Hello guys, once you learn Java and done with reading some of the best known introductory books on Java and have a couple of years of experience under your belt, you would be hungry to transition from an intermediate Java developer to an expert Java programmer, also known as Java guru. This transition is not smooth, and I have seen many Java developers having 2 to 6 years of experience stuck where they are and have absolutely no knowledge of advanced topics like JVM internals, Concurrency, Garbage collection, and Performance tuning.