Annotations Question

Question

I came across this question in mock SCJP exam.
interface A
    void x();
class B implements A
   public void x()
    public void y()
class C extends B
   public void x()
And :
java.itl;List<A> list=new java.util.ArrayList<A>(); //LINE 20
list.add(new B());                   //LINE 21
list.add(new C());
for(A a:list)            // LINE 23
   a.>(),
   a.>()                //LINE 25
What is the result
A. THe code runs with no output
B. An exception is thrown as runtime.
C. Compilation fails because of an error in line 20.
D. Compilation fails because of an error in line 21.
E. Compilation fails because of an error in line 23.
F. Compilation fails because of an error in line 25.
ANSWER : FI am totally clueless about this question.Can anyone let me know where i can find pointer to this example ?
Thanks in Advance.

Answer 1

sunjava84 wrote:
I didn't get lines 20,23 and 25.
java.util;List<A> list=new java.util.ArrayList<A>(); //LINE 20What don't you get about line 20? The "<A>"? Generics were introduced in 1.5. Perhaps you only know an old version of Java.
[http://java.sun.com/docs/books/tutorial/extra/generics/index.html]
[http://java.sun.com/docs/books/tutorial/collections/index.html]
for(A a:list)            // LINE 23[The for-each loop|http://java.sun.com/j2se/1.5.0/docs/guide/language/foreach.html] was also introduced in 1.5
   a.>()                //LINE 25That line is garbled. I think they meant to simply call a method, like:
a.clear();By the way, [annotations |http://java.sun.com/j2se/1.5.0/docs/guide/language/annotations.html] were also introduced in 1.5, but they don't appear in this example.