This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
Instead of writing a search engine from scratch in java, if it is possible you can use a third party search engine which is compatible with applications written in Java like Inktomi's Inktomi search software(formerly known as Ultraseek). This search engine comes with a Java API to enable integration with Java applications and extend search engine's capabilities. You can get more information from http://www.inktomi.com/products/search//products/ultraseek/index.html Hope this helps.