Implementing a barcode scan Without installing a barcode application

Question

Possible duplicate:
Integrating the ZXing library directly into my Android application

I want to scan a barcode from my Android application without installing a third-party barcode scanner application. I downloaded the ZXing source code. When I click a button in my application, the barcode scan window should start. What are the methods that I need to call from my application to successfully scan barcodes.

Can anyone help me in solving this problem?

Thanks at Advance.