I'm using Hawk as a replacement for SharedPreferences
in my application.
I'm trying to store a LinkedHashMap
in it, but for some reason when I pull it back from Hawk it returns as a regular HashMap
and not a LinkedHashMap
. At this point I crash with a ClassCastException
as HashMap
can't be casted to LinkedHashMap
straight forward.
So the question is how can I convert the returned HashMap
to be a LinkedHashMap
?
All the answers suggesting that you can create a LinkedHashMap
from a HashMap
are technically correct, but will not give you the desired results :-(
Of course, you can create a LinkedHashMap
from a HashMap
, but it isn't guaranteed that the LinkedHashMap
will have the same order that your original did.
The problem is that your LinkedHashMap
is serialized when it is stored into the persistent storage as a plain unordered Map
, which does NOT persist the ordering of the individual items. When you then extract the object from the persistent storage, it is returned as a plain HashMap
, and it has lost the "ordering" (which is what you wanted a LinkedHashMap
for in the first place). If you then create a LinkedHashMap
from the returned HashMap
, the ordering will most probably be different from the original.
In order to do this correctly, you should probably convert your LinkedHashMap
into an ordered array of objects and store this ordered array in the persistent storage. You can then read the ordered array of objects back from the persistent storage and recreate the LinkedHashMap
with the correct order. Basically, you need to serialize and deserialize the LinkedHashMap
yourself.
See my answer to this question for more details.