Covariance and contravariance might seem esoteric, but you'll need these concepts more than ever as the Java language evolves. Get started with type dependency in array types, generic types, and ...

You might know that Java passes by value, but it helps to understand why. Here's what happens when you pass mutable and immutable object references in Java.

This post explains how to use variables in Java. Learn the primitive types (and what that means) and just why variables are so important for any coding!