Java 6 is outdated and will not be updated anymore. Using it is a security risk.
Java 7 offers some great new features.
New and Noteworthy Features in Java 7
In this section MatthesRieke and DanielNuest quickly mention some features that shold become part of our daily software development because the considerably improve the code. More information can be found in the links at the bottom.
Use it instead of java.io - much easier to use and very useful (convenience) functionality for file and folder watching, file copying.
Base class to start with: Paths.java and it's static methods.
Makes instantiations short and readable (can even be warned about by the compiler): Write
Map<String, List<Trade>> trades = new TreeMap <> ();
Map<String, List<Trade>> trades = new TreeMap <String, List<Trade>> ();.