The Problem Lambdas Solve Every Java 7 developer has written the same five lines of boilerplate to sort a list or run a background task. Lambda expressions eliminate that ceremony entirely — and once you understand target typing, closures, and composition, you will find yourself reaching for them in every layer of a codebase: validation pipelines, event systems, retry logic, and beyond. Before Java 8, passing behaviour as a value required an anonymous inner class: