book

Java Closures and Lambda

by Robert Fischer

March 2015

Intermediate to advanced

220 pages

6h 11m

English

Apress

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Java 8 Returns Java to the ForefrontJava Has Had Functional Programming All AlongJava 8 Is Not Just Syntactic SugarIs Java 8 a Functional Programming Language?Enough with the Theory; onto the Implementation!

Java 8’s Lambda SyntaxLambdas as ClosuresNo-Argument and Multi-Argument LambdasLambdas with No Return ValueLambdas with Complex BodiesLambdas with Explicit TypingLambdas as OperatorsLambdas as PredicatesLambdas with Primitive ArgumentsMaking Methods into LambdasMaking Static Methods into LambdasMaking Constructors into LambdasMaking Instance Methods into LambdasSpecifying a Method to Be Used LaterLambdas as Interface ImplementationsDefault MethodsStatic MethodsFunctional Interface Helper MethodsFunction.identity() and UnaryOperator.identity()Function.compose and Function.andThenConsumer.andThenPredicate.and and Predicate.orPredicate.isEqualPredicate.negateBinaryOperator.minBy and BinaryOperator.maxByLambda Best PracticesUse InterfacesUse Method ReferencesDefine Lambdas InlineLambdas Should Always Be ThreadsafeDon’t Use NullDon’t Release ZalgoBuild Complexity from Simple PartsUse Types and the Compiler to Your Advantage
Lambdas and Functional ProgrammingFunctional IterationManipulating Collections and Maps with LambdasFiltering Collections and MapsMapping Collections and MapsMap ComputationsStreamsStream CreationMapping and Filtering StreamsCollecting, Processing, or Reducing StreamsPrimitive StreamsLambda’s Domain in Review
Temporary Files and the Hole in the MiddleException Handling via Input: Passing in an Exception HandlerException Handling via Output: Capturing Execution ResultsConsuming Our Temp File FunctionReading All the Lines of Files in a DirectoryComplex Stream Processing Using Creative FlatteningStreaming all the Lines of all the Files in a DirectorySummary
Representing the Intermediary Query ResultsPrinting Out the ResultsMapping the ResultSet to a StreamMethod One: Building a Stream Using the Stream BuilderMethod Two: Building a Stream Using Stream.of and Stream.flatMapMethod Three: Building a Stream Using an AbstractSpliteratorMethod Four: Building a Stream from an IteratorPulling It All Together
Lambdas and Classic Java ThreadingLambdas and ExecutorsLambdas and the ThreadPoolExecutorLambdas and Fork/JoinStream ParallelismConclusion
Resources and ExceptionsHandling Resources by Throwing an Unchecked ExceptionHandling Resources with an Exception-Handling CallerHandling Resources Using a Result ObjectBridging Collections and StreamsBridging Arrays and StreamsMaking Interfaces More Lambda FriendlyImplementing Abstract Classes via LambdasThe Transparent Optional TrickDeveloping Backwards
Hello, BytecodeMethod References in BytecodeBound Instance Method References in BytecodeFree Instance Method References in BytecodeInline Lambda Definitions and Lambda LiftingConclusion
Imperative Programming ParadigmObject-Oriented Programming ParadigmPost-Functional Programming ParadigmOther Programming ParadigmsLogical/MathematicalHomoiconicDeclarativeReactiveStack-Based (Concatenative)Post-ModernParadigms, Style, and Post-Functional Programming

Overview

Java Closures and Lambda introduces you to significant new changes to the Java language coming out of what is termed Project Lambda. These new changes make their debut in Java 8, and their highlight is the long-awaited support for lambda expressions in the Java language. You’ll learn to write lambda expressions and use them to create functional interfaces and default methods for evolving APIs, among many other uses.

The changes in Java 8 are significant. Syntax and usage of the language are changed considerably with the introduction of closures and lambda expressions. This book takes you through these important changes from introduction to mastery. Through a set of clear examples, you’ll learn to refactor existing code to take advantage of the new language features. You’ll learn what those features can do for you, and when they are best applied. You’ll learn to design and write new code having these important new features in mind from the very beginning.

Clearly explains the fantastic benefits resulting from Project Lambda

Explains the syntax and IDE support for the new features

Shows how to streamline your code by bringing some of the benefits of functional programming to the Java language

Illustrates parallelism in closures through Stream and Spliterator objects

Explains API evolution by adding methods to existing interfaces without breaking existing interface implementations, a technique addressing potential multiple inheritance issues