My take: you do not truly understand modularity until you have had to work with a third party framework where your software is integrated as plugin. Working wit

My take: you do not truly understand modularity until you have had to work with a third party framework where your software is integrated as plugin. Working with Eclipse / PDE / CDT has taught me more about modularity (good and bad) in 2 years than a decade of green field development (plus, I can now write a usable Eclipse plugin faster that I can write the equivalent Vim function ...). I also recommend "Practical API Design" (which contains both large scale advise and tiny but important details regarding source compatibility vs binary compatibility with aspects that have been unknown to me after several years of developing Java) and "Java Application Architecture" (which contains decoupling strategies, but you only learn to appreciate those after you have encountered the generic problem pattern).