If you truly need to share objects among your app's activities, you can do it by subclassing Application. There is one instance of Application and it gets initialized before any activities start and sticks around for the life of all activities in your app.
If you can find another way to pass info, such as passing a file name or database primary key, that would be better.
Note that Application is only available to your activities. So, it won't help if you are trying to pass info to another app.