Java is an object-oriented programming language for applications and websites that was first released by Oracle in 1995. While Java has lost some of its popularity as a client-side programming language, it still sees heavy use in server-side applications — especially at big sites like Amazon and eBay. If you want to implement server-side features powered by Java, you'll want to make sure that your website host supports the use of Java.
Moving to another website consists of transferring the website’s files and databases, configuring your site with the new host, and directing your domain’s DNS to the new host. Once you pick a new site host, they can usually help you out with this process. The cost will depend on the host you’re switching to, but it will probably be anywhere from $150-$400.