Contributions are essential for keeping this extension great. We try to keep it as easy as possible to contribute changes and we are open to suggestions for making it even easier. There are only a few guidelines that we need contributors to follow.

vscode-java vs eclipse.jdt.ls

vscode-java is a Visual Studio Code extension that uses a language server for its Java language smartness. Usually vscode-java features depend on the Eclipse ™ JDT Language Server, (a.k.a. eclipse.jdt.ls) and the contributions should be coordinated between the two repositories.

Background Info

For the whole language server to get up and running it requires two parts.

A) The Client Side (this repo): VSCode Java

B) The Server Side: JDT LS

Complete Setup Guide

The following will be a start to finish guide to get the entire language server up and running.

A) Client Side Setup

1. Install the required software:

   • latest Visual Studio Code
   • Node.js v18.17.1 (with npm 9.6.7) or higher

2. Fork and clone this repository

   Keep in mind the final directories will look like:

   PROJECT_FOLDER/
   	     |
     	     |--- vscode-java/
   	     |--- eclipse.jdt.ls/
   
   

3. cd vscode-java

4. Install the dependencies:

   $ npm install
   

5. (*Optional) Build a platform specific JRE:

   $ npm run download-jre
   

   You can also use the options --target and --javaVersion to build the specified JRE version for the specified target architecture.

B) Server Side Setup

This assumes that you are starting on the vscode-java directory

1. cd ..

2. Fork and clone the eclipse.jdt.ls repository

   Ensure the directory looks like:

   PROJECT_FOLDER/
   	     |
     	     |--- vscode-java/
   	     |--- eclipse.jdt.ls/
   
   

3. Build server

   $ cd ./vscode-java
   $ npm run build
   

If the eclipse.jdt.ls directory is not found as a sibling directory (see the desired hierarchy in the previous step), a snapshot of the language server will be downloaded instead.

To build the server using only the local eclipse.jdt.ls repository, use npm run build-server.

*Optional: You can run faster server builds during development by calling npm run fast-build-server script instead, this will build server binaries that are required by your host OS only. You can also use npm run watch-server which will build and place them on the extension for Java changes. These commands run Maven in offline mode, so you might need to run build-server at least once, to fetch all the dependencies.

This will build and place the binaries under the server folder. Alternately you can download and use the latest snapshot build from Eclipse ™ JDT Language Server project with the following

$ cd ../vscode-java
$ npm run download-server

Setting up the JDT Language Server

Below are the details about how to set up the JDT Language Server in different IDEs. Notice: You only need set up it once in any of your preferred IDE.

B-1) Setting up the JDT Language Server in VS Code

1. Please install Eclipse PDE support extension in your VS Code first. The PDE extension's home page provides more usage details about Reload Target Platform, Run JUnit Plug-in Test, Run Eclipse Application.

2. Open VS Code on the eclipse.jdt.ls folder. The PDE extension will work with Java extension together to automatically load the eclipse.jdt.ls project. Check the status of the language tools on the lower right corner. It should show ready (thumbs up) as the image below.

B-2) Setting up the JDT Language Server in Eclipse

1. In Eclipse, import a maven project:

   

   

   Select the eclipse.jdt.ls folder, then click yes/accept to all following prompts:

   

2. Now we need to use Tycho to download the dependencies, this will get rid of the errors.

   At the top right arrow it will say Set Target Platform, select that and continue.

   

   After it will change to Reload Target Platform select that:

   

3. Wait till the bottom right is done loading:

   

   once 100%:

   The errors should now be gone.

Running Everything

C) Run with a remote JDT language server

While developing the language server and the extension, you don't need to deploy the server every time to try out changes. Instead you can run the language server out of its Eclipse workspace. Currently we provide two kinds of connection modes between the extension and the language server.

C-1) The extension opens the connection first, and waits the language server to connect to it.

a) Launch Extension - Client Side

1. Open VSCode on the vscode-java folder

2. In the debug viewlet, run the launch Launch Extension - Remote Server

3. The extension will open a socket on port 3333 and will wait for the JDT language server to connect

b) Launch Debug Server - Server Side

• With the client side (vscode-java) running, you can start the remote server in your preferred IDE.

  • Start the remote server via VS Code.

  • Start the remote server via Eclipse.

• In the debug console of VSCode you can see if the connection was successful.

• When the server is running breakpoints can be reached and hot code replace can be used to make fixes without restarting the server.

• You can modify launch.json to use a different port:

  • Modify JDTLS_SERVER_PORT to specify the port the JDT LS server should connect to.

C-2) The language server opens the connection first, and waits the extension to connect to it.

• Start the language server via jdt.ls.socket-stream launch configuration in VS Code or Eclipse

• Start the extension via Launch Extension - JDTLS Client in VS Code

• You can modify launch.json to use a different port:

  • Modify JDTLS_CLIENT_PORT to specify the port VS Code should connect to.

C-3) Set location to a local copy of JDT-LS

This approach is mainly targeting developers of JDT-LS who want to test their changes in VSCode without having to rebuild vscode-java and to deal with the npm and vsix toolchains.

• Make sure a recent snapshot of vscode-java is installed in your VSCode instance (as of vscode-java 1.20.0)
• (Optionally) clear the workspace state: $ rm -r $HOME/.config/Code/User/workspaceStorage/0123456789abcdef01234567890abcdef/redhat.java/jdt_ws
• Start VSCode with the JDT_LS_PATH environment variable set to the local copy of JDT-LS you want to try: $ JDT_LS_PATH=$HOME/git/eclipse.jdt.ls/org.eclipse.jdt.ls.product/target/repository code

Most other options such as DEBUG_VSCODE_JAVA are still usable with this approach.

Sideloading

You can create a binary that you can sideload to your VS Code installation.

1. Fork and clone this repository

2. cd vscode-java

3. Install the dependencies:

   $ npm install
   

4. Optionally, follow the instruction to build the server.

5. See documentation on extension installation on ways to sideload or share.

Reporting issues

If you encounter a problem and know it is caused by eclipse.jdt.ls, then please open a bug report over there. In doubt, you can report issues in the vscode-java issue tracker.

Try to collect as much information as you can to describe the issue and help us reproduce the problem. Head over to the troubleshooting page to see how to collect useful logging information.

Certificate of Origin

By contributing to this project you agree to the Developer Certificate of Origin (DCO). This document was created by the Linux Kernel community and is a simple statement that you, as a contributor, have the legal right to make the contribution. See the DCO file for details.