Java How to Program Fourth Edition - DCC

1192 Java Utilities Package and Bit Manipulation Chapter 20
33
34 // textfield for user to input a value from 2 to 1023
35 inputField = new JTextField( 10 );
36
37 inputField.addActionListener(
38
39 new ActionListener() {
40
41 // determine whether value is prime number
42 public void actionPerformed( ActionEvent event )
43 {
44 int value = Integer.parseInt( inputField.getText() );
45
46 if ( sieve.get( value ) )
47 statusLabel.setText(
48 value + " is a prime number" );
49
50 else
51 statusLabel.setText( value +
52 " is not a prime number" );
53 }
54 }
55 );
56
57 inputPanel.add( inputField );
58 container.add( inputPanel, BorderLayout.NORTH );
59
60 JTextArea primesArea = new JTextArea();
61
62 container.add( new JScrollPane( primesArea ),
63 BorderLayout.CENTER );
64
65 // set all bits from 1 to 1023
66 int size = sieve.size();
67
68 for ( int i = 2; i < size; i++ )
69 sieve.set( i );
70
71 // perform Sieve of Eratosthenes
72 int finalBit = ( int ) Math.sqrt( sieve.size() );
73
74 for ( int i = 2; i < finalBit; i++ )
75
76 if ( sieve.get( i ) )
77
78 for ( int j = 2 * i; j < size; j += i )
79 sieve.clear( j );
80
81 // display prime numbers from 1 to 1023
82 int counter = 0;
83
Fig. Fig. 20.13 20.13 20.13 Demonstrating the Sieve of Eratosthenes using a BitSet (part 2 of 3).