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