Latest version that supports Java8

[jakDev003]

Hello I am trying to get JDTLS working with Helix and Java 8. I tried the latest version but the logs are saying I need Java 17 or later. I need to stick with Java 8 due to that being what version my company is using still.....sigh...... so what version JDTLS can I use?

[fbricon]

Java 17 is required to run the JDT.LS server. But then you can use Java 1.8 to compile your project

[jakDev003]

Awesome so if I understand correctly I will need to both on my system? How can I run them concurrently? I would think setting JAVA_HOME would be an issue but I am very new to Java

[fbricon]

Yes. you need both. If you use sdkman for instance, jdt.ls should be able to automatically discover all installed java versions and pick 1.8 for your project. Else you'd have to configure something like that in Helix (I have no idea how Helix config works):

"java.configuration.runtimes": [
  {
    "name": "JavaSE-1.8",
    "path": "/path/to/jdk-8",
  }
]

JAVA_HOME could be used to set Java 17 to run jdt.ls, but Helix might have a way to set a different, specific JDK specific to jdt.ls, again I have no idea. I suggest you ask the Helix community for specific jdt.ls configuration.

[jakDev003]

Okay thank you so much! You have been so helpful. I reached out to the Helix chat for this but maybe you can answer this for me with a little additional information.

This is how I can set the config in Helix for JDTLS:

[language-server]
jdtls = { command = "jdtls" }
language-server = { command = "jdtls", args = [
  "-data", "/home/<USER>/.cache/jdtls/workspace"
  ]}

[[language]]
name = "java"
scope = "source.java"
injection-regex = "java"
file-types = ["java"]
roots = ["pom.xml", "build.gradle", ]
indent = { tab-width = 4, unit = "    " }
language-servers = [ "jdtls" ]

Does that give you enough information on how to tell helix to use one version over another?

I found this in the SDKMAN docs go get the current path of the JAVA version being used: https://sdkman.io/usage#home
I found this in the SDKMAN docs to change versions in a project directory but I would think I would need this to be Java 8 so when I run Maven it will use Java 8 or would Maven run what ever version it it told to in the run command? https://sdkman.io/usage#env-command

[jakDev003]

This is working for me. So I will post here for completeness.

[language-server]
jdtls = { command = "jdtls" }
language-server = { command = "sdk use java 21.0.4-tem && jdtls", args = [
  "-data", "/home/$USER/.cache/jdtls/workspace",
  "--jvm-arg=-javaagent:/usr/local/bin/lombok/lombok.jar"
]}

[[language]]
name = "java"
scope = "source.java"
injection-regex = "java"
file-types = ["java"]
roots = ["pom.xml", "build.gradle", ]
indent = { tab-width = 4, unit = "    " }
language-servers = [ "jdtls" ]