The android Bitcoin Wallet application stores data using androids MODE_PRIVATE in the following location:
It is worth noting that this is not compatible with your standard wallet.dat file from bitcoin-qt but may be compatible with other bitcoinj clients that support protobuf formats.
Some actions in the app cause a backup file to be created in up to two locations. The first is a key backup at:
The second is the external backup feature which is stored on the SD card at the following location:
Here is the link to detailed specs of the Android bitcoin wallet