         );
     }
  
}

Calender of the current month

import java.util.*;

public class CalendarExample
     {
    
     public static void main(String []args)
         {
         //Construct new calendar
        
         GregorianCalendar d = new GregorianCalendar();
        
         int today = d.get(Calendar.DAY_OF_MONTH);
         int month = d.get(Calendar.MONTH);
        
         d.set(Calendar.DAY_OF_MONTH, 1);
        
         int weekday = d.get(Calendar.DAY_OF_WEEK);
        
         System.out.println("Sun Mon Tue Wed Thu Fri Sat");
        
         for (int i = Calendar.SUNDAY; i < weekday; i++)
         System.out.print(" ");
        
         do
             {
             int day = d.get(Calendar.DAY_OF_MONTH);
            
             if (day < 10) System.out.print(" ");
             System.out.print(day);
            
             if(day == today)
             System.out.print("* ");
             else
             System.out.print(" ");
            
             if (weekday == Calendar.SATURDAY)
             System.out.println();
            
             d.add(Calendar.DAY_OF_MONTH, 1);
             weekday = d.get(Calendar.DAY_OF_WEEK);
            
         }
        
         while (d.get(Calendar.MONTH) == month);
        
         if (weekday != Calendar.SUNDAY)
         System.out.println();
        
     }
}

Port Scanner

import java.net.*;
import java.io.IOException;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

    public class PScanner {
  
         public static void main(String[] args) {
         InetAddress ia=null;
         String host=null;
             try {
          
             host=JOptionPane.showInputDialog("Enter the Host name to scan:\n example: xxx.com");
                 if(host!=null){
                 ia = InetAddress.getByName(host);
             scan(ia); }
         }
             catch (UnknownHostException e) {
             System.err.println(e );
         }
         System.out.println("Bye from NFS");
         //System.exit(0);
     }
  
        public static void scan(final InetAddress remote) {
        //variables for menu bar
      
        int port=0;
        String hostname = remote.getHostName();
      
             for ( port = 0; port < 65536; port++) {
                 try {
                 Socket s = new Socket(remote,port);
                 System.out.println("Server is listening on port " + port+ " of " + hostname);
                 s.close();
             }
                 catch (IOException ex) {
                 // The remote host is not listening on this port
                 System.out.println("Server is not listening on port " + port+ " of " + hostname);
             }
         }//for ends
     }
}

Ping a server

import java.io.*;
import java.net.*;

     public class PseudoPing {
         public static void main(String args[]) {
             try {
             Socket t = new Socket(args[0], 7);
             DataInputStream dis = new DataInputStream(t.getInputStream());
             PrintStream ps = new PrintStream(t.getOutputStream());
             ps.println("Hello");
             String str = is.readLine();
             if (str.equals("Hello"))
             System.out.println("Alive!") ;
             else
             System.out.println("Dead or echo port not responding");
             t.close();
         }
             catch (IOException e) {
         e.printStackTrace();}
     }
}

Change look and feel

package com.ack.gui.swing.simple;

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.*;

public class ChangeLookAndFeel extends JFrame implements ActionListener {
  static String metalClassName = "javax.swing.plaf.metal.MetalLookAndFeel";
  static String motifClassName = "com.sun.java.swing.plaf.motif.MotifLookAndFeel";
  static String windowsClassName = "com.sun.java.swing.plaf.windows.WindowsLookAndFeel";

  public static void main( String[] argv ) {
    ChangeLookAndFeel myExample = new ChangeLookAndFeel( "Change Look And Feel" );
  }

  public ChangeLookAndFeel( String title ) {
    super( title );
    setSize( 150, 150 );
    addWindowListener( new WindowAdapter() {
      public void windowClosing( WindowEvent we ) {
        dispose();
        System.exit( 0 );
      }
    } );
    JPanel my_panel = new JPanel();
    my_panel.setLayout( new GridLayout( 1, 3 ) );
    JButton jb = new JButton( "Metal" );
    my_panel.add( jb );
    jb.addActionListener( this );
    jb = new JButton( "Motif" );
    my_panel.add( jb );
    jb.addActionListener( this );
    jb = new JButton( "Windows" );
    my_panel.add( jb );
    jb.addActionListener( this );
    getContentPane().add( my_panel );
    my_panel.setBorder( BorderFactory.createEtchedBorder() );
    pack();
    setVisible( true );
  }

  public void changeLookTo( String cName ) {
    try {
      UIManager.setLookAndFeel( cName );
    }
    catch( Exception e ) {
      System.out.println( "Could not change l&f" );
    }
    SwingUtilities.updateComponentTreeUI( this );
    this.pack();
  }

  public void actionPerformed( ActionEvent ae ) {
    String title = ae.getActionCommand();
    if( title.equals( "Metal" ) )
      changeLookTo( metalClassName );
    else if( title.equals( "Motif" ) )
      changeLookTo( motifClassName );
    else if( title.equals( "Windows" ) ) changeLookTo( windowsClassName );

  }
}

FingerPrint in Java

package com.ack.security.jce;

import java.io.FileInputStream;
import java.security.MessageDigest;
import javax.swing.*;

import sun.misc.BASE64Encoder;

/**
 * Builds the finger print of file, crypto hash value
 */
public class FingerPrint {
  public static void main(String[] args) throws Exception {
    // get the file path e.g. c:\Docs\zigzag.txt
    String inputText = JOptionPane.showInputDialog("Input your file path  ");

    // trying to build new message digest which represents and encapsulates
    // the Message Java Digest

    MessageDigest messageDigest = MessageDigest.getInstance("MD5");
    // calculating from the given file running its inside
    // while calculating the digest formula

    FileInputStream input = new FileInputStream(inputText);
    byte[] buffer = new byte[8192];
    int length;
    while( (length = input.read(buffer)) != -1 ) {
      messageDigest.update(buffer, 0, length);
    }
    byte[] raw = messageDigest.digest();

    //printout in 64 base
    BASE64Encoder encoder = new BASE64Encoder();
    String base64 = encoder.encode(raw);

    // and display the results
    JOptionPane.showMessageDialog(JOptionPane.getRootFrame(),
                                  "your file finger print is "
                                  + new String(base64.toString()));


  } // main method end

}  // class end

BlowfishCipher

package com.ack.security.jce;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.swing.JOptionPane;

/**
 * This program demonstrates how to encrypt/decrypt input
 * using the Blowfish Cipher with the Java Cryptograhpy.
 *
 */
public class BlowfishCipher {

  public static void main(String[] args) throws Exception {

    // create a key generator based upon the Blowfish cipher
    KeyGenerator keygenerator = KeyGenerator.getInstance("Blowfish");

    // create a key
    SecretKey secretkey = keygenerator.generateKey();

    // create a cipher based upon Blowfish
    Cipher cipher = Cipher.getInstance("Blowfish");

    // initialise cipher to with secret key
    cipher.init(Cipher.ENCRYPT_MODE, secretkey);

    // get the text to encrypt
    String inputText = JOptionPane.showInputDialog("Input your message: ");

    // encrypt message
    byte[] encrypted = cipher.doFinal(inputText.getBytes());

    // re-initialise the cipher to be in decrypt mode
    cipher.init(Cipher.DECRYPT_MODE, secretkey);

    // decrypt message
    byte[] decrypted = cipher.doFinal(encrypted);

    // and display the results
    JOptionPane.showMessageDialog(JOptionPane.getRootFrame(),
                                  "encrypted text: " + new String(encrypted) + "\n" +
                                  "decrypted text: " + new String(decrypted));

    // end example
    System.exit(0);
  }
}

Adding Items and Removing Itesm from JList

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

    public class PhilosophersJList extends JFrame {
  
     private DefaultListModel philosophers;
     private JList list;
  
     public PhilosophersJList()
         {
         super( "Favorite Philosophers" );
      
         // create a DefaultListModel to store philosophers
         philosophers = new DefaultListModel();
         philosophers.addElement( "Socrates" );
         philosophers.addElement( "Plato" );
         philosophers.addElement( "Aristotle" );
         philosophers.addElement( "St. Thomas Aquinas" );
         philosophers.addElement( "Soren Kierkegaard" );
         philosophers.addElement( "Immanuel Kant" );
         philosophers.addElement( "Friedrich Nietzsche" );
         philosophers.addElement( "Hannah Arendt" );
      
         // create a JList for philosophers DefaultListModel
         list = new JList( philosophers );
      
         // allow user to select only one philosopher at a time
         list.setSelectionMode(
         ListSelectionModel.SINGLE_SELECTION );
      
         // create JButton for adding philosophers
         JButton addButton = new JButton( "Add Philosopher" );
         addButton.addActionListener(
             new ActionListener() {
          
             public void actionPerformed( ActionEvent event )
                 {
                 // prompt user for new philosopher's name
                 String name = JOptionPane.showInputDialog(
                 PhilosophersJList.this, "Enter Name" );
              
                 // add new philosopher to model
                 philosophers.addElement( name );
             }
         }
         );
      
         // create JButton for removing selected philosopher
         JButton removeButton =
         new JButton( "Remove Selected Philosopher" );
      
         removeButton.addActionListener(
             new ActionListener() {
          
             public void actionPerformed( ActionEvent event )
                 {
                 // remove selected philosopher from model
                 philosophers.removeElement(
                 list.getSelectedValue() );
             }
         }
         );
      
         // lay out GUI components
         JPanel inputPanel = new JPanel();
         inputPanel.add( addButton );
         inputPanel.add( removeButton );
      
         Container container = getContentPane();
         container.add( list, BorderLayout.CENTER );
         container.add( inputPanel, BorderLayout.NORTH );
      
         setDefaultCloseOperation( EXIT_ON_CLOSE );
         setSize( 400, 300 );
         setVisible( true );
      
     } // end PhilosophersJList constructor
  
     // execute application
     public static void main( String args[] )
         {
         new PhilosophersJList();
     }
}

A scoping example

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

 public class Scoping extends JApplet
 {
JTextArea outputArea;
int x = 1; // instance variable

public void init()
{
outputArea = new JTextArea();
Container c = getContentPane();
c.add( outputArea );
}

public void start()
{
int x = 5; // variable local to method start

outputArea.append( "local x in start is " + x );

methodA(); // methodA has automatic local x
methodB(); // methodB uses instance variable x
methodA(); // methodA reinitializes automatic local x
methodB(); // instance variable x retains its value

outputArea.append( "\n\nlocal x in start is " + x );
}

public void methodA()
{
int x = 25; // initialized each time a is called

outputArea.append( "\n\nlocal x in methodA is " + x + " after entering methodA" );
++x;
outputArea.append( "\nlocal x in methodA is " + x + " before exiting methodA" );
}

public void methodB()
{
outputArea.append( "\n\ninstance variable x is " + x + " on entering methodB" );
x *= 10;
outputArea.append( "\ninstance variable x is " + x + " on exiting methodB" );
}
 }

Callable statement example

public class CallableStmt
    {
     public static void main(String args[])
         {
         try
             {
             Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
             Connection con = DriverManager.getConnection("jdbc:odbc:uma","kworker","kworker");
          
             //calling a stored procedure with no input/output param
             /*
             CREATE PROCEDURE HELLOWORLD
             AS
             SELECT 'HELLOWORLD' AS HELLO
             */
             CallableStatement cs1 = con.prepareCall("{call HelloWorld}");
             ResultSet rs1 = cs1.executeQuery();
             while(rs1.next())
                 {
                 String one = rs1.getString("HELLO");
                 System.out.println(one);
             }
          
          
             //Calling a stored procedure which takes in 2 parameters for addition
             /*
             --EXECUTE ADDITION 10,25,NULL
             ALTER PROCEDURE ADDITION
             @A INT
             , @B INT
             , @C INT OUT
             AS
             SELECT @C = @A + @B
             */
             CallableStatement cs2 = con.prepareCall("{call ADDITION(?,?,?)}");
             cs2.registerOutParameter(3,java.sql.Types.INTEGER);
             cs2.setInt(1,10);
             cs2.setInt(2,25);
             cs2.execute();
             int res = cs2.getInt(3);
             System.out.println(res);
          
             //Another way
             /*
             --create table test(slno int,ques varchar(100),ans text)
             --EXECUTE fetchRec 1
             create procedure fetchRec
             @A int
             as
             select * from test where slno=@A
             */
             CallableStatement cs3 = con.prepareCall("{call fetchRec(?)}");
             cs3.registerOutParameter(1,java.sql.Types.INTEGER);
             cs3.setInt(1,5);
             ResultSet rs3 = cs3.executeQuery();
             while(rs3.next())
                 {
                 String ques = rs3.getString(2);
                 String ans = rs3.getString(3);
                 System.out.println(ques);
                 System.out.println(ans);
             }
          
          
         }
         catch(Exception e)
             {
             e.printStackTrace();
         }
     }
}

TrayIconDemo

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

public class TrayIconDemo {
    public static void main(String[] args) {
        /* Use an appropriate Look and Feel */
        try {
          

UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFee

l");
            //UIManager.setLookAndFeel("javax.swing.plaf.metal.MetalLookAndFeel");
        } catch (UnsupportedLookAndFeelException ex) {
            ex.printStackTrace();
        } catch (IllegalAccessException ex) {
            ex.printStackTrace();
        } catch (InstantiationException ex) {
            ex.printStackTrace();
        } catch (ClassNotFoundException ex) {
            ex.printStackTrace();
        }
        /* Turn off metal's use of bold fonts */
        UIManager.put("swing.boldMetal", Boolean.FALSE);
        //Schedule a job for the event-dispatching thread:
        //adding TrayIcon.
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
    
    private static void createAndShowGUI() {
        //Check the SystemTray support
        if (!SystemTray.isSupported()) {
            System.out.println("SystemTray is not supported");
            return;
        }
        final PopupMenu popup = new PopupMenu();
        final TrayIcon trayIcon =
                new TrayIcon(createImage("images/bulb.gif", "tray icon"));
        final SystemTray tray = SystemTray.getSystemTray();
        
        // Create a popup menu components
        MenuItem aboutItem = new MenuItem("About");
        CheckboxMenuItem cb1 = new CheckboxMenuItem("Set auto size");
        CheckboxMenuItem cb2 = new CheckboxMenuItem("Set tooltip");
        Menu displayMenu = new Menu("Display");
        MenuItem errorItem = new MenuItem("Error");
        MenuItem warningItem = new MenuItem("Warning");
        MenuItem infoItem = new MenuItem("Info");
        MenuItem noneItem = new MenuItem("None");
        MenuItem exitItem = new MenuItem("Exit");
        
        //Add components to popup menu
        popup.add(aboutItem);
        popup.addSeparator();
        popup.add(cb1);
        popup.add(cb2);
        popup.addSeparator();
        popup.add(displayMenu);
        displayMenu.add(errorItem);
        displayMenu.add(warningItem);
        displayMenu.add(infoItem);
        displayMenu.add(noneItem);
        popup.add(exitItem);
        
        trayIcon.setPopupMenu(popup);
        
        try {
            tray.add(trayIcon);
        } catch (AWTException e) {
            System.out.println("TrayIcon could not be added.");
            return;
        }
        
        trayIcon.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                JOptionPane.showMessageDialog(null,
                        "This dialog box is run from System Tray");
            }
        });
        
        aboutItem.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                JOptionPane.showMessageDialog(null,
                        "This dialog box is run from the About menu item");
            }
        });
        
        cb1.addItemListener(new ItemListener() {
            public void itemStateChanged(ItemEvent e) {
                int cb1Id = e.getStateChange();
                if (cb1Id == ItemEvent.SELECTED){
                    trayIcon.setImageAutoSize(true);
                } else {
                    trayIcon.setImageAutoSize(false);
                }
            }
        });
        
        cb2.addItemListener(new ItemListener() {
            public void itemStateChanged(ItemEvent e) {
                int cb2Id = e.getStateChange();
                if (cb2Id == ItemEvent.SELECTED){
                    trayIcon.setToolTip("Sun TrayIcon");
                } else {
                    trayIcon.setToolTip(null);
                }
            }
        });
        
        ActionListener listener = new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                MenuItem item = (MenuItem)e.getSource();
                //TrayIcon.MessageType type = null;
                System.out.println(item.getLabel());
                if ("Error".equals(item.getLabel())) {
                    //type = TrayIcon.MessageType.ERROR;
                    trayIcon.displayMessage("Sun TrayIcon Demo",
                            "This is an error message", TrayIcon.MessageType.ERROR);
                    
                } else if ("Warning".equals(item.getLabel())) {
                    //type = TrayIcon.MessageType.WARNING;
                    trayIcon.displayMessage("Sun TrayIcon Demo",
                            "This is a warning message", TrayIcon.MessageType.WARNING);
                    
                } else if ("Info".equals(item.getLabel())) {
                    //type = TrayIcon.MessageType.INFO;
                    trayIcon.displayMessage("Sun TrayIcon Demo",
                            "This is an info message", TrayIcon.MessageType.INFO);
                    
                } else if ("None".equals(item.getLabel())) {
                    //type = TrayIcon.MessageType.NONE;
                    trayIcon.displayMessage("Sun TrayIcon Demo",
                            "This is an ordinary message", TrayIcon.MessageType.NONE);
                }
            }
        };
        
        errorItem.addActionListener(listener);
        warningItem.addActionListener(listener);
        infoItem.addActionListener(listener);
        noneItem.addActionListener(listener);
        
        exitItem.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                tray.remove(trayIcon);
                System.exit(0);
            }
        });
    }
    
    //Obtain the image URL
    protected static Image createImage(String path, String description) {
        URL imageURL = TrayIconDemo.class.getResource(path);
        
        if (imageURL == null) {
            System.err.println("Resource not found: " + path);
            return null;
        } else {
            return (new ImageIcon(imageURL, description)).getImage();
        }
    }
}

simple media player

import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
import java.lang.String;
import java.net.URL;
import java.net.MalformedURLException;
import java.io.IOException;
import java.util.Properties;
import javax.media.*;
//import com.sun.media.util.JMFSecurity;

/**
  * This is a Java Applet that demonstrates how to create a simple
  * media player with a media event listener. It will play the
  * media clip right away and continuously loop.
  *
  *<!-- Sample HTML
  * <applet code=SimplePlayerApplet width=320  0>
  * <param name=file value="sun.avi">
  * </applet>
  * -->
  */
public class SimplePlayerApplet extends Applet implements ControllerListener {
  
    // media Player
    Player player = null;
    // component in which video is playing
    Component visualComponent = null;
    // controls gain, position, start, stop
    Component controlComponent = null;
    // displays progress during download
    Component progressBar = null;
    boolean firstTime = true;
    long CachingSize = 0L;  
    Panel panel = null;
    int controlPanelHeight = 0;
    int videoWidth = 0;
    int videoHeight = 0;

    /**
     * Read the applet file parameter and create the media
     * player.
     */
    public void init() {
        //$ System.out.println("Applet.init() is called");
        setLayout(null);
        setBackground(Color.white);
        panel = new Panel();
        panel.setLayout( null );
        add(panel);
        panel.setBounds(0, 0, 320, 240);

        // input file name from html param
        String mediaFile = null;
        // URL for our media file
        MediaLocator mrl = null;
        URL url = null;

        // Get the media filename info.
        // The applet tag should contain the path to the
        // source media file, relative to the html page.
      
        if ((mediaFile = getParameter("FILE")) == null)
            Fatal("Invalid media file parameter");

        try {
            url = new URL(getDocumentBase(), mediaFile);
            mediaFile = url.toExternalForm();
        } catch (MalformedURLException mue) {
        }
      
        try {
            // Create a media locator from the file name
            if ((mrl = new MediaLocator(mediaFile)) == null)
                Fatal("Can't build URL for " + mediaFile);

            /*
            try {
                JMFSecurity.enablePrivilege.invoke(JMFSecurity.privilegeManager,
                                                   JMFSecurity.writePropArgs);
                JMFSecurity.enablePrivilege.invoke(JMFSecurity.privilegeManager,
                                                   JMFSecurity.readPropArgs);
                JMFSecurity.enablePrivilege.invoke(JMFSecurity.privilegeManager,
                                                   JMFSecurity.connectArgs);
            } catch (Exception e) {}
            */
          
            // Create an instance of a player for this media
            try {
                player = Manager.createPlayer(mrl);
            } catch (NoPlayerException e) {
                System.out.println(e);
                Fatal("Could not create player for " + mrl);
            }

            // Add ourselves as a listener for a player's events
            player.addControllerListener(this);

        } catch (MalformedURLException e) {
            Fatal("Invalid media file URL!");
        } catch (IOException e) {
            Fatal("IO exception creating player for " + mrl);
        }

        // This applet assumes that its start() calls
        // player.start(). This causes the player to become
        // realized. Once realized, the applet will get
        // the visual and control panel components and add
        // them to the Applet. These components are not added
        // during init() because they are long operations that
        // would make us appear unresposive to the user.
    }

    /**
     * Start media file playback. This function is called the
     * first time that the Applet runs and every
     * time the user re-enters the page.
     */

    public void start() {
        //$ System.out.println("Applet.start() is called");
        // Call start() to prefetch and start the player.
        if (player != null)
            player.start();
    }

    /**
     * Stop media file playback and release resource before
     * leaving the page.
     */
    public void stop() {
        //$ System.out.println("Applet.stop() is called");
        if (player != null) {
            player.stop();
            player.deallocate();
        }
    }

    public void destroy() {
        //$ System.out.println("Applet.destroy() is called");
        player.close();
    }


    /**
     * This controllerUpdate function must be defined in order to
     * implement a ControllerListener interface. This
     * function will be called whenever there is a media event
     */
    public synchronized void controllerUpdate(ControllerEvent event) {
        // If we're getting messages from a dead player,
        // just leave
        if (player == null)
            return;
      
        // When the player is Realized, get the visual
        // and control components and add them to the Applet
        if (event instanceof RealizeCompleteEvent) {
            if (progressBar != null) {
                panel.remove(progressBar);
                progressBar = null;
            }

            int width = 320;
            int height = 0;
            if (controlComponent == null)
                if (( controlComponent =
                      player.getControlPanelComponent()) != null) {
                  
                    controlPanelHeight = controlComponent.getPreferredSize().height;
                    panel.add(controlComponent);
                    height += controlPanelHeight;
                }
            if (visualComponent == null)
                if (( visualComponent =
                      player.getVisualComponent())!= null) {
                    panel.add(visualComponent);
                    Dimension videoSize = visualComponent.getPreferredSize();
                    videoWidth = videoSize.width;
                    videoHeight = videoSize.height;
                    width = videoWidth;
                    height += videoHeight;
                    visualComponent.setBounds(0, 0, videoWidth, videoHeight);
                }

            panel.setBounds(0, 0, width, height);
            if (controlComponent != null) {
                controlComponent.setBounds(0, videoHeight,
                                           width, controlPanelHeight);
                controlComponent.invalidate();
            }
          
        } else if (event instanceof CachingControlEvent) {
            if (player.getState() > Controller.Realizing)
                return;
            // Put a progress bar up when downloading starts,
            // take it down when downloading ends.
            CachingControlEvent e = (CachingControlEvent) event;
            CachingControl cc = e.getCachingControl();

            // Add the bar if not already there ...
            if (progressBar == null) {
                if ((progressBar = cc.getControlComponent()) != null) {
                    panel.add(progressBar);
                    panel.setSize(progressBar.getPreferredSize());
                    validate();
                }
            }
        } else if (event instanceof EndOfMediaEvent) {
            // We've reached the end of the media; rewind and
            // start over
            player.setMediaTime(new Time(0));
            player.start();
        } else if (event instanceof ControllerErrorEvent) {
            // Tell TypicalPlayerApplet.start() to call it a day
            player = null;
            Fatal(((ControllerErrorEvent)event).getMessage());
        } else if (event instanceof ControllerClosedEvent) {
            panel.removeAll();
        }
    }

    void Fatal (String s) {
        // Applications will make various choices about what
        // to do here. We print a message
        System.err.println("FATAL ERROR: " + s);
        throw new Error(s); // Invoke the uncaught exception
                            // handler System.exit() is another
                            // choice.
      
    }
}