I mostly get the new variance ideas, but I've come across a case that won't compile and I don't understand why:

    // Array test
    Object[=] array1 = new Object[5];
    Integer[=] array2 = new Integer[5];
    array1 [0] = new Integer(1);
    array2 [0] = new Integer(2);
    Integer[-] array3;
    array3 = array1;
    array3 = array2;
    array3 [0] = new Integer(3);
 
    // This is the List equivalent?
    List<=Object> list1 = new ArrayList<Object>();
    List<=Integer> list2 = new ArrayList<Integer>();
    list1.add (new Integer(1));
    list2.add (new Integer(2));
    List<-Integer> list3;
    list3 = list1;
    list3 = list2;
    list3.add (new Integer (3));

The first half (dealing with arrays) all compiles fine. However, I get a compile error on the very last line:

Reference to add is ambiguous, both method add(E) in java.util.Collection<=-java.lang.Integer> and method add(E) in java.util.List<-java.lang.Integer> match

I don't understand this - is it a bug in the supplied libraries or do not I not understand contravariance properly?

 

 

Looks like a bug in the compiler. Reported as 4872698.