yes google code is a wonderful place for source code to learn from. Google Developers (previously Google Code) is Google's site for software development tools and platforms, application programming interfaces (APIs), and technical resources. The site contains documentation on using Google developer tools and APIs—including discussion groups and blogs for developers using Google's developer products.There are APIs offered for almost all of Google's popular consumer products, like Google Maps, YouTube, Google Apps, and others.
The site also features a variety of developer products and tools built specifically for developers. Google App Engine is a hosting service for web apps. Project Hosting gives users version control for open source code. Google Web Toolkit (GWT) allows developers to create Ajax applications in the Java programming language.(All languages)
The site contains reference information for community based developer products that Google is involved with like Android from the Open Handset Alliance and OpenSocial from the OpenSocial Foundation.