Apouc 2014-java-8-create-the-future

Java 8:
Create The Future
Simon Ritter
Head of Java Technology Evangelism
Oracle Corp.

Program Agenda
 Java SE 8: Enhancing the Core Java Platform
– Lambdas and Streams
– Other new features
 Java ME 8: Building The Internet of Things
 NetBeans 8: The IDE For Java 8
 Where Next?

Java SE 8:
Lambdas & Streams:
Functional Programming
In Java

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014
1.4 5.0 6 7 8
java.lang.Thread
java.util.concurrent
(jsr166)
Fork/Join Framework
(jsr166y)
Project Lambda
Concurrency in Java
Phasers, etc
(jsr166)

The Problem: External Iteration
List<Student> students = ...
double highestScore = 0.0;
for (Student s : students) {
if (s.gradYear == 2011) {
if (s.score > highestScore) {
highestScore = s.score;
}
}
}
• Client controls iteration
• Inherently serial: iterate from
beginning to end
• Not thread-safe because
business logic is stateful
(mutable accumulator
variable)

Internal Iteration With Inner Classes
 Iteration handled by the library
 Not inherently serial – traversal may
be done in parallel
 Traversal may be done lazily – so
one pass, rather than three
 Thread safe – client logic is stateless
 High barrier to use
– Syntactically ugly
List<Student> students = ...
double highestScore = students.
filter(new Predicate<Student>() {
public boolean op(Student s) {
return s.getGradYear() == 2011;
}
}).
map(new Mapper<Student,Double>() {
public Double extract(Student s) {
return s.getScore();
}
}).
max();

Internal Iteration With Lambdas
SomeList<Student> students = ...
filter(Student s -> s.getGradYear() == 2011).
map(Student s -> s.getScore()).
max();
• More readable
• More abstract
• Less error-prone

Lambda Expressions
 Lambda expressions represent anonymous functions
– Same structure as a method
 typed argument list, return type, set of thrown exceptions, and a body
– Not associated with a class
 We now have parameterised behaviour, not just values
Some Details
filter(Student s -> s.getGradYear() == 2011)
map(Student s -> s.getScore())
max();
What
How

Lambda Expressions
 Definition
– A functional interface is an interface with only one abstract method
– However, the interface may have more than one method
 Identified structurally
– Type is inferred from the context
– Works for both assignment and method parameter contexts
 The type of a Lambda expression is a functional interface
– Instances of functional interfaces are created with Lambda expressions
– @FunctionalInterface annotation
Functional Interfaces

Type Inference
 The compiler can often infer parameter types in a lambda expression
 Inferrence based on the target functional interface’s method signature
 Fully statically typed (no dynamic typing sneaking in)
– More typing with less typing
List<String> list = getList();
Collections.sort(list, (String x, String y) -> x.length() - y.length());
Collections.sort(list, (x, y) -> x.length() - y.length());
static T void sort(List<T> l, Comparator<? super T> c);

Lambda Epressions
• Lambda expressions can refer to effectively final local variables from
the enclosing scope
– This means a variable behaves as if it is marked final (even if it is not)
– The variable is assigned once
• Lambda expressions are anonymous functions
– They are not associated with an object
– this will refer to the object in the surrounding scope
Local Variable Capture & The Meaning of ‘this’

Method References
• Method references let us reuse a method as a lambda expression
FileFilter x = (File f) -> f.canRead();
FileFilter x = File::canRead;

Constructor References
 Same concept as a method reference
– For the constructor
Factory<List<String>> f = ArrayList<String>::new;
Factory<List<String>> f = () -> return new ArrayList<String>();
Equivalent to

Default Methods
 Provide a mechanism to add new methods to existing interfaces
– Without breaking backwards compatability
– Gives Java multiple inheritance of behaviour, as well as types
 but not state!
public interface Set<T> extends Collection<T> {
... // The existing Set methods
default Spliterator<E> spliterator() {
return Spliterators.spliterator(this, Spliterator.DISTINCT);
}
}

Static Methods In Interfaces
 Previously it was not possible to include static methods in an interface
 Static methods, by definition, are not abstract
– @FunctionalInterface can have zero or more static methods
static <T> Predicate<T> isEqual(Object target) {
return (null == target)
? Objects::isNull
: object -> target.equals(object);
}

Streams API
 Most business logic is about aggregate operations
– “Most profitable product by region”
– “Group transactions by currency”
 As we have seen, up to now, Java mostly uses external iteration
– Inherently serial
– Frustratingly imperative
 Java SE 8’s answer: Streams
– With help from Lambdas
Aggregate Operations

Stream Overview
 Abstraction for specifying aggregate computations
– Not a data structure
– Can be infinite
 Simplifies the description of aggregate computations
– Exposes opportunities for optimisation
– Fusing, laziness and parrallelism
High Level

Stream Overview
 A stream pipeline consists of three types of things
– A source
– Zero or more intermediate operations
– A terminal operation
 Producing a result or a side-effect
Pipeline
int sum = transactions.stream().
filter(t -> t.getBuyer().getCity().equals(“London”)).
mapToInt(Transaction::getPrice).
sum();
Source
Intermediate operation
Terminal operation

Stream Overview
 The filter and map methods don’t really do any work
– They set up a pipeline of operations and return a new Stream
 All work happens when we get to the sum() operation
– filter()/map()/sum() fused into one pass on the data
 For both sequential and parallel pipelines
Execution
int sum = transactions.stream().
filter(t -> t.getBuyer().getCity().equals(“London”)). // Lazy
mapToInt(Transaction::getPrice). // Lazy
sum(); // Execute the pipeline

Stream Sources
 From collections and arrays
– Collection.stream()
– Collection.parallelStream()
– Arrays.stream(T array) or Stream.of()
 Static factories
– IntStream.range()
– Files.walk()
 Roll your own
– java.util.Spliterator()
Many Ways To Create

Stream Sources
 Access to stream elements
 Decomposition (for parallel operations)
– Fork-join framework
 Stream characteristics
– ORDERED
– DISTINCT
– SORTED
– SIZED
– NONNULL
– IMMUTABLE
– CONCURRENT
Manage Three Aspects

Stream Intermediate Operations
 Uses lazy evaluation where possible
 Can affect stream characteristics
– map() preserves SIZED but not DISTINCT or SORTED
 Some operations fuse/convert to parallel better than others
– Stateless operations (map, filter) fuse/convert perfectly
– Stateful operations (sorted, distint, limit) fuse/convert to varying
degrees

Stream Terminal Operations
 Invoking a terminal operation executes the pipeline
– All operations can execute sequentially or in parallel
 Terminal operations can take advantage of pipeline characteristics
– toArray() can avoid copying for SIZED pipelines by allocating in
advance

Optional<T>
 Indicates that reference may, or may not have a value
– Makes developer responsible for checking
– A bit like a stream that can only have zero or one elements
Reducing NullPointerException Occurences
Optional<GPSData> maybeGPS = Optional.ofNullable(gpsData);
maybeGPS.ifPresent(GPSData::printPosition);
GPSData gps = maybeGPS.orElse(new GPSData());
maybeGPS.filter(g -> g.lastRead() < 2).ifPresent(GPSData.display());

java.util.function Package
 Predicate<T>
– Determine if the input of type T matches some criteria
 Consumer<T>
– Accept a single input argumentof type T, and return no result
 Function<T, R>
– Apply a function to the input type T, generating a result of type R
 Plus several more type specific versions

Stream Example 1
Convert words in list to upper case
List<String> output = wordList.
stream().
map(String::toUpperCase).
collect(Collectors.toList());

Stream Example 1
Convert words in list to upper case (in parallel)
parallelStream().
map(String::toUpperCase).

Stream Example 2
Find words in list with even length
stream().
filter(w -> (w.length() & 1 == 0).

Stream Example 3
 BufferedReader has new method
– Stream<String> lines()
Count lines in a file
long count = bufferedReader.
lines().
count();

Stream Example 4
Find the length of the longest line in a file
int longest = reader.
lines().
mapToInt(String::length).
max().
getAsInt();

Stream Example 5
Collect all words in a file into a list
List<String> output = reader.
lines().
flatMap(line -> Stream.of(line.split(REGEXP))).
filter(word -> word.length() > 0).

Stream Example 6
List of unique words in lowercase, sorted by length
List<String> output = reader.
lines().
flatMap(line -> Stream.of(line.split(REGEXP))).
filter(word -> word.length() > 0).
map(String::toLowerCase).
distinct().
sorted((x, y) -> x.length() - y.length()).

Java SE 8:
Other New Features

Annotations On Java Types
 Annotations can currently only be used on type declarations
– Classes, methods, variable definitions
 Extension for places where types are used
– e.g. parameters
 Permits error detection by pluggable type checkers
– e.g. null pointer errors, race conditions, etc
public void process(@notnull List data) {…}

Concurrency Updates
 Scalable update variables
– DoubleAccumulator, DoubleAdder, etc
– Multiple variables avoid update contention
– Good for frequent updates, infrequent reads
 ForkJoinPool improvements
– Completion based design for IO bound applications
– Thread that is blocked hands work to thread that is running

Parallel Array Sorting
 Additional utility methods in java.util.Arrays
– parallelSort (multiple signatures for different primitives)
 Anticipated minimum improvement of 30% over sequential sort
– For dual core system with appropriate sized data set
 Built on top of the fork-join framework
– Uses Doug Lea’s ParallelArray implementation
– Requires working space the same size as the array being sorted

Date And Time APIs
 A new date, time, and calendar API for the Java SE platform
 Supports standard time concepts
– Partial, duration, period, intervals
– date, time, instant, and time-zone
 Provides a limited set of calendar systems and be extensible to others
 Uses relevant standards, including ISO-8601, CLDR, and BCP47
 Based on an explicit time-scale with a connection to UTC

Base64 Encoding and Decoding
 Currently developers are forced to use non-public APIs
– sun.misc.BASE64Encoder
– sun.misc.BASE64Decoder
 Java SE 8 now has a standard way
– java.util.Base64.Encoder
– java.util.Base64.Decoder
– encode, encodeToString, decode, wrap methods

Nashorn JavaScript Engine
 Lightweight, high-performance JavaScript engine
– Integrated into JRE
 Use existing javax.script API
 ECMAScript-262 Edition 5.1 language specification compliance
 New command-line tool, jjs to run JavaScript
 Internationalised error messages and documentation

Removal Of The Permanent Generation
 No more need to tune the size of it
 Current objects moved to Java heap or native memory
– Interned strings
– Class metadata
– Class static variables
 Part of the HotSpot, JRockit convergence
Permanently

JavaFX 8
 DatePicker
 TreeTableView
New Controls

JavaFX 8
 Gestures
– Swipe
– Scroll
– Rotate
– Zoom
 Touch events and touch points
Touch Support

JavaFX 8
 Predefined shapes
– Box
– Cylinder
– Sphere
 User-defined shapes
– TriangleMesh, MeshView
 PhongMaterial
 Lighting
 Cameras
3D Support

Compact Profiles
Approximate static footprint goals
Compact1 Profile
Compact2 Profile
Compact3 Profile
Full JRE 54Mb
30Mb
16Mb
11Mb

Java SE Embedded
 Optimised binary for embedded use from devices to gateways
 Latest Java innovations in the smallest footprint
 Use of compact profiles
– Approximate JRE size 20.4Mb (ARM v7 VFS, Hard Float)
 Compact profile 1: 10.4Mb
 JavaFX: 10Mb
 Production ready binary for popular platforms that run Linux
– ARM v6/7 with Hard floating point
– Raspberry Pi is one of the reference platforms

Java ME 8:
Building The Internet of
Things

Java ME 8 Focus
Java ME EmbeddedJava Card
SECURITY SMALL EMBEDDED MEDIUM EMBEDDED LARGE EMBEDDED DESKTOP SERVER
50KB-1MB
1MB-10MB
10MB-100MB
Footprint
Java SE Embedded
Java Embedded Suite
Oracle Event Processing Embedded
100MB+
Java SE
ARM Cortex M3/M4
ARM Cortex-A

Java ME 8 Platform Overview
Java VM
Additional
APIs
(Examples)
Java ME Connected Limited Device Configuration (CLDC) 8 (JSR 360)
Additional
Optional APIs
On-Device I/O
Access
Vertical Specific
APIs
Location
Messaging
Wireless
Communication
Web Services
Protocols and
Data Conversion
Sensors
Additional
Optional JSRs
Security and
Management
Use Case Software
(e.g. smart pen)
Use Case Software
(e.g. wireless module)
Use Case Software
(e.g. control unit)
Use Case Software
(e.g. smart meter)
Application Platform
Java ME Embedded Profile
(MEEP) 8 (JSR 361)
On-Device I/O
Access
Device I/O
API
SATSA
(JSR 177)
Security and Trust
Services
Generic Connection
Framework
GCF 8

Java ME 8 Key Features
 Aligned with Java SE 8
– Language, libraries, VM
 Designed for embedded
– Fully headless operation
– Remote software provisioning and management
 Highly portable and scalable
– Minimum RAM footprint of 1Mb
 Consistent across devices

Java ME 8 Key Features
 Advanced application platform
– Multi-application model
 Modularised software services
– Faster and more flexible software development and deployment
 Multi-client domains (“partitioning”)
– Different clients can have different security domains
 Access to peripheral devices (Device I/O API)
 Compatible with JCP/JSR standard APIs

Generic Connection Framework 8
 SecureServerConnection
 SecureDatagramConnection
 ModemConnection
 UDPMulticastConnection
 CommConnection
 HttpConnection
 HttpsConnection
 SecureConnection
 ServerSocketConnection
 SocketConnection
 UDPDatagramConnection
Substantially Increased Range of Connection Types

MEEP 8
Java ME Embedded Profile (MEEP) 8
Architecture
CLDC 8
javax.
microedition.
midlet
NEW
UPDATED
javax.
microedition.
io
(optional)
javax.
microedition.
event
(optional)
javax.
microedition.
key
(optional)
javax.
microedition.
lui
(optional)
javax.
microedition.
media
(optional)
javax.
microedition.
power
(optional)
javax.
microedition.
rms
(optional)
javax.
microedition.
swm
(optional)
javax.
microedition.
cellular
(optional)
Application or Service

NetBeans 8:
The IDE For Java 8

Tools for Java SE 8
 Quickly convert
anonymous
inner
classes
to lambdas
Lambda Expressions

Tools for Java SE 8
 Static analysis
to ensure
safe transformation,
automatically
add cast
for correct type
Lambda Expressions

Tools for Java SE 8
 Smoothly convert
to internal iterators
via hints and tips
Internal Iterators via Java 8 Streams

Tools for Java SE 8
 Easily convert
from lambdas
to method references
Method References

Tools for Java SE 8
 Specify a scope
for upgrading to Java 8
– All/current projects
– Specific package
– Specific class
 Run converters
 Visually preview
proposals for
refactoring
Refactoring in Batch Mode

Tools for Java SE Embedded 8
 Full Development Cycle support
against a remote platform
– Intuitive development
– One-click deploy
– Remote debugging
– Comprehensive remote profiling
 Complete end to end integration
for Raspberry Pi and other
embedded devices,
– e.g.Web Services.
Seamless Integration

Tools for Java ME Embedded 8
 Java ME 8 CLDC
Platform Emulator
 Intuitive tools and editors
for JDK 8 on Java ME
 Simple customization
of optional packages
Seamless Integration

Where Next?

To Java SE 9 and Beyond!
Jigsaw
Cloud
Ease of use
Optimizations Generic Lang Interoperability
Penrose
OpenJFX
Project Sumatra – Java for GPUs
Ports: Power PC/AIX
Multi-Tenancy Support
Self Tuning JVM
Improved Integration with Native
Resource Management
Lang Enhancements
Unified Type System
Data Structure Optimizations

Conclusions
 Java SE 8 adds powerful new features to the core
– Lambda expressions, streams and functions
– New controls, stylesheet and 3D support in JavaFX
 Java ME 8 focused on embedded development
– Device I/O APIs
 NetBeans 8, ready for Java 8 development
– Lambda support, embedded support
 Java continues to evolve

Apouc 2014-java-8-create-the-future

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