Index: TreeMap.java =================================================================== --- TreeMap.java (revision 424216) +++ TreeMap.java (working copy) @@ -76,7 +76,11 @@ @SuppressWarnings("unchecked") private static Comparable toComparable(T obj) { - return (Comparable)obj; + try{ + return (Comparable)obj; + }catch(ClassCastException e){ + return null; + } } private static class AbstractMapIterator {