1    /* 
2    A program that explores some elementary concepts of array lists. 
3     */
4    
5    package arraylistplay;
6    
7    import java.util.ArrayList;
8    
9    public class Primes {
10   
11       public static void main(String[] args) {
12           ArrayList<Integer> primes = new ArrayList<>();
13   
14           primes.add(2);
15           primes.add(3);
16           primes.add(5);
17           primes.add(7);
18   
19           System.out.println("size of primes list = "+primes.size());
20           System.out.println("first prime = "+primes.get(0));
21           System.out.println("last primes = "+primes.get(3));
22           System.out.println("last prime ="+primes.get(primes.size()-1));
23   
24           System.out.println("\nThe initial list ...");
25           for (Integer prime : primes) {
26               System.out.println(prime);
27           }
28   
29           int temp = primes.get(0);
30           primes.set(0, primes.get(primes.size()-1));
31           primes.set(primes.size()-1, temp);
32   
33           System.out.println("\nThe final list ...");
34           for (Integer prime : primes ) {
35               System.out.println(prime);
36           }
37       }
38   }
39