Java
Besides lambdas expressions, Java 8 introduced another language syntax change in the form of a new operator, :: (double colon), to create so-called method references.
Even though interfaces and abstract classes have many similarities at first look, especially after introducing default methods, they have different use cases and capabilities.
The concept of traversing elements with Iterators is supported since Java 1.2, but got a new relative in Java 8: java.util.Spliterator
Iterating data structures is one of the most common tasks. Everyone knows the classics, like for or while. But there are more ways to iterate in Java, providing a lot more functionality.
Dealing with date and time is a cumbersome task in many programming languages. But with Java 8, the JDK provides us with a comprehensive and completely new API, changing the way we deal with time-related concepts.
The concept of map/filter/reduce is a cornerstone of any functional programming. Data pipelines consist of one or more intermediate operations that represent one of these three methods.