Jump to: navigation, search

JDT UI/Java8

This page tracks the work in progress to add Java™ 8 support (mainly jsr308 "Type Annotations" and jsr335 "Lambda Expressions") into Eclipse JDT UI. See JDT Core/Java8 for the work in the JDT Core plug-ins.

Work areas

  • Annotations on types
    • Annotations that moved to another node in the AST
    • MethodDeclaration#thrownExceptions() -> thrownExceptionsTypes()
    • Annotations on Extra Dimensions
    • Render annotations in Javadoc hover/view. Do not render in Outline, etc. for now.
    • Refactoring dialogs that allow to modify types
  • Receiver parameter on instance methods and inner class constructors
  • Default Methods
  • Lambda Expressions
    • check code that walks the parent chain to find the enclosing Block or BodyDeclaration
  • Method References


  • The following lines must be added in all headers of modified files for Java™ 8 implementation:
 * This is an implementation of an early-draft specification developed under the Java
 * Community Process (JCP) and is made available for testing and evaluation purposes
 * only. The code is not compatible with any specification of the JCP.

  • Use the following @since tag on all newly added members: "3.9 BETA_JAVA8"

Things to remember/caveats

  • Goal of the first pass is to make Eclipse work with the new language features. For more advanced support (new quick fixes / refactorings / templates / ...), please file an enhancement request with the [1.8] tag.
  • Bugs that went into the BETA_JAVA8 branch should be RESOLVED/FIXED with Target Milestone "BETA_JAVA8" and the [1.8] tag in front of the summary.
  • For ASTNode changes:
    • Search for references to a changed AST Node and update code that relies on the concrete structure
    • Remember there are multiple ways to access AST node properties:
      • via getter/setter or List-valued accessor
      • via the StructuralPropertyDescriptor constant
      • for properties declared in an abstract class: via get*Property() instance method
    • Check references to superclasses of the changed/added node type. E.g. for IntersectionType, code that thinks it handles all known subtypes of Type needs to be adjusted.
    • Add new node types to switch or if-else-if statements
    • Think about cases where code could use StructuralPropertyDescriptors
  • Think about cases where new bindings can show up.

DOM AST node changes in JLS8

If everything is correct, then you should find these as references to ASTNode#unsupportedIn2_3_4() and #supportedOnlyIn2_3_4().

+AnnotatableType (abstract superclass):
  +annotations: List<Annotation> (also in subtypes PrimitiveType, ArrayType, SimpleType, QualifiedType, WildcardType)

  +annotations: List<Annotation>

  +parentheses: boolean
  +parameters: List<SingleVariableDeclaration> or List<VariableDeclarationFragment>
  +body: Block or Expression
  +resolveMethodBinding(): IMethodBinding

  +extraDimensions: List<ExtraDimension> (incl. annotations on extra dimensions)
  +receiverType: AnnotatableType
  +receiverQualifier: SimpleName
  -thrownExceptions: List<Name>
  +thrownExceptionTypes: List<Type>

  +varargsAnnotations: List<Annotation>

  +annotations: List<Annotation>

  +extraDimensions List<ExtraDimension> (also in subtypes SingleVariableDeclaration, VariableDeclarationFragment)

For JLS4, the changes were:

  +resources: List<VariableDeclarationExpression>

  +types: List<Type>


  • 'default' flag:
    • show in the UI?
    • update JdtFlags?
  • The ITypeBinding of a TYPE_USE-annotated expression (e.g. ClassInstanceCreation or reference to a variable) doesn't contain the TYPE_USE annotations. References to "String s" and "@NonEmpty String ns" have identical type bindings. Should TYPE_USE annotations show up in reference bindings? Note that for some expressions, the annotated type is not defined by jsr 308, e.g. for the conditional expression here:
@Deprecated @NonEmpty String s = new Random().nextBoolean()
	? new @NonEmpty String("hi")
	: new String();