Libraries aren’t just for checking out books. They’re probably the most important part of any programming endeavor. With a good set of libraries, you don’t need to reinvent the wheel on every project. We rounded up five of the best libraries out there for everything from Web development to cloud development.

Libcloud

When building an application that will live in the cloud, you’ve got two choices: Either write to the native APIs of the cloud and lock yourself into that hosting provider forever, or use Libcloud. This project, which came out of the now-acquired CloudKick, is now under the watchful eye of the Apache Foundation. Libcloud offers link-ins to 24 different cloud hosting providers.

Rather than write specific code to handle the process of spinning up an Amazon Web Services image via Amazon’s own API, you can use Libcloud to set generic paths to such services. Instead of writing directly to Amazon’s load-balancing API, Libcloud allows developers to write more generic code for load balancing behavior, and the resulting code will trigger Amazon’s API. Or Rackspace’s API. Or GoGrid’s API. Or… you get the idea.

Guava-Libraries

Formerly known as the Google Collections Library, the Guava-Libraries is a collection of useful code that started out at Kevin Bourrillion’s 20% project at Google. I’ll let him explain the Guava-Libraries in his own words:

The same basic problems that the Java Collections Framework solves, just taken to the next level. Additional abstractions to more closely fit your needs; new data structures that speed up your processing; conveniences that wage war on boilerplate code everywhere. [Jared Levy, co-creator of Guava-Libraries] and I both love to play board games and, when there’s a board game that’s successful, the publisher inevitably comes back and releases an “expansion” for that game. With the expansion, you can still play the original game you already love, but you can do a little more as well: sail over to the neighboring islands, or go build your train lines in Switzerland instead, etc. So we’d love for you to see our library as “the unofficial expansion to the Java Collections Framework.”

Whether you feel we do or don’t measure up to that standard, it’s the mindset we have had since the beginning. We find the gaps in java.util and we fill those in; we pick up where the JDK leaves off. Most importantly, we conform to the principles and design choices in the Java Collections as much as possible, only deviating when there’s a very clear win.”

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