Java How to Program, Early Objects, 11th Edition

... Eratosthenes, using a BitSet.

 1   // Fig. K.10: BitSetTest.java
 2   // Using a BitSet to demonstrate the Sieve of Eratosthenes.
 3   import java.util.BitSet;
 4   import java.util.Scanner;
 5
 6   public class BitSetTest {
 7      public static void main(String[] args) {
 8         // get input integer
 9         Scanner scanner = new Scanner(System.in);
10         System.out.println("Please enter an integer from 2 to 1023");
11         int input = scanner.nextInt();
12
13         // perform Sieve of Eratosthenes 
14         BitSet sieve = new BitSet(1024); 
15         int size = sieve.size();         
16
17         // set all bits from 2 to 1023
18         for (int i = 2; i < size; i++) {
19            sieve.set(i);
20         } 
21
22         // perform Sieve of Eratosthenes
23         int finalBit = (int) Math.sqrt(size); 
24
25         for (int i = 2; i < finalBit; i++) { 
26            if (sieve.get(i) ...