On May 14, 2012, at 1:12 PM, Jones wrote:
> SimpleExpandableListAdapter isn't working. I'm just getting the error message
> from the log that there is a cast exception.
Can you provide the SimpleExpandableListAdapter use?
As a guess, try replacing Dictionary use with JavaDictionary:
// Old:
IList<IDictionary<string, object>> groupData = new
List<IDictionary<string, object>>() {
new Dictionary<string, object> { ... },
};
new SimpleExpandableListAdapter (this, groupData, ...);
// New:
IList<IDictionary<string, object>> groupData = new
List<IDictionary<string, object>>() {
new JavaDictionary<string, object> { ... },
};
My suspicion is that the change is due to fixing:
https://bugzilla.xamarin.com/show_bug.cgi?id=2147
That is, if you pass a non-Java.Lang.Object subclass to Java code, it'll get
"wrapped" into a JavaObject (internal type), and when it comes back out from
Java it'll be "unwrapped", thus providing reference equality: what you put in
is what you get out.
Unfortunately this is a break from the previous behavior, which would try to
"deep marshal" the collection types, which allowed things to work but meant
that if you later queried for the "original" List/Dictionary/etc. you'd get
back a completely different instance (object.ReferenceEquals() would be false).
For those who are concerned about gref counts, an alternative coding pattern is:
using (IList<IDictionary<string, object>> groupData = new
JavaList<IDictionary<string, object>>()) {
using (var d = new JavaDictionary<string, object> { ... })
groupData.Add (d);
new SimpleExpandableListAdapter (this, groupData, ...);
}
The above ensures that the JavaDictionary and JavaList instances don't survive
past the SimpleExpandableListAdapter use, whereas previously the grefs would
stick around ~forever (or until the SimpleExpandableListAdapter instance was no
longer used in both Java & C#).
- Jon
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