The Auth0 Java Sample Code by Auth0 demonstrates how to authenticate a user on the web. Along with a downloadable seed project, resources present how to add dependencies, configure, and access user information.
Dashlane and Google have (finally!) brought their OpenYOLO password manager to Android. The basic idea is to improve app adoption by smoothing over the login process. Developers can grab the code from GitHub and integrate the You Only Login Once tool with their mobile apps.
User authentication in apps is a pain, even if you've built an authentication system dozens of times. Forms, sessions, user tables, validation, password management, the list goes on in the seemingly never-ending to-do list for setting up a simple signup, login, and logout system for your app. OpenID company Janrain makes it easier, building on top of social networks.