The document discusses the evolution of the Java platform, including new features in Java SE 7 and Java SE 8. Some key changes in Java SE 7 include better integer literals, string switches, simplified generics using diamond operator, and automatic resource management. Java SE 8 will focus on invokedynamic for multi-language support on the JVM and method handles. The JVM specification defines the runtime environment independently of the Java programming language.

1. <Insert Picture Here>
The Future of the Java Platform:
Java SE 7 & Java SE 8
Terrence Barr
Senior Technologist, Mobile & Embedded Technologies

2. The preceding is intended to outline our general
product direction. It is intended for information
purposes only, and may not be incorporated into any
contract. It is not a commitment to deliver any
material, code, or functionality, and should not be
relied upon in making purchasing decisions.
The development, release, and timing of any
features or functionality described for Oracle’s
products remains at the sole discretion of Oracle.
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3. Agenda
Small
(Language) Project Coin (JSR 334)
Changes
Project Coin
Small Language Changes
The DaVinci Machine
Multiple Languages on the JVM
invokedynamic (JSR 292)
Library changes
Miscellaneous Updates
JSR 337:
Java SE 8 Release Contents
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4. Evolving the Language
From “Evolving the Java Language” - JavaOne 2005
• Java language principles
– Reading is more important than writing
– The language should not hide what is happening
– Code should do what it seems to do
– Simplicity matters
– Every “good” feature adds more “bad” weight
– Sometimes it is best to leave things out
• One language: with the same meaning everywhere
• No dialects
• We will evolve the Java language
• But cautiously, with a long term view
• “first, do no harm”
• Beware: Changes have many downstream implications (spec, tests,
implementation(s), tools, compatibility, future, ...)
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5. Java Standard Edition (Java SE) vs.
Java Development Kit (JDK)
• Java SE • Java Development Kit
• Definition of the software • Oracle's implementation of
platform Java SE
• Specification documents • Additional features not in
• Implementation the spec
• Test suite (TCK) • Tools and documentation
• Implemented by several • Deployment and
groups management capabilities
• Produced in the JCP • Performance features
• Produced in the OpenJDK
project
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6. Java SE 7
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7. Small
Section Divider
<Insert Picture Here>
(Language)
Changes
Project Coin
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8. Project Coin Constraints
• Small language changes
• Small in specification, implementation, testing
• No new keywords!
• Wary of type system changes
• Coordinate with larger language changes
– Project Lambda
– Modularity
• One language, one javac
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9. Better Integer Literal
• Binary literals
int mask = 0b101010101010;
• With underscores for clarity
int mask = 0b1010_1010_1010;
long big = 9_223_783_036_967_937L;
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10. String Switch Statement
• Today case label includes integer constants and
enum constants
• Strings are constants too (immutable)
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11. Discriminating Strings Today
int monthNameToDays(String s, int year) {
if("April".equals(s) || "June".equals(s) ||
"September".equals(s) ||"November".equals(s))
return 30;
if("January".equals(s) || "March".equals(s) ||
"May".equals(s) || "July".equals(s) ||
"August".equals(s) || "December".equals(s))
return 31;
if("February".equals(s))
...
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12. Strings in Switch
int monthNameToDays(String s, int year) {
switch(s) {
case "April": case "June":
case "September": case "November":
return 30;
case "January": case "March":
case "May": case "July":
case "August": case "December":
return 31;
case "February":
...
default:
...
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13. Simplifying Generics
• Pre-generics
List strList = new ArrayList();
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14. Simplifying Generics
• Pre-generics
List strList = new ArrayList();
• With Generics
List<String> strList = new ArrayList<String>();
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15. Simplifying Generics
• Pre-generics
List strList = new ArrayList();
• With Generics
List<String> strList = new ArrayList<String>();
List<Map<String, List<String>> strList =
new ArrayList<Map<String, List<String>>();
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16. Diamond Operator
• Pre-generics
List strList = new ArrayList();
• With Generics
List<String> strList = new ArrayList<String>();
List<Map<String, List<String>> strList =
new ArrayList<Map<String, List<String>>();
• With diamond (<>) compiler infers type
List<String> strList = new ArrayList<>();
List<Map<String, List<String>> strList =
new ArrayList<>();
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17. Simplifying Resource Use
InputStream in = new FileInputStream(src);
OutputStream out = new FileOutputStream(dest);
byte[] buf = new byte[8192];
int n;
while (n = in.read(buf)) >= 0)
out.write(buf, 0, n);
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18. Simplifying Resource Use
InputStream in = new FileInputStream(src);
OutputStream out = new FileOutputStream(dest);
try {
byte[] buf = new byte[8192];
int n;
while (n = in.read(buf)) >= 0)
out.write(buf, 0, n);
} finally {
in.close();
out.close();
}
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19. Simplifying Resource Use
InputStream in = new FileInputStream(src);
try {
OutputStream out = new FileOutputStream(dest);
try {
byte[] buf = new byte[8192];
int n;
while (n = in.read(buf)) >= 0)
out.write(buf, 0, n);
} finally {
out.close();
}
} finally {
in.close();
}
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20. Automatic Resource Management
try (InputStream in = new FileInputStream(src),
OutputStream out = new FileOutputStream(dest))
{
byte[] buf = new byte[8192];
int n;
while (n = in.read(buf)) >= 0)
out.write(buf, 0, n);
}
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21. Exceptions Galore
try {
...
} catch(ClassNotFoundException cnfe) {
doSomething(cnfe);
throw cnfe;
} catch(InstantiationException ie) {
log(ie);
throw ie;
} catch(NoSuchMethodException nsme) {
log(nsme);
throw nsme;
} catch(InvocationTargetException ite) {
log(ite);
throw ite;
}
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22. Multi-Catch
try {
// Reflective operations calling Class.forName,
// Class.newInstance, Class.getMethod,
// Method.invoke, etc.
} catch (final ClassCastException e) {
doSomething(e);
throw e;
} catch(final InstantiationException |
NoSuchMethodException |
InvocationTargetException e) {
log(e);
throw e;
}
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23. More Precise Rethrow
try {
// Reflective operations calling Class.forName,
// Class.newInstance, Class.getMethod,
// Method.invoke, etc.
} catch(final ReflectiveOperationException e) {
//e means any of the subtype thrown from try {}
log(e);
ReflectiveOperationException
throw e;
}
ClassNotFoundException
InstantiationException
NoSuchMethodException
InvocationTargetException
http://download.java.net/jdk7/docs/api/java/lang/ReflectiveOperationException.html23
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24. The DaVinci Machine Project
JSR 292
A multi-language renaissance for the JVM
openjdk.java.net/projects/mlvm
● Dynamic Invocation
● InvokeDynamic bytecode
● Method Handles
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26. JVM Architecture
• Stack based
• Push operand on to the stack
• Instructions operates by popping data off the stack
• Pushes result back on the stack
• Data types
• Eight primitive types, objects and arrays
• Object model – single inheritance with interfaces
• Method resolution
• Receiver and method name
• Statically typed for parameters and return types
• Dynamic linking + static type checking
• Verified at runtime
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27. JVM Specification
“The Java virtual machine knows
nothing about the Java
programming language, only of a
particular binary format, the class
file format.”
1.2 The Java Virtual Machine Spec.
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28. Languages Running on the JVM
Tea
Zigzag JESS Jickle iScript
Modula-2 Lisp
Correlate Nice
CAL
JudoScript
JavaScript
Simkin Drools Basic
Icon Groovy Eiffel
v-language Pascal Luck
Prolog Mini
Tcl PLAN Hojo
Rexx Jython Scala
Funnel
Tiger Anvil Yassl Oberon
FScript
E Smalltalk
Logo
Tiger JHCR JRuby
Ada G Scheme
Clojure
Phobos
Processing WebL Dawn TermWare
Sather
Sleep
LLP Pnuts Bex Script
BeanShell Forth PHP
C#
Yoix SALSA ObjectScript
Piccola
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29. Method Calls
● Calling a method is cheap
(VMs can even inline!)
● Selecting the right target
method can be expensive
● Static languages do most of their method selection at
compile time
● Single-dispatch on receiver type is left for runtime
● Dynamic languages do almost none at compile time
● But it would be nice to not have to re-do method selection
for every single invocation
● Each Language has its own
ideas about linkage
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30. InvokeDynamic Bytecode
• JVM currently has four ways to invoke method
• Invokevirtual, invokeinterface, invokestatic, invokespecial
• All require full method signature data
• InvokeDynamic will use method handle
• Effectively an indirect pointer to the method
• When dynamic method is first called bootstrap code
determines method and creates handle
• Subsequent calls simply reference defined handle
• Type changes force a re-compute of the method
location and an update to the handle
• Method call changes are invisible to calling code
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31. Library
Changes
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32. New I/O 2 (NIO2) Libraries
JSR 203
• Original Java I/O APIs presented challenges for
developers
• Not designed to be extensible
• Many methods do not throw exceptions as expected
• rename() method works inconsistently
• Developers want greater access to file metadata
• Java NIO2 solves these problems
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33. Java NIO2 Features
• Path is a replacement for File
• Biggest impact on developers
• Better directory support
• list() method can stream via iterator
• Entries can be filtered using regular expressions in API
• Symbolic link support
• Two security models (POSIX, ACL based on NFSv4)
• java.nio.file.Filesystem
• interface to a filesystem (FAT, ZFS, Zip archive, network, etc)
• java.nio.file.attribute package
• Access to file metadata
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34. Concurrency APIs
• JSR166y
• Update to JSR166x which was an update to JSR166
• Adds a lightweight task framework
• Also referred to as Fork/Join
• Uses ParallelArray
• Greatly simplifies use of many cores/processors for tasks that
can easily be separated
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35. Client Libraries
• Nimbus Look and Feel
• Platform APIs for shaped and translucent windows
• JLayer (formerly from Swing labs)
• Optimized 2D rendering
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36. Nimbus Look and Feel
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37. JLayer component
Easy enrichment for Swing components
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38. JLayer component
The universal decorator
• Transparent decorator for a Swing component
• Controls the painting of its subcomponents
• Catches all input and focus events for the whole hierarchy
// wrap your component with JLayer
JLayer<JPanel> layer = new JLayer<JPanel>(panel);
// custom ui provides all extra functionality
layer.setUI(myLayerUI);
// add the layer as usual component
frame.add(layer);
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39. Miscellaneous Updates
• Security
• Eliptic curve cryptography
• TLS 1.2
• JAXP 1.4.4 (Java API for XML processing)
• JAX-WS 2.2 (Java API for XML Web Services)
• JAXB 2.2 (Java Architecture for XML Binding)
• ClassLoader architecture changes
• close() for URLClassLoader
• Javadoc support for CSS
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40. Platform Support
• Windows (x86)
• Linux (x86)
• Redhat
• Ubuntu
• Solaris (x86)
• New: Apple OSX (x86)
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41. Java SE 8
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42. Java SE 8
Project Jigsaw
Modularising the Java Platform
Project Lambda (JSR 335)
Closures and more
Better support for multi-core processors
More Project Coin
Small Language Changes
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43. The Modular Java Platform
• Enables escape from “JAR Hell”
– Eliminates class path
– Package modules for automatic download & install
– Generate native packages – deb, rpm, ips, etc
• Enables significant performance improvements
– Incremental download → fast classloading
– Optimise module content during installation
• Platform scalability – down to small devices
– Well-specified SE subsets can fit into small devices
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44. module-info.java
Entry point Module name
Version
module com.foo @ 1.0.0 {
class com.foo.app.Main
requires org.bar.lib @ 2.1-alpha;
requires edu.baz.util @ 5.2_11;
provides com.foo.app.lib @ 1.0.0;
}
Dependency
Virtual module
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45. Project Lambda
Closures and more
openjdk.java.net/projects/lambda
● Lambda expressions
● SAM conversion with target typing
● Method references
● Library enhancements for internal iteration
● Default methods for interface evolution
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46. Hypothetical Internal Iteration
double highestScore = students
.filter(new Predicate<Student>() {
public boolean isTrue(Student s) {
return s.gradYear == 2010;
}})
.map(new Extractor<Student,Double>() {
public Double extract(Student s) {
return s.score;
}})
.max();
• Not inherently serial
– students traversal not determined by developer
– Looks like a functional language
• Anonymous inner class!
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47. Introducing Lambda Expressions
double highestScore = students
.filter(#{ Student s -> s.gradYear == 2010 })
.map(#{ Student s -> s.score })
.max();
• Lambda expressions introduced with #
– Signal to the JVM to defer execution of the code
– Body may be an expression
• Lambda expression are not syntactic sugar for
anonymous inner class
– Implemented with MethodHandle from JSR-292
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48. Roadmaps Are Approved!
• JSRs approved by JCP
– JSR 334: Small enhancements to the Java language
– JSR 335: Lambda expressions for the Java language
– JSR 336: Java SE 7 Release Contents
– JSR 337: Java SE 8 Release Contents
• OpenJDK Releases in 2011 & 2012
– Committed Features List for 2011:
• openjdk.java.net/projects/jdk7/features
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49. Conclusions
• Java SE 7
• Incremental changes
• Evolutionary, not revolutionary
• Good solid set of features to make developers life easier
• Java SE 8
• Major new features: Modularisation and Closures
• More smaller features to be defined
• Java Evolution Continues
• Grow and adapt to the changing world of IT
• Oracle and its partners are committed to a vibrant and
evolving Java ecosystem
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