The Java™ Tutorials : Aggregate Operations

The Java Tutorials are practical guides for programmers who want to use the Java programming language to create applications. They include hundreds of complete, working examples, and dozens of lessons. Groups of related lessons are organized into "trails". (The full tutorials https://docs.oracle.com/javase/tutorial/)

Let us stress this week on

Aggregate Operations:

Prerequisite:  Lambda Expressions and Method References.

Then follow the Aggregate Operations tutorial