Question regarding Generics

[Garg Amit]

Please explain.

Source:-http://www.javabeat.net/javabeat/scjp5/mocks/Generics-part2-7questions.php

   Which call(s) to method(addandDisp) are error free?
public static <T> void addandDisp(Collection<T> cs, T t)
{
	for (T o : cs)
	{
		s.add(o);
	}
	for (T o : cs)
	{
		System.out.println(o);
	}
}

//call 1
List<? super Object> ls1 = new LinkedList<Object>();
addandDisp(ls1,new String());

//call 2
List<? extends Object> ls2 = new LinkedList<Object>();
addandDisp(ls2,new Object());

//call 3
List<Object> ls3 = new LinkedList<Object>();
addandDisp(ls3,new String());

//call 4
List<? super Object> ls4 = new LinkedList<Object>();
addandDisp(ls4,new Object());
   
 

[Henry Wong]

It may be a good idea to search the forums -- as this question has been asked many times. See search link above.

Henry