Hi Abimaran,
Android includes a dx tool for converting Java classfiles to the DEX format, which the Dalvik virtual machine understands. Before you could use this technology in the case of register based micro-controllers with Java, I believe that you would need to learn more about Dalvik and DEX. Here are a few resources to help you get started:
Dalvik (software)Dex File FormatHow the Dalvik Virtual Machine Works on Google Android
You might also find the following
glossary definitions from Google's Android Developer's Guide to be helpful:
.apk file
Android application package file. Each Android application is compiled and packaged in a single file that includes all of the application's code (.dex files), resources, assets, and manifest file. The application package file can have any name but must use the .apk extension. For example: myExampleAppname.apk. For convenience, an application package file is often referred to as an ".apk".
.dex file
Compiled Android application code file.
Android programs are compiled into .dex (Dalvik Executable) files, which are in turn zipped into a single .apk file on the device. .dex files can be created by automatically translating compiled applications written in the Java programming language.
I hope this helps you.
Jeff