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.
Hadoop skills are in demand, but just getting a certificate is unlikely to be enough. Working with Hadoop requires a mix of programming skills (typically in Java although you can use other languages in various ways) and data skills. It's a pretty complicated beast of a tool, and MapReduce is a distinctive paradigm in itself which doesn't necessarily suit all application areas, so without some real-world experience of developing data-oriented applications, you'd probably struggle to find an employer willing to take you on, unless they're looking for a graduate trainee anyway.