Java World, Java Trends, Java 8 and Beyond (iForum - 2014)

Java
Java World, Java Trends, Java 8 and Beyond Olena Syrota
@osyrota

Agenda
▪ Java Today
▪ Java Trends
▪ Java 8
▪ Beyond Java 8
2

Java Birthday
▪ Started in 1991
▪ Released in 1995
Who of you was born in
1991?
4

Java Today - Advantages
▪ Stable
▪ High performance
▪ Backward compatibility
▪ JVM
▪ Mature culture of build tools and practice
▪ JCP process and community involvement
▪ etc
6

Java Today - Disadvantage
▪ A lot of boilerplate code (imperative programming style)
▪ Every language has lambda 
7

Trends
▪ Polyglot development
▪ Languages over JVM (Scala, Groovy, Clojure etc)
▪ Reduce boilerplate code
▪ Java 8 - Lambdas
▪ Maximum using of checking code conditions at compile time
▪ Lambda 8 - Typed annotations
▪ Internet of Things
▪ Java on Raspberry Pi
8

Java 8 Released 18 March 2014
▪ 55 new features
in Java SE 8
10

Java SE 8 “Umbrella” Specification
JSR 337
▪ https://www.jcp.org/en/jsr/detail?id=337
▪ Expert Group
▪ Kevin Bourrillion (Google)
▪ Andrew Haley (Red Hat)
▪ Steve Poole (IBM)
▪ Mark Reinhold (Oracle)
11

Java 8
Java for Everyone
• Profiles for constrained devices
• JSR 310 - Date & Time APIs
• Non-Gregorian calendars
• Unicode 6.2
• ResourceBundle.
• BCP47 locale matching
•Globalization &
Accessibility
Innovation
• Lambda aka Closures
• Language Interop
• Nashorn
Core Libraries
• Parallel operations for core
collections APIs
• Improvements in functionality
• Improved type inference
Security
• Limited doPrivilege
• NSA Suite B algorithm support
• SNI Server Side support
• DSA updated to FIPS186-3
• AEAD JSSE CipherSuites
Tools
• Compiler control & logging
• JSR 308 - Annotations on
Java Type
• Native app bundling
• App Store Bundling tools
Client
•Deployment enhancements
•JavaFX 8
•Java SE Embedded support
•Enhanced HTML5 support
•3D shapes and attributes
•Printing
General Goodness
• JVM enhancements
• No PermGen limitations
• Performance lmprovements
12

Java 8 Features to Discuss
▪ Lambda
▪ Bulk operations for collections
▪ Parallel operations on collections
▪ Date and Time API
▪ Annotations on Types
▪ Nashorn
14

Lambdas
▪ The most significant changes and innovation in Java
▪ Lambda (closures)
▪ Interface evolution (functional interfaces and default methods)
▪ Evolution of Collections library (bulk operations)
▪ Simplified syntax of parallel computation with libraries
15

Lambda Sample
interface Adder {
int add (int a, int b);
}
Adder adder = (a, b)->a+b;
17

Impact of Lambda
▪ Passing behavior as parameter has great impact on code
▪ Control is transferred from client to library
18

Internal Iteration
public void internalIteration(List<Person> voters) {
voters.forEach(v->System.out.println(v));
}
19

Parallel Internal Iteration
public void internalIteration(List<Person> voters) {
voters.parallelStream().forEach(v->System.out.println(v));
}
20

Bulk Operations on Collections
public static List<Person> eligibleVoters(List<Person> potentialVoters,
int legalAgeOfVoting) {
return potentialVoters
.stream()
.filter(s->s.getAge()>=legalAgeOfVoting)
.collect(Collectors.toList());
}
21

More Bulk Operations
public static double averageAgeOfVoters(List<Person> voters) {
return voters
.stream()
.mapToInt(v->v.getAge())
.average()
.getAsDouble();
}
22

Sequential version
public static Set<Ballot> unspoiledBallots(Set<Ballot> ballots) {
return ballots
.stream()
.filter(b->!b.isSpoiled())
.collect(Collectors.toSet());
}
23

Parallel version
public static Set<Ballot> unspoiledBallots(Set<Ballot> ballots) {
return ballots
.parallelStream()
.filter(b->!b.isSpoiled())
.collect(Collectors.toSet());
}
24

Parallel Computations in Java:
form Thread to Project Lambda
25

Interface Evolution
▪ Functional interfaces
▪ Default methods
26

Interface Evolution
▪ Standard interface Collection has new method forEach
Default method – new feature
of language.
Virtual method can have default
implementation.
This allows to transfer control
over iteration to library.
interface Collection<T> extends Iterable<T> {
default void forEach (Block<T> action) {
for (T t: this) {
action.apply(t);
}
}
}
27

Interface Evolution
Functional interface – allows to
pass behavior as parameter
interface Collection<T> extends Iterable<T> {
default void forEach (Block<T> action) {
for (T t: this) {
action.apply(t);
}
}
}
@FunctionalInterface
interface Block<T> {
void apply(T t);
}
28

Java 8 Added Plenty of New
Features
▪ Java 8 is biggest update to java
programming model
▪ Small set of features, with a big impact
▪ Lambda expressions
▪ Default methods
▪ Bulk operations on collections
▪ Coordinated co-evolution of
▪ language
▪ libraries
▪ APIs
29

Date and Time API
▪ Why new Date and Time API?
▪ Immutable-value classes ( immutable => thread-safe)
▪ Domain-driven API design
30

Date and Time API Sample
public static Period periodBetweenIFormAndLongestDay() {
LocalDate iForumDay = LocalDate.of(2014, 04, 24);
LocalDate longestDay = iForumDay.with(Month.JUNE).withDayOfMonth(22);
return Period.between(longestDay, iForumDay);
}
31

Annotations on Java Types
▪ Before the Java SE 8 release, annotations could only be
applied to declarations (class, constructor, method, field,
local variable, parameter etc.)
▪ As of the Java SE 8 release, annotations can also be
applied to any type use (e.g. generic type arguments, new,
casts, implements, throws)
32
Map<@NonNull String, @NonEmpty List<Document>> files;
myString = (@NonNull String) myObject;

Error Detection at Compile-Time
▪ A compiler plug-in enables a programmer to find bugs or to
verify their absence
▪ E.g. null pointer, immutability etc
33

Checker Framework
34
import org.checkerframework.checker.nullness.qual.NonNull
public class CheckerProof {
public static void main(String[] args) {
String str=null;
proof(str);
}
public static void proof(@NonNull String s) {
System.out.println(s);
}
}
Checker.java:5: error: [argument.type.incompatible] incompatible types in argument.
proof(str);
^
found : @FBCBottom @Nullable String
required: @Initialized @NonNull String
1 error

Nashorn – JavaScript Engine for JVM
▪ You can implement you code in JavaScript
▪ Java seen from Nashorn
▪ Nashorn seen from Java
▪ Applications
▪ Client (Extending FX)
▪ Embedded/Mobile
▪ Server-side scripting
▪ Server-side JavaScript on the JVM with Nashorn (Avatar.js)
35

jjs - command-line tool (JDK)
jjs Hello.js
36
Hello.js:
var hello = function () {
print("Hello Nashorn");
}
hello();

Java seen from Nashorn
37
var HashMap = Java.type('java.util.HashMap');
var map = new HashMap();
map.put('foo', 'foo1');
map.put('bar', 'bar1');
for each(var e in map.keySet()) print(e);
for each(var e in map.values()) print(e);

Nashorn seen from Java
38
import javax.script.*;
public class Nashorn {
public static void main (String[] args) {
ScriptEngineManager m = new ScriptEngineManager();
ScriptEngine e = m.getEngineByName("nashorn");
try {
e.eval("print('hello');"); }
catch (final ScriptException se) {
}
}
}

Thank you for your attention!
40

Java World, Java Trends, Java 8 and Beyond (iForum - 2014)

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