This is a tool for onboard android programming. For this tool works you should install JavaIDEDroid program for compile your Java program and OI FileManager for choose program files.
JavaIDEDroid use bsh scripts for programs compilation. On the DroidDevelop you can choose bsh script for compilation by "Open Project..." command. For compile you should press compile button.
You also can install and your run programm without exit from DroidDevelop. For this purpose you can press "Run..." button.
You also can edit your java or another project files without exit from DroidDevelop.
In Pro version avail syntax highlighting.
Android Market Link.
Download android.jar here (this is SDK for 2.2 + Android level API). This is compatible with around 90% targets devices now.