Doing C# long enough, you get yourself familiar with C# concepts and syntax. That's fine, but sometime when you need "the same" concepts in Java, it's quite difficult. This cheat sheet here to tackle that problem.
Java for Beginner – 1 – Introduction to Java from a .NET guy
Coming to Java world, from a .NET guy, is like going from a full feature-rich and comfortable car to a basic bike with a lot of space for extension and customization.
Tuan Tran's Blog 