Java 8 brought many new patterns to build efficient and clean applications. In this course, we cover one most important new thing: lambda expressions. Lambdas are a nice thing, but would be useless without new patterns to process data. These new patterns have been added to the Collection Framework, and to a the new Stream API. This course quickly explains what the map / filter / reduce pattern is about, and why is has been added to the Stream API. This new API is precisely described: how it can be used to efficiently process data and how it can be used in parallel. Caveats and corner cases are also shown.