Java 8 Features Full Tutorial | Lambda Expressions, Stream API, Functional Interfaces & Optional

🎯 Hook Java 8 changed everything. Lambda expressions, the Stream API, and functional interfaces transformed how we write Java — less boilerplate, more expressive code. This video covers every major Java 8+ feature you'll need for modern development, from your first lambda to chaining complex stream pipelines. 📌 Topics Covered • Why Java 8? — the shift toward functional programming in Java • Lambda expressions — syntax, target typing, and effectively final • Functional interfaces — @FunctionalInterface and the single abstract method rule • Built-in functional interfaces • Method references — static (Class::method), instance (obj::method), constructor (Class::new) • Stream API — what a stream is (not a data structure; a pipeline of operations) • Intermediate operations: filter(), map(), flatMap(), sorted(), distinct(), limit(), peek() • Terminal operations: forEach(), collect(), count(), reduce(), findFirst(), anyMatch() • Collectors — toList(), toSet(), toMap(), groupingBy(), joining() • Parallel streams — when they help and when they hurt • Optional T — avoiding NullPointerException; isPresent(), ifPresent(), orElse(), map() • Default and static methods in interfaces — why they were added • New Date and Time API — LocalDate, LocalTime, LocalDateTime, Duration, Period, DateTimeFormatter 🗒️ What Makes This Video Different Every Stream operation is demonstrated with a real data set (list of employees, orders) so you can see functional pipelines in a practical context — not just with integers. ⏱️ Timestamps • 0:00 Introduction — Why Java 8 Matters • 0:50 Lambda Expressions — Syntax & Scope • 12:10 Functional Interfaces & @FunctionalInterface • 24:40 Predicate, Function, Consumer, Supplier • 35:30 Method References (All 4 Types) • 45:20 Stream API — What Is a Stream? • 55:00 Intermediate Operations (filter, map, flatMap) • 1:07:00 Terminal Operations (collect, reduce, count) • 1:16:00 Collectors — groupingBy, joining • 1:24:00 Optional T • 1:32:00 Default & Static Methods in Interfaces • 1:38:00 New Date and Time API • 1:46:00 Summary & When to Use Each Feature 👥 Who Is This Video For? • Java developers moving from Java 7 or older codebases to modern Java • Students preparing for modern Java interview questions • Backend developers who want to write cleaner, functional-style code • Anyone who wants to understand what lambdas and streams actually do 🏷️ Hashtags #Java #Java8 #LambdaExpressions #StreamAPI #FunctionalProgramming #Optional #MethodReferences #JavaInterview #LearnJava #ModernJava