Functional Java: Master Java Lambdas and Streams

Transform methods into lambda expressions in Java using arrow syntax, type inference, and one-line versus multi-line bodies to pass behavior as values.

Explore lambda expression examples, learn how to assign lambdas to variables, infer input types, handle single and multiple arguments, and distinguish returning values from void bodies.

Prioritize readability over expression size when choosing lambda expressions in Java, using inferred types. Functional programming is a tool within object oriented Java, not a replacement.

Learn how Java lambda expressions are implemented via functional interfaces, using the single abstract method rule to ensure type safety and backward-compatible, interface-based function types.

Explore how to type a lambda in Java by defining interface methods that specify argument count, order, and return type; use a single-method interface as a proxy to type lambdas.

Understand how a single abstract method in an interface defines the lambda signature, letting you assign a lambda to that interface type by matching its method inputs and return.

Explore lambda expressions in Java by building a functional interface, assigning lambdas to variables, and executing them through the interface method, illustrating first-class functions and JVM behavior.

Learn how interface typing, based on the interface's single abstract method, guides lambda expressions in Java; two interfaces with the same method signature aren’t inter assignable.

Apply lambda expressions to a functional interface with a single abstract method, pass inline lambdas to a task runner, and demonstrate backward compatibility with legacy code.

Use the functional interface annotation to enforce a single abstract method, catching errors when a second abstract method is added; lambdas work without it, but it communicates intent.

Demonstrate using lambdas with a functional interface to perform integer operations like addition and subtraction. The do math operation method applies the chosen operation to two numbers and returns result.

Explore how lambdas differ from anonymous classes by passing behavior instead of a concrete object, with invokedynamic enabling lazy execution and avoiding object creation.

Java's functional interface typing prevents inter assignment even when signatures match, creating interface overhead; use built-in JDK functional interfaces to reduce boilerplate and improve interoperability.

Explore JDK functional interfaces in java.util.function, covering common lambda signatures across four categories—functions, consumers, suppliers, and predicates—with examples of how to choose the right interface.

Explore the function interface in Java, using generics to map one input to one output. See how lambda expressions fit the functional interface and autoboxing for primitives.

Defines and demonstrates consumer, supplier, and predicate as Java functional interfaces, with a greeting lambda printing a name and a runnable for no-argument, no-return code used in streams.

Explore JDK functional interfaces with hands-on examples of function, consumer, supplier, and predicate. Learn how to write lambdas, call their abstract methods (apply, accept, get, test), and use method references.

Define arity as the number of input arguments, classify nullary, unary, binary, and ternary functions, and show unary and binary coverage for by function, by consumer, and by predicate.

Understand unary operator and binary operator as specialized functional interfaces that extend function. These shortcuts preserve type and enable interoperability, but come with trade-offs in readability and API flexibility.

Explore method references in Java to replace simple lambdas, delegating work to static methods like Math.random, and use ClassName::methodName to keep IntelliJ happy.

Explore method reference usage in Java, including static and instance forms, how lambda inference works, and practical examples like println, string trim, ignore-case equals, and predicate compare.

Learn how to replace lambdas with method references in Java's functional programming style, using instance and constructor references to simplify code, with examples like getName, equals, and list deduping.

Master passing lambdas to other lambdas, implement higher order functions, and compose small functional pieces through currying and function composition in Java.

Explore how to compose java lambdas with andThen and compose to orchestrate runtime behavior, enabling flexible function chaining and reusable parts like log messages and string processing.

Examine how closures capture scope in Java lambdas, remembering the value instead of the variable. Learn why variables used in lambdas must be final or effectively final.

Explore pure functions in Java lambdas and streams, learning to avoid external state for deterministic outputs. Compare pure versus impure functions and embrace testable side effect free code.

Explore streams as a design pattern for processing elements in collections, offering an internal iteration model with lambdas and a reusable examine method.

Compare declarative and imperative code, and discover how Java streams offer a declarative way to process collections beyond loops. See SQL style examples that convey intent.

Explore the streams API as a declarative, lazy, and parallel way to process collections, using lambdas and functional programming operators for composable, efficient data processing.

Learn how streams form a single-use, lazy, declarative data pipeline, illustrated by an assembly line analogy. Apply operations like trim, uppercase, and filter along a chained pipeline; streams are immutable.

Create a stream from a collection and apply operations with a forEach consumer, using a lambda or method reference to print each element.

Explore multiple ways to create streams beyond collections, including stream off and arrays stream, file lines, and generate or iterate patterns, while recognizing streams as independent processing lines.

Explore converting a stream to a list with the toList method by generating a range of numbers via iterate and limit, then collecting the first 100 elements.

Identify the three key elements of streams: the stream itself, intermediate operations, and terminal operations. Compare sequential and parallel streams, and note how terminal operations yield results or side effects.

Compare streams and collections, highlighting streams' immutability and laziness, side effect free transformations, and built in parallel processing for safe, declarative data processing and improved composability.

Learn how immutable streams return new streams from each operation, and how limit and filter act as fluent API operators, using predicates to select values while emphasizing operation order.

Use the map operator to transform each stream element, like capitalizing names with toUpperCase, and place limits or filters up front to optimize performance while avoiding side effects.

Discover the peek operator in Java streams, enabling debugging by peeking into map and filter results with a consumer for side effects like printing, while returning a new stream.

Discover the difference between terminal and intermediate stream operations, such as foreach and peek, and how lazy evaluation determines when streams execute and produce a list.

Distinct and sorted operators in streams: distinct removes duplicates by remembering previous elements; sorted waits for the terminal operation to see items, risking memory issues with large or infinite streams.

Concatenate two streams with Stream.concat to produce a new stream that combines elements from both streams in order, demonstrated by iterating with foreach.

Learn how Java streams process objects by filtering a student stream with a predicate, mapping to names, and collecting results into a list of strings.