Java SE 8 is the most significant expansion of the Java programming model yet and Eclipse Luna (R 4.4) has been reloaded to be ready for Java 8. Get a glimpse of goodies provided by Eclipse as part of the Java 8 support in this article: https://www.eclipse.org/community/eclipse_newsletter/2014/june/article1.php

1. Eclipse Luna: Ready for JavaTM
8
Java SE 8 is the most significant expansion of the Java programming model yet and Eclipse
Luna (R 4.4) has been reloaded to be ready for Java 8.
Here is a glimpse of goodies provided by Eclipse as part of the Java 8 support:
UNDER THE HOOD
The Java tooling in Eclipse has its own compiler implementation which not only generates the
class files, but also produces a Java document model which forms the basis for implementing a
large number of tooling features.
Preparing Eclipse to be Java 8 ready involved a series of steps filled with technical and process
challenges to support all the incremental updates of the Java Language Specification: the
parser, compiler and indexer were evolved, the new type inference engine was developed,
debugger evaluation support was added, major updates were introduced in DOM AST and Java
model APIs, existing functionality was retooled to blend with the new language features and
new functionality was added to make your experience with Java 8 more pleasant.

2. HIGHLIGHTS
 The Eclipse Compiler for Java (ECJ) implements all the new Java 8 language
enhancements.
 Quickly change a project to be compatible with Java 8:
 Convert anonymous class creations to lambda expressions (and back) by invoking the
Quick Assists (Ctrl+1):
 Convert to lambda expression
 Convert to anonymous class creation
Or invoke Source > Clean Up... to migrate all your existing code to use lambda
expressions where applicable:

3. The functionality to migrate anonymous classes to lambda expressions has been made
intelligent to make sure that only valid code is generated. It ignores the conversion
where it is not possible, and it even updates the variable names to prevent name
conflicts with variables from an enclosing scope. For example, the conversion is not
performed if the anonymous class does not implement a functional interface,
implements a functional interface with a generic abstract method, contains additional
members, contains unqualified ‘this’ or ‘super’ references etc.
 Change lambda expression’s body to block or expression by invoking the Quick Assists
(Ctrl+1):
 Change body expression to block
 Change body block to expression
 The new concise syntax of lambda expressions and method references looks nice, but it
may not be so intuitive for developers due to inferred target types, inferred parameter
types, various shorthand syntaxes for method and constructor references etc. This is
where Eclipse helps you to become more productive while writing or understanding
programs with Java 8 constructs.
 To view the method implemented by the functional interface instances, just hover
on:

4. - ‘->’ in a lambda expression
- ‘::’ in a method reference
 To navigate to the functional method declaration, hold Ctrl, move the mouse pointer
over '->' or '::', and click the hyperlink:
- In a lambda expression:
- In a method reference:
 You can control the formatting of lambda expressions via new Formatter options:
 Configure the position of braces in lambda body
 Configure the whitespace before and after the arrow operator
 You can search for method reference expressions in Java Search by limiting the match
location of methods or constructors to method references:

5.  The Type Hierarchy view and Quick Hierarchy (Ctrl+T) (on the functional interface and
its abstract method) show lambda expressions also as implementations of the functional
interface:
 Eclipse also provides Content Assist (Ctrl+Space) support for method references:

6.  Quickly identify the abstract (A), default (D) and static (S) methods of an interface in
views like Outline, Search, Type Hierarchy, Quick Outline / Hierarchy with the new icon
adornments:
 The Java debugger supports breakpoints in lambda expressions and evaluation or
inspection in the context of interface methods:
 JEP 118 provides the option to store information about method parameters in class files
when a programmer opts for it. This information is then usable via reflection. In 1.8
compliance mode, you can enable this with the new preference option:

7.  Java tooling features like Refactorings, Source actions, Content assist (Ctrl+Space), Mark
occurrences, Expand selection, Reconciler, Annotation Processor support etc. have been
updated to work well with the new Java 8 features. Here is an example of the extract
method support:
 JSR 308 introduces Type Annotations in Java 8, and Eclipse provides the support for
type annotations based static null analysis by shipping a set of nullness annotations as
version 2.0.0 of the org.eclipse.jdt.annotation bundle. With these annotations, compile
time type checking is possible to ensure that the specified null constraints are not

8. violated and all possible NullPointerExceptions are reported (active if annotation-based
null analysis is enabled in Java Compiler > Errors/Warnings preferences):
This supports API designers to create better interfaces with stricter rules about what can
be passed to and returned from an API:
 The Eclipse Compiler for Java (with its new Java 8 type inference engine) has also been
verified to successfully build major projects like JRE8, OpenJFX and Eclipse SDK (~250
projects).