Java 8 in Action: Lambdas, streams, and functional-style programming

Chapter 4. Introducing streams

This chapter covers

• What is a stream?
• Collections vs. streams
• Internal vs. external iteration
• Intermediate vs. terminal operations

Collections is the most heavily used API in Java. What would you do without collections? Nearly every Java application makes and processes collections. Collections are fundamental to many programming tasks: they let you group and process data. To illustrate collections in action, imagine you want to create a collection of dishes to represent a menu and then iterate through it to sum the calories of each dish. You may want to process the collection to select only low-calorie dishes for a special healthy menu. But despite collections being necessary for almost any Java application, ...