You put T in, you get T out.

I'm open to suggestions as to whether this is the right thing.

I think if it were returning a view, we'd definitely want it like this.
You don't want a List<Integer> to look like a List<Number> and have
it break something when someone stuffs a Float in it.

But the argument could be made that returning a new List can surely be
seen as a List<Number> because it is not referenced anywhere else as
something more specific. Many of the guava methods allow a "re-typing"
like this, although I think they have admitted that it was a mistake and
newly added methods don't allow it.

In any case, I think that it's most proper to retain things as specifically
as possible. Why would you turn a List<Integer> into a List<Number>?
Why would you want to throw away the information? If you need to pass it
to a method that expects List<Number> then that method should be modified
to correctly accept List<? extends Number>.


git-svn-id: https://samskivert.googlecode.com/svn/trunk@2958 6335cc39-0255-0410-8fd6-9bcaacd3b74c

src/main/java/com/samskivert/util/CollectionUtil.java

@@ -135,7 +135,7 @@ public class CollectionUtil
      *
      * @throws NoSuchElementException if the Iterable is empty.
      */
-    public static <T extends Comparable<? super T>> List<T> maxList (Iterable<? extends T> iterable)
+    public static <T extends Comparable<? super T>> List<T> maxList (Iterable<T> iterable)
     {
         return maxList(iterable, new Comparator<T>() {
             public int compare (T o1, T o2) {
@@ -150,9 +150,9 @@ public class CollectionUtil
      *
      * @throws NoSuchElementException if the Iterable is empty.
      */
-    public static <T> List<T> maxList (Iterable<? extends T> iterable, Comparator<? super T> comp)
+    public static <T> List<T> maxList (Iterable<T> iterable, Comparator<? super T> comp)
     {
-        Iterator<? extends T> itr = iterable.iterator();
+        Iterator<T> itr = iterable.iterator();
         T max = itr.next();
         List<T> maxes = new ArrayList<T>();
         maxes.add(max);
@@ -186,7 +186,7 @@ public class CollectionUtil
      *
      * @throws NoSuchElementException if the Iterable is empty.
      */
-    public static <T extends Comparable<? super T>> List<T> minList (Iterable<? extends T> iterable)
+    public static <T extends Comparable<? super T>> List<T> minList (Iterable<T> iterable)
     {
         return maxList(iterable, java.util.Collections.reverseOrder());
     }
@@ -197,7 +197,7 @@ public class CollectionUtil
      *
      * @throws NoSuchElementException if the Iterable is empty.
      */
-    public static <T> List<T> minList (Iterable<? extends T> iterable, Comparator<? super T> comp)
+    public static <T> List<T> minList (Iterable<T> iterable, Comparator<? super T> comp)
     {
         return maxList(iterable, java.util.Collections.reverseOrder(comp));
     }