You do not need to use Eclipse, it is highly recommended because the tools are well integrated:
The recommended development method for an Android application is to use Eclipse with the ADT plugin. The ADT plugin provides editing, creation, debugging, and .apk packaging and signing functionality integrated into the IDE.
However, if you prefer applications in another IDE, such as IntelliJ, or in a base editor, such as Emacs, you can do this. The SDK includes all the tools necessary to set up an Android project, create it, debug it, and then distribute it. This document is your guide to using these tools.
See this page in the Dev manual for more information: Development in other IDEs