I'm not much of a Java guy, but would the available source for KeePassDroid be of any use? It looks like most of the DB stuff was implemented in Java with the crypto bits being handled by the NDK.

KeePass is a free open source password manager, which helps you to manage your passwords in a secure way. You can put all your passwords in one database, which is ...

1Password and KeePass, but there is hardly any software that allows you to host the service yourself and share the password within the group. By using the basic free open source software 'Passbolt', ...