docs: Java extension settings (#19113)

Co-authored-by: Peter Tripp <peter@zed.dev>

docs/src/languages/java.md

@@ -1,6 +1,203 @@
 # Java
 
-Java language support in Zed is provided the [zed Java extension](https://github.com/zed-extensions/java).
+There are two extensions that provide Java language support for Zed:
-Report issues to: [https://github.com/zed-extensions/java/issues](https://github.com/zed-extensions/java/issues)
+
+- Zed Java: [zed-extensions/java](https://github.com/zed-extensions/java) and
+- Java with Eclipse JDTLS: [zed-java-eclipse-jdtls](https://github.com/ABckh/zed-java-eclipse-jdtls).
+
+Both use:
 
 - Tree Sitter: [tree-sitter/tree-sitter-java](https://github.com/tree-sitter/tree-sitter-java)
+- Language Server: [eclipse-jdtls/eclipse.jdt.ls](https://github.com/eclipse-jdtls/eclipse.jdt.ls)
+
+## Pre-requisites
+
+You will need to install both a Java runtime (OpenJDK) and Eclipse JDT Language Server (`eclipse.jdt.ls`).
+
+### Install OpenJDK
+
+- MacOS: `brew install openjdk`
+- Ubuntu: `sudo add-apt-repository ppa:openjdk-23 && sudo apt-get install openjdk-23`
+- Windows: `choco install openjdk`
+- Arch Linux: `sudo pacman -S jre-openjdk-headless`
+
+Or manually download and install [OpenJDK 23](https://jdk.java.net/23/).
+
+### Install JDTLS
+
+- MacOS: `brew install jdtls`
+- Arch: [`jdtls` from AUR](https://aur.archlinux.org/packages/jdtls)
+
+Or manually download install:
+
+- [JDTLS Milestone Builds](http://download.eclipse.org/jdtls/milestones/) (updated every two weeks)
+- [JDTLS Snapshot Builds](https://download.eclipse.org/jdtls/snapshots/) (frequent updates)
+
+## Extension Install
+
+You can install either by opening {#action zed::Extensions}({#kb zed::Extensions}) and searching for `java`.
+We recommend you install one or the other and not both.
+
+## Settings / Initialization Options
+
+See [JDTLS Language Server Settings & Capabilities](https://github.com/eclipse-jdtls/eclipse.jdt.ls/wiki/Language-Server-Settings-&-Capabilities) for a complete list of options.
+
+Add the following to your Zed Settings by launching {#action zed::OpenSettings}({#kb zed::OpenSettings}).
+
+### Zed Java Settings
+
+```json
+{
+  "lsp": {
+    "jdtls": {
+      "settings": {},
+      "initialization_options": {}
+      }
+    }
+  }
+}
+```
+
+### Java with Eclipse JDTLS settings
+
+```json
+{
+  "lsp": {
+    "java": {
+      "settings": {},
+      "initialization_options": {}
+    }
+  }
+}
+```
+
+## See also
+
+- [Zed Java Readme](https://github.com/zed-extensions/java)
+- [Java with Eclipse JDTLS Readme](https://github.com/ABckh/zed-java-eclipse-jdtls)
+
+### Support
+
+If you have issues with either of these plugins, please open issues on their respective repositories:
+
+- [Zed Java Issues](https://github.com/zed-extensions/java/issues)
+- [Java with Eclipse JDTLS Issues](https://github.com/ABckh/zed-java-eclipse-jdtls/issues)
+
+## Example Configs
+
+### Zed Java Classpath
+
+You can optionally configure the class path that JDTLS uses with:
+
+```json
+{
+  "lsp": {
+    "jdtls": {
+      "settings": {
+        "classpath": "/path/to/classes.jar:/path/to/more/classes/"
+      }
+    }
+  }
+}
+```
+
+#### Zed Java Initialization Options
+
+There are also many more options you can pass directly to the language server, for example:
+
+```json
+{
+  "lsp": {
+    "jdtls": {
+      "initialization_options": {
+        "bundles": [],
+        "workspaceFolders": ["file:///home/snjeza/Project"],
+        "settings": {
+          "java": {
+            "home": "/usr/local/jdk-9.0.1",
+            "errors": {
+              "incompleteClasspath": {
+                "severity": "warning"
+              }
+            },
+            "configuration": {
+              "updateBuildConfiguration": "interactive",
+              "maven": {
+                "userSettings": null
+              }
+            },
+            "trace": {
+              "server": "verbose"
+            },
+            "import": {
+              "gradle": {
+                "enabled": true
+              },
+              "maven": {
+                "enabled": true
+              },
+              "exclusions": [
+                "**/node_modules/**",
+                "**/.metadata/**",
+                "**/archetype-resources/**",
+                "**/META-INF/maven/**",
+                "/**/test/**"
+              ]
+            },
+            "referencesCodeLens": {
+              "enabled": false
+            },
+            "signatureHelp": {
+              "enabled": false
+            },
+            "implementationsCodeLens": {
+              "enabled": false
+            },
+            "format": {
+              "enabled": true
+            },
+            "saveActions": {
+              "organizeImports": false
+            },
+            "contentProvider": {
+              "preferred": null
+            },
+            "autobuild": {
+              "enabled": false
+            },
+            "completion": {
+              "favoriteStaticMembers": [
+                "org.junit.Assert.*",
+                "org.junit.Assume.*",
+                "org.junit.jupiter.api.Assertions.*",
+                "org.junit.jupiter.api.Assumptions.*",
+                "org.junit.jupiter.api.DynamicContainer.*",
+                "org.junit.jupiter.api.DynamicTest.*"
+              ],
+              "importOrder": ["java", "javax", "com", "org"]
+            }
+          }
+        }
+      }
+    }
+  }
+}
+```
+
+## Java with Eclipse JTDLS Configuration {#zed-java-eclipse-configuration}
+
+Configuration options match those provided in the [redhat-developer/vscode-java extension](https://github.com/redhat-developer/vscode-java#supported-vs-code-settings).
+
+For example, to enable [Lombok Support](https://github.com/redhat-developer/vscode-java/wiki/Lombok-support):
+
+```json
+{
+  "lsp": {
+    "java": {
+      "settings": {
+        "java.jdt.ls.lombokSupport.enabled:": true
+      }
+    }
+  }
+}
+```