Excellent advice. Reading other people's (good) code is one of the best ways to learn how real world problem solvers solve real world problems.
The Java standard library is interesting and easy to jump into if you work with it every day. Guava is another good library to study.
I personally spend a lot of time looking at Riak, Cassandra, Hadoop, and Postgres since developing databases is my day job. I also follow mailing lists for both developers and users to understand the real world outcomes of their design choices and use that to inform how I think rather then going into every problem a blank slate.
The Java standard library is interesting and easy to jump into if you work with it every day. Guava is another good library to study.
I personally spend a lot of time looking at Riak, Cassandra, Hadoop, and Postgres since developing databases is my day job. I also follow mailing lists for both developers and users to understand the real world outcomes of their design choices and use that to inform how I think rather then going into every problem a blank slate.