'Adaptive Code' by Gary McLean Hall is an informative read on modern software design, its both concise and well-written https://www.amazon.com/Adaptive-Code-via-principles-Develope...

note, that a second edition is scheduled for release Jan/2017 https://www.amazon.com/Adaptive-Code-principles-Developer-Pr...

I would also recommend 'Effective Java' by Josh Bloch https://www.amazon.com/Effective-Java-2nd-Joshua-Bloch/dp/03...

you'll find the advice given in both immediately applicable