// Fig. 23.13: BitSetTest.java                                
// Using a BitSet to demonstrate the Sieve of Eratosthenes.
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;

public class BitSetTest extends JFrame {
 
   public BitSetTest()
   {
      super( "BitSets" );

      final BitSet sieve = new BitSet( 1024 );
      Container c = getContentPane();
      final JLabel status = new JLabel();
      c.add( status, BorderLayout.SOUTH );
      JPanel inputPanel = new JPanel();

      inputPanel.add( new JLabel( "Enter a value from " +
                                  "1 to 1023" ) );
      final JTextField input = new JTextField( 10 );
      input.addActionListener(
         new ActionListener() {
            public void actionPerformed( ActionEvent e )
            {
               int val = Integer.parseInt( input.getText() );

               if ( sieve.get( val ) )
                  status.setText( val + " is a prime number" );
               else
                  status.setText( val +
                                  " is not a prime number" );
            }
         }
      );
      inputPanel.add( input );
      c.add( inputPanel, BorderLayout.NORTH );

      JTextArea primes = new JTextArea();
      ScrollPane p = new ScrollPane();
      p.add( primes );

      c.add( p, BorderLayout.CENTER );

      // set all bits from 1 to 1023
      int size = sieve.size();

      for ( int i = 1; i < size; i++ )
         sieve.set( i );

      // perform Sieve of Eratosthenes
      int finalBit = ( int ) Math.sqrt( sieve.size() );

      for ( int i = 2; i < finalBit; i++ ) 
         if ( sieve.get( i ) ) 
            for ( int j = 2 * i; j < size; j += i ) 
               sieve.clear( j );

      int counter = 0;

      for ( int i = 1; i < size; i++ )
         if ( sieve.get( i ) ) {
            primes.append( String.valueOf( i ) );
            primes.append( ++counter % 7 == 0 ? "\n" : "\t" );
         }

      setSize( 300, 250 );
      show();
   }

   public static void main( String args[] )
   {
      BitSetTest app = new BitSetTest();
      app.addWindowListener(
         new WindowAdapter() {
            public void windowClosing( WindowEvent e )
            {
               System.exit( 0 );
            }
         }
      );
   }
}

/**************************************************************************
 * (C) Copyright 1999 by Deitel & Associates, Inc. and Prentice Hall.     *
 * All Rights Reserved.                                                   *
 *                                                                        *
 * DISCLAIMER: The authors and publisher of this book have used their     *
 * best efforts in preparing the book. These efforts include the          *
 * development, research, and testing of the theories and programs        *
 * to determine their effectiveness. The authors and publisher make       *
 * no warranty of any kind, expressed or implied, with regard to these    *
 * programs or to the documentation contained in these books. The authors *
 * and publisher shall not be liable in any event for incidental or       *
 * consequential damages in connection with, or arising out of, the       *
 * furnishing, performance, or use of these programs.                     *
 *************************************************************************/