Android APIs
Added in API level 1
package

javax.security.auth.callback

This package provides classes and interfaces needed to interact with the application in order to execute the authentication and authorization processes. It is a classical callback mechanism: one retrieves information (i.e. for authentication purposes) and one display some messages (for example error messages).

Note that the current implementation of this package is not complete, that is, not compatible with desktop implementations of the Java programming language. It contains only what was needed to make the compiler happy, that is, classes required by other packages.

Interfaces

Callback Defines an empty base interface for all Callbacks used during authentication. 
CallbackHandler Needs to be implemented by classes that want to handle authentication Callbacks. 

Classes

PasswordCallback Used in conjunction with a CallbackHandler to retrieve a password when needed. 

Exceptions

UnsupportedCallbackException Thrown when a CallbackHandler does not support a particular Callback