Java SE 8 New Features

1. Java 8 - New Features
NaveenHegde
Apr 2014

2. Java Version History
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1996 1998 2000 2002 2004 2006 2011
Java SE 8
Spider
2014
First release developed
under the Java
Community Process
Version 1.5 -> 5
To reflect level of
Maturity, Stability
J2SE -> Java SE
Dropped .0

3. • Java 5
– Generics, Autoboxing
– Enhanced For-Loop, VarArgs and more…
Recap - Major Feature Additions in
Java
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 Java 6
• Script Engine
• New I/O
• Jconsole, profiler & debug interface (JVMPI, JVMDI)
 Java 7
• Strings in Switch, Catch Multiple-Exceptions
• Try-with-Resource, Type Interface
• JVM Support for Non-Java Languages

4. • Lambda Expressions
• Streams Facility
• Date-Time Library
• permgen replaced by Metaspace
• Type Annotations and Repeating Annotations
• jdbc-odbc bridge removed
• New utilities to improve Performance, Scalability
Java SE 8 New Features at glance
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5. • Treat functionality as method argument (code as data)
• Avoid anonymous inner class which seem excessive & unclear
• Cleaner way to implement Functional Interfaces
• Used to create anonymous methods
Lambda Expressions
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Parameter(s)
Body
single expression or statement block
Lambda Expression Syntax
Sample Code for “Sorting persons array by Age”
Java compiler determines Lambda Expr Type using new “Target Typing” mechanism

6. • In Swing, JavaFX, Often, event handler interfaces are
functional interfaces
• Lambda expressions can best replace anonymous classes
created for keyboard actions, mouse actions etc
Using Lambda Expression in GUI
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7. • Creation of compact, easy-to-read lambda expressions
• Use it with Lambda Expresions for
– Encapsulate a single unit of behavior and pass it to other code
– Create simple instance of a functional interface
Method References
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Method Reference Type Example
to a static method Person::compareByAge
to an instance method of a particular object myComparator::compareByName
to a method of arbitrary type instance String::compareToIgnoreCase
to a constructor HashSet::new

8. • Ability to add default implementation in interfaces
• No impact on already existing implementations
Default Interface Method
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 Extending Interfaces That Contain Default Methods
• Not mention default method -> inherits the default
• Redeclare the default method -> makes it abstract.
• Redefine the default method -> overrides it
Interface with all default methods is like an Adapter

9. • New package for filter/map/reduce transformations on streams
• Includes many useful built in aggregate operations
java.util.stream.*
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int ave = Arrays.stream(personArr)
.filter(b -> b.getGender() == Gender.MALE)
.mapToDouble(Person::getSalary)
.average()
.getAsDouble();
‘persons’ is a Collection<Person>
 Generating Streams
• Collection objects: via the stream() and parallelStream() methods
• Array elements: via Arrays.stream(Object[])
• Lines of File : BufferedReader.lines()
• Streams of random numbers : Random.ints()

10. • No storage
– A stream is not a data structure that stores elements
– it conveys elements from a source (Array,Collection,IO Channel
etc) through a pipeline of computational operations
– stream operation produces a result without modifing its source
• Functional in nature
– Enable Functional way of Working with Databases – Easy and elegant
• Parallelism
– Streams facilitate parallel execution by reframing the computation as a
pipeline of aggregate operations
• Consumable
– The elements are visited only once during the life of a stream.
– new stream must be generated to revisit the same elements
Why use Streams?
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11. • JavaSE 6
– Date
– Calendar
– DateFormat
– TimeZone
Date-Time Packages
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 Java 8
formatter=DateTimeFormatter.ofPattern("yyyy MM dd");
String text = date.toString(formatter);
LocalDate date = LocalDate.parse(text, formatter)
ChronoUnit.DAYS.between(t1, t2)

12. • Motive
– Solve the common scalability problem of “Maintaining a single count, sum,
etc. that is updated by many threads”
• How?
– Internally employ contention-reduction techniques
– Provides huge throughput improvements as compared to Atomic variables
• Classes
– DoubleAccumulator
 One or more variables that together maintain a running double value updated using a
supplied function.
– DoubleAdder
 One or more variables that together maintain an initially zero double sum.
– LongAccumulator
– LongAdder
Scalable-Updatable variable support
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13. • Streams & Lambda expression based new methods
– forEach methods
 forEach, forEachKey, forEachValue, and forEachEntry
– search methods
 search, searchKeys, searchValues, and searchEntries
– reduction methods
 reduce, reduceToDouble, reduceToLong …
ConcurrentHashMap Enhancements
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-> ConcurrentHashMaps (and classes built from them) are more useful as cache

14. • Interfaces
– CompletionStage<T>: A stage of a possibly asynchronous computation
• Classes
– CompletableFuture<T>: A Future that may be explicitly completed
 May be used as a CompletionStage,
 Supports actions that trigger upon its completion
– CountedCompleter<T>: A ForkJoinTask with a completion Action
 Action is triggered when there are no remaining pending actions
– ConcurrentHashMap.KeySetView<K,V>:
 A view of ConcurrentHashMap as a Set of keys
 Additions may optionally be enabled by mapping to a common value
New Additions to java.util.concurrent
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15. • Arrays.parallelSort()
– Parallel merge-sort algorithm technique using ForkJoinPool
• Bulk Data Operations for Collections
• Base64 Encoding & Decoding support
– New Classes
 Base64, Base64.Decoder, Base64.Encoder
– Eg Applications of use
 Multipurpose Internet Mail Extensions (MIME)
 encode passwords for HTTP headers
Utils
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16. • StampedLock
– A capability-based lock with three modes for controlling access
 1) Reading 2) Writing 3) Optimistic Reading
– Lock acquisition methods return a stamp
– Stamp represents and controls access with respect to a lock state
– Designed for the development of thread-safe components
– Not re-entrant
• ForkJoinPool (since java7)
– ExecutorService for running ForkJoinTasks
– A static commonPool() is added to reduce resource usage
 Default pool appropriate for most applications
– ForkJoinPool differs from other kinds of ExecutorService
 Mainly by virtue of employing work-stealing
 All threads in the pool attempt to find and execute subtasks created by other tasks or external
clients like management and monitoring operations
Miscellaneous
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17. • Repeating Annotations
– provide the ability to apply the same annotation type more than once to
the same declaration
• Type Annotations
– provide the ability to apply an annotation anywhere a type is used, not
just on a declaration.
– Used with a pluggable type system,
– this feature enables improved type checking of your code
Annotations
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18. • Motive
– Eliminate need for ‘MaxPermSize’ tuning (one of the reasons for OOM error)
– Improve GC performance
• Removal of PermGen
– Most allocations for the class metadata is done out of native memory
– Some miscellaneous data has been moved to the Java heap
– klasses that were used to described class metadata have been removed
– Metaspace is Non-contigeous to heap
– A garbage collection may be induced to collect dead classloaders and classes. The
first garbage collection will be induced when the class metadata usage reaches
MaxMetaspaceSize
PermGen replaced by Metaspace
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Heap
NewGen
Survivor Space
OldGen
PermGen
Heap
NewGen
Survivor Space
OldGen
Metaspace Native
Mem
PermGen=Region{
Class Metadata, Hierarchy info,
Constant Pool, Bytecode …}
No more “OutOfMemoryError:
PermGen space”

19. • Defines subsets of JRE for devices that have limited
storage capacity
• Match Application Functional needs closely
Compact Profiles
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Security(E) JMX Instrumentation XML JAXP (E)
JDBC RMI XML JAXP
Core Networking IO Collections
Scripting Regex JNDI Reflection
Profile1
Profile2
CompactProfile3
FullSEAPI
Swing Beans Sound Image I/O Java 2D
CORBA JNI IDL Print Service AWT

20. • Lightweight, high-performance script engine
• Implemented in Java by Oracle
• Replaces Mozilla Rhino JavaScript interpreter
– Rhino compiled all JavaScript code to bytecode in generated class files.
– Compared to C implementation of Javascript run with JIT compilation,
Rhino had better performance
– Rhino had memory leak since most JVMs don’t clean unused classes
• Nashorn
– compiles scripts in memory and passes bytecode directly to JVM
Nashorn Javascript Engine
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21. • Enriched 3D Graphics features
• New SwingNode class
– SwingNode - enables embedding Swing content into JavaFX
– ScheduledService - allows to automatically restart the service
• Enhanced text support
– Hindi and Thai controls
– New Styles - bi-directional text, multi-line etc
• Now Compatible with ARM platforms
Java FX
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22. • The JDBC-ODBC Bridge has been removed
– Reason
 The JDBC-ODBC Bridge had been non-supported product
 Was provided with only selected JDKs and not included in JRE
– Alternate recommendation
 Use a JDBC driver provided by the database vendor
 If it was in use to with MS Access DB or Excel spreadsheet etc, could be replaced by
pure java DB like H2, Java DB etc.
• JDBC 4.2
– Minor enhancements to JDBC to improve usability and portability
• JDK 8 includes Java DB 10.10
– a version of the Apache Derby database (since Java 5)
JDBC
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23. • URLPermission Represents permission to access
– a resource defined by url
– for a given set of user-settable request methods and request headers
• URLPermission(String url_name, String actions)
– name of the permission is the url string
 http://www.oracle.com/a/b/*
– actions string is a concatenation of the request methods and headers
 "POST,GET,DELETE“
 "POST,GET:Header1,Header2“
• Examples of Path Matching
– public boolean implies(Permission p)
HTTP URL Permission
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This’s path P’s path Matches /implies
/a/b/* /a/b/c Yes
/a/b/* /a/b/c/d No
/a/b/- /a/b/c/d/e Yes

24. • KeyStore enhancements
– new Domain KeyStore type java.security.DomainLoadStoreParameter
– new command option - importpassword for the keytool utility
• New variant of AccessController.doPrivileged
– enables code to assert a subset of its privileges, without preventing the
full traversal of the stack to check for other permissions
• Support for
– Stronger algorithms for password-based encryption
– AEAD algorithms
– SHA-224 Message Digests
– rcache Types in Kerberos 5 Replay Caching
Security
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25. • Leverage CPU Instructions for AES Cryptography
– Intel Westmere hardware (2010 or newer) has instruction set to
support AES (Advanced Encryption Standard)
– Syntax: -XX:+UseAES -XX:+UseAESIntrinsics
• JMC 5.3
– JMC (Originally developed by JRockit) is an advanced set of tools that
enabling efficient JVM monitoring & profiling
– JMC is bundled with the HotSpot JVM starting from Java SE 7u40
HotSpot VM
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26. • New Commands
– Jjs – invoke Nashorn java script engine
– Java – can launch JavaFX
– Jdeps - analyze class files
• Pack200
– Pack200 support for Constant Pool Entries and New Bytecodes
Tools
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27. Thank You
END
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