Java9/Features

The goal of this wiki page is to list down all the high level features that are being considered in Eclipse IDE for Java 9. The features shall include all the essential ones, nice-to-have and migration related features if any. Also, wherever possible please categorize the features as to which Eclipse component it falls under and if there are any dependencies. For tracking purposes, it would be ideal to highlight what state a particular feature is in. Possible states are Study, Requirement gathering, design, implementation, testing etc.

Compiler/Builder

Java 9 EE and JRE 9 (80%)

The IDE should support JavaSE9 as a valid EE and allow mapping a valid JRE/JDK 9.

Jimage support (100%)

JDK/JRE 9 now ship with jimage files that contain all the platform resources. The resolved classpath of a project with JRE 9 will now contain a single entry representing the bootmodule.jimage. All JDT components should now be adjusted to work with the jimage format. Goal is to have all existing tests pass with a jigsaw build.

Parser support for module-info.java (100%)

Grammar needs to be improved to accommodate new syntax changes in a module-info.java. The parser should take care of rejecting invalid code in a module-info with proper error. For instance, annotations are not supported in a module-info. Similarly it is not allowed to have regular code in a module-info.

Classfile support

The Classfile, ClassfileReader and friends should recognize a module-info.class and load the classfile content into a module, in a form useful to the resolution.

Code generation

Compiler module-info.java need to be compiled into .class, in the format specified by the VM specification.

Module resolution

The parser will take care of checking for incorrect syntax in a module-info.java. However, we still need a semantic analysis. Specifically, we might want to validate the following: That the exported packages and other entities specified actually exist in this module that all required modules are present in the current compilation context

Module System

Module system is eclipse's implementation of the module system specified in JEP 261. Module system is responsible for 1. keeping track of modules in the current compilation context. 2. Help LookupEnvironment in finding packages and Types according to the module dependencies and readability.

Batch compiler

JEP 261 specifies several new command line arguments. These need to be supported in ECJ. Notably -modulepath (shortly -mp) and -addexport.

Java Model

A big open question is where modules fits in the current Java model hierarchy. One way to go forward is to consider modules to be the following: 1. A kind of a package fragment root 2. A classpath location (IClasspathEntry, FileSystem.Classpath, ClasspathLocation etc.) This would mean that there could be multiple modules in a single Java projects. This is an open question that needs to be addressed (https://bugs.eclipse.org/bugs/show_bug.cgi?id=479483)

DOM AST

It needs to be seen where and how we want to use modules in the UI.

UI

Syntax highlighting

Editor should highlight the keywords in a module-info.java when opened in a Java editor.

Code completion

Code completion should work on completion of packages, types and module names in a module-info.java

Quick assist/fix

What kind of assistance do we want to provide here?

Classfile viewer

Being able to load/view module-info.class in the Classfile viewer.

Export Java project into JMOD?

A Java project with a module or a module in a Java project can be exported to a JMOD. It is still not clear whether this format is open for use by others.

Export Java projects into Jimage?

User should be able to select multiple modules in the workspace and export it to a jimage. It is still not clear whether this format is open for use by others.

Modules in the package explorer.

It needs to be decided how we want to represent the module in the package explorer.