This week's book giveaway is in the OCAJP forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide 1Z0-808 and have Jeanne Boyarsky & Scott Selikoff on-line! See this thread for details.
Imran First you need to specify which pattern you're interested in - I'm sure people here know of specific sites or references for specific patterns. The other thing you can try is to go to Google or another search engine and do a search for that pattern and include 'Java' as one of the search words.