How to build an APK file in Eclipse?

For testing on a device, you can connect the device using USB and run from Eclipse just as an emulator.

If you need to distribute the app, then use the export feature:

Then follow instructions. You will have to create a key in the process.

When you run the project on the emulator, the APK file is generated in the bin directory. Keep in mind that just building the project (and not running it) will not output the APK file into the bin directory.