1    /* 
2     * A program to understand the arraylist methods 
3     */
4    package arraylistplay;
5    
6    import java.util.ArrayList;
7    
8    public class Primes {
9        public static void main (String[] args){
10           ArrayList<Integer> primes = new ArrayList<>();
11   
12           primes.add(2);
13           primes.add(3);
14           primes.add(5);
15           primes.add(7);
16   
17           System.out.println("length 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 array...");
23           int i = 0;
24           while (i<primes.size()){
25               System.out.println(primes.get(i));
26               i = i + 1;
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 array...");
34           for (Integer prime : primes){
35               System.out.println(prime);
36           }
37           
38       }
39   }
40