Java 8 is coming. It is happening right here. Developers of your favorite Java IDE are participating in shaping this long awaited milestone for the Java ecosystem: On time with the GA of Java 8, JDT will ship its first release with support for developing in Java 8. If you have a basic understanding of the new features in Java 8, come here and learn how the JDT team mastered the challenges of lifting the Eclipse Java IDE to the next language version. The main focus of this talk will be on lambda expressions, touching also some changes in the libraries that leverage lambda expressions. We will expose some examples demonstrating the complexity of the language and mention some caveats which should help you avoid some unpleasent surprises. We will demo how to get started using Java 8 in Eclipse and show the latest tool features for working with lambda expressions including new quick assists etc. Finally, we'll give a retrospective discussion of the situation of the JDT team, in terms of team changes, contributors, deadlines, interaction with expert groups, with the Eclipse community, and more.

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Srikanth Sankaran
IBM India
Stephan Herrmann
GK Software
Noopur Gupta
IBM India

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Java 8 features:
JSR335 - Project Lambda
 Lambda Expressions & Method References
 Extensions to
Overload resolution & Type inference
 Support for “code carrying” interface methods.
JSR308 - Type Annotations
JEP120 - Repeating Annotations
JEP118 - Method Parameter Reflection
JSR269 - Pluggable Annotation Processor API &
javax.lang.model API enhancements for Java 8

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LambdaExpression ::= LambdaParameters '->' LambdaBody
LambdaParameters -> BeginLambda LambdaParameterList
LambdaParameterList -> '(' FormalParameterListopt ')„
LambdaBody -> Expression
LambdaBody -> Block
I i = BeginLambda (x) -> { };

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Scanning + Parsing => Parse tree
+ Resolution => Resolved parse tree
+ Data/control flow analysis => Flow analyzed parse tree
+ Code generation => Class files.
() -> { throw new Exception(); } is void and value compatible.

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o Changes the very notion of a type.
o Some subsystems should view @NonNull String != @ReadOnly String
o while others should view them as being the same.
o Abstractions need to support either world view efficiently.
String is a String is a String

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Collectors.<Person,String,Integer>toMap(..)
Collectors.toMap(..)
Collector<String,Integer> coll = new MyCollector<>();

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 Recipe for disaster:
● implement java.util.List → compile against JRE 7 → OK
● upgrade to JRE 8 but compile as 1.7
 Undefined compiler behavior
● 1.7 compiler cannot handle default methods (from .class)
● exact answer depends on compiler implementation details
● there is no specification
● ecj and javac differ
● assimilation is difficult

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Enter
+Ctrl 1
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Enter
+Ctrl 1

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Enter
+Ctrl 1

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Enter
+Ctrl 1

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Lambda Expression:
Method Reference:

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Demo
Examples:

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Far too risky to
cram late into 8
(Nov 2013)

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List <: List<String> ?
Raw types

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“Problem detected during type inference: ...”

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Dramatis personæ - The usual suspects
Jay Arthanareeswaran
Deepak Azad
Shankha Banerjee
Anirban Chakarborty
Vikas Chandra
Noopur Gupta
Ayushman Jain
Manju Mathew
Manoj Palat
Srikanth Sankaran
Sarika Sinha
Jesper S. Møller
Stephan Herrmann
Markus Keller
Dani Megert
Andy Clement
Steve Francisco
Michael Rennie
Olivier Thomann
Curtis Windatt
Walter Harley
David Williams

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