If you want to build an Android app you can install the software development kit on your computer and then test your apps in an emulator or export them to an Android device — or you can just fire up a new app called AIDE that lets you program Android apps on an Android device. Then you can go ahead and test them on the very same device.
AIDE stands for Android Integrated Development Environment, and it basically provides all the tools you need to create an Android application. It’s also compatible with Eclipse projects, so you can start a project on your PC and then copy the source code to your mobile device to continue working on it.
While an Android smartphone might not be the ideal device for writing code, the developers behind AIDE have been testing the software with an Asus Eee Transformer Prime tablet which has a keyboard dock and a speedy processor. But the app should work on most phones and tablets running Android 2.2 or later.
AIDE is available as a free download from the Android Market.