If you are a Java programmer actively involved in building apps for the Android operating system, it is most likely that you make use of the Android Software Development Kit (SDK). You should know though, that it's not your only option for a development environment. In just the past couple of years, a number of third-party development kits have become available that could be of use to you.
If you look hard enough, you can find a free, open source IDE for Android development, but in order to have full functionality, you're going to have to spend a few bucks. If you are just starting out in app development, and need to lower your expenses, here are some SDK alternatives that are more affordable.
Third-Party Development Kits
Inspired by Microsoft Visual Basic, one of the first object-oriented Web development tools with objects that could be seen, clicked, or dragged and dropped, Basic4android is the ideal tool for standard Visual Basic programmers who are having trouble programming with Java. This is a popular development tool and there is a very active online community of Basic4android developers who work together to help each other.
Google's entry into the SDK market came in 2010, with App Inventor for Android. This is an incredibly powerful Web-based visual development tool. Google released the source code in 2011, and it is now being maintained by the Massachusetts Institute of Technology (MIT).
If you search the Internet hard enough, you can find a free open source version of this tool, but you are best served getting it directly from MIT to make sure that you always get the most updated version.
A Free Open Source Android Tool
One of the few free Android development kits you will find is IntelliJ IDEA, a free open source IDE for Android developers. It features support for intelligent coding assistance, as well as a community of developers on the Internet that can offer help. IntelliJ IDEA can be downloaded directly from the Internet for free, and it comes with a tutorial to get novices started.
Some of the tool's top features include a powerful code editor, a code analyzer that works on the fly, and built-in Android tools and features that include drop and drag support, as well as a runner and debugger for emulators and actual devices.
IntelliJ IDEA also has a number of out-of-the-box features such as tasks and content management, VCS tools, and support for Gradle and Maven. Like most of the other open source, so-called free development tools out there for Android, it also offers an option to purchase the complete package. If you are a serious developer, that is the route to go.
You will find this, along with other open source tools out there for developers of all types, is prone to have bugs and can cause you and your computer problems. But if you're looking for a free Android development kit, this is one of your best options.