One Source, Some Steps, One Result

Six things this topic established, and where each one was.

What the topic established, and which card it was on
The thing	Where
Intermediate operations describe; terminal operations run	A Pipeline That Does Nothing at All
The terminal operation pulls one element at a time through the whole chain	Watching a Pipeline Touch Three Elements
`map` gives one value per element; `flatMap` flattens several into one stream	map Against flatMap
`collect` and `groupingBy` decide the shape at the end	Collecting Into a List, a Set and a Map
A stream holds a way of pulling elements, so it cannot be run twice	Why You Cannot Use a Stream Twice
Parallel costs splitting and combining before it saves anything	Why parallel() Made It Slower

A pipeline is a description of work, pulled by its last line. Every surprise in this topic — nothing happening, a stream that will not run twice, three hundred elements touched out of a thousand — is that one fact showing through.

Java
Java Streams