I am working on a project and i have tested it on nexus one. its working there properly but I want that my project should be compatible with all screen sizes. How to do this
This guy has some great blogs about how to handle multiple screen sizes in your android applications. They're titled Handling Multiple Screen Sizes and there are 5 parts:
http://www.androidguys.com/2010/02/16/handling-multiple-screen-sizes-part/
http://www.androidguys.com/2010/02/18/handling-multiple-screen-sizes-part-2/
http://www.androidguys.com/2010/02/23/handling-multiple-screen-sizes-part-3/
http://www.androidguys.com/2010/03/01/handling-multiple-screen-sizes-part-4/
http://www.androidguys.com/2010/03/02/handling-multiple-screen-sizes-part-5/
Read through them and you should have a better understanding of all the things you need to do.