Case of Missing Runtime Error

Question

I have this program when I have initialized with a generic type of Integer but not declared it with a generic type of Integer , when I try to add a String I don't get a compile error as expected , but I don't even get a runtime error when I run , what do you think is happening here ?
//Declaration with no ArrayList<Integer> al
ArrayList al = new ArrayList<Integer>();
al.add(45);
al.add("This string should not be here");
try
for (Iterator<Integer> i = al.iterator();i.hasNext();)
System.out.println("al[" + i + "]:" + i.next());
} catch (Exception e)
System.out.println("Message:" + e.getMessage());
}

Answer 1

Well there's nothing there that tries to cast a list element to an Integer. This would throw a ClassCastException:
for (Integer integer : al)
     System.out.println(integer.toString());
}