Google wanted Android to be accessible to developers familiar with Java. Accordingly, although Google purchased or rewrote from scratch all the code that provides the functionality of Android, it ...

Android in 2006 Version 0.91 of the Google's project definition for Android, completed July 6, 2006, was not an open document. It is labeled "Google Proprietary" and "Highly Confidential." ...

As Android prospered, Oracle's Java licensing business, centered largely around feature-phones, cratered. "They copied 11,500 lines of code," Oracle attorney Peter Bicks said during closing arguments.

In this Java 101 tutorial, I’ve explained how interfaces differ from classes, and showed you how to declare, implement, and extend interfaces in your Java programs.