There are lots. Try the Java™ Tutorials (part of that chapter), and books like Java 8/9 in Action (or Modern Java in Action: different name for the same book) by Urma Fusco and Mycroft, or Naftalin's Mastering Lambdas. Naftalin also has an FAQ. I hope you will find those helpful; there are many other sources.
Moving discussion to our Java8 forum.
posted 2 years ago
A few minutes ago, I wrote:Moving discussion to our Java8 forum.
Also look through the Java8 forum because there are several good explanations in that forum.