UnsafeDemo2.java.html

  1  import java.util.ArrayList;
  2  import java.util.Iterator;
  3  
  4  public class UnsafeDemo2
  5  {
  6     public static void main(String[] args)
  7     {
  8        ArrayList<Integer> numbers = new ArrayList<Integer>();
  9        numbers.add(1);
 10        numbers.add(2);
 11        numbers.add(3);
 12        print(numbers);
 13        System.out.println("Sum: " + sum(numbers));
 14        numbers.add("4"); // Compiler error message
 15        print(numbers); 
 16        System.out.println("Sum: " + sum(numbers));
 17     }
 18  
 19     public static void print(ArrayList<Integer> lst)
 20     {
 21        Iterator<Integer> iter = lst.iterator();
 22        while (iter.hasNext())
 23        {
 24           System.out.print(iter.next() + " ");
 25        }
 26        System.out.println();
 27     }
 28  
 29     public static int sum(ArrayList<Integer> lst)
 30     {
 31        int sum = 0;
 32        Iterator<Integer> iter = lst.iterator();
 33        while (iter.hasNext())
 34        {
 35           sum = sum + iter.next(); // No cast needed
 36        }
 37        return sum;
 38     }
 39  }