1# Java
2
3Java language support in Zed is provided by:
4
5- Zed Java: [zed-extensions/java](https://github.com/zed-extensions/java)
6- Tree-sitter: [tree-sitter/tree-sitter-java](https://github.com/tree-sitter/tree-sitter-java)
7- Language Server: [eclipse-jdtls/eclipse.jdt.ls](https://github.com/eclipse-jdtls/eclipse.jdt.ls)
8
9## Install OpenJDK
10
11You will need to install a Java runtime (OpenJDK).
12
13- macOS: `brew install openjdk`
14- Ubuntu: `sudo add-apt-repository ppa:openjdk-23 && sudo apt-get install openjdk-23`
15- Windows: `choco install openjdk`
16- Arch Linux: `sudo pacman -S jre-openjdk-headless`
17
18Or manually download and install [OpenJDK 23](https://jdk.java.net/23/).
19
20## Extension Install
21
22You can install by opening {#action zed::Extensions}({#kb zed::Extensions}) and searching for `java`.
23
24## Quick start and configuration
25
26For the majority of users, Java support should work out of the box.
27
28- It is generally recommended to open projects with the Zed-project root at the Java project root folder (where you would commonly have your `pom.xml` or `build.gradle` file).
29
30- By default the extension will download and run the latest official version of JDTLS for you, but this requires Java version 21 to be available on your system via either the `$JAVA_HOME` environment variable or as a `java(.exe)` executable on your `$PATH`. If your project requires a lower Java version in the environment, you can specify a different JDK to use for running JDTLS via the `java_home` configuration option.
31
32- You can provide a **custom launch script for JDTLS**, by adding an executable named `jdtls` (or `jdtls.bat` on Windows) to your `$PATH` environment variable. If this is present, the extension will skip downloading and launching a managed instance and use the one from the environment.
33
34- To support [Lombok](https://projectlombok.org/), the lombok-jar must be downloaded and registered as a Java-Agent when launching JDTLS. By default the extension automatically takes care of that, but in case you don't want that you can set the `lombok_support` configuration-option to `false`.
35
36Here is a common `settings.json` including the above mentioned configurations:
37
38```jsonc
39{
40 "lsp": {
41 "jdtls": {
42 "settings": {
43 "java_home": "/path/to/your/JDK21+",
44 "lombok_support": true,
45 },
46 },
47 },
48}
49```
50
51## Debugging
52
53Debug support is enabled via our [Fork of Java Debug](https://github.com/zed-industries/java-debug), which the extension will automatically download and start for you. Please refer to the [Debugger Documentation](https://zed.dev/docs/debugger#getting-started) for general information about how debugging works in Zed.
54
55To get started with Java, click the `edit debug.json` button in the Debug menu, and replace the contents of the file with the following:
56
57```jsonc
58[
59 {
60 "adapter": "Java",
61 "request": "launch",
62 "label": "Launch Debugger",
63 // if your project has multiple entry points, specify the one to use:
64 // "mainClass": "com.myorganization.myproject.MyMainClass",
65 //
66 // this effectively sets a breakpoint at your program entry:
67 "stopOnEntry": true,
68 // the working directory for the debug process
69 "cwd": "$ZED_WORKTREE_ROOT",
70 },
71]
72```
73
74You should then be able to start a new Debug Session with the "Launch Debugger" scenario from the debug menu.
75
76## Launch Scripts (aka Tasks) in Windows
77
78This extension provides tasks for running your application and tests from within Zed via little play buttons next to tests/entry points. However, due to current limitations of Zed's extension interface, we can not provide scripts that will work across Maven and Gradle on both Windows and Unix-compatible systems, so out of the box the launch scripts only work on Mac and Linux.
79
80There is a fairly straightforward fix that you can apply to make it work on Windows by supplying your own task scripts. Please see [this Issue](https://github.com/zed-extensions/java/issues/94) for information on how to do that and read the [Tasks section in Zeds documentation](https://zed.dev/docs/tasks) for more information.
81
82## Advanced Configuration/JDTLS initialization Options
83
84JDTLS provides many configuration options that can be passed via the `initialize` LSP-request. The extension will pass the JSON-object from `lsp.jdtls.settings.initialization_options` in your settings on to JDTLS. Please refer to the [JDTLS Configuration Wiki Page](https://github.com/eclipse-jdtls/eclipse.jdt.ls/wiki/Running-the-JAVA-LS-server-from-the-command-line#initialize-request) for the available options and values. Below is an example `settings.json` that would pass on the example configuration from the above wiki page to JDTLS:
85
86```jsonc
87{
88 "lsp": {
89 "jdtls": {
90 "settings": {
91 // this will be sent to JDTLS as initializationOptions:
92 "initialization_options": {
93 "bundles": [],
94 // use this if your zed project root folder is not the same as the java project root:
95 "workspaceFolders": ["file:///home/snjeza/Project"],
96 "settings": {
97 "java": {
98 "home": "/usr/local/jdk-9.0.1",
99 "errors": {
100 "incompleteClasspath": {
101 "severity": "warning",
102 },
103 },
104 "configuration": {
105 "updateBuildConfiguration": "interactive",
106 "maven": {
107 "userSettings": null,
108 },
109 },
110 "import": {
111 "gradle": {
112 "enabled": true,
113 },
114 "maven": {
115 "enabled": true,
116 },
117 "exclusions": [
118 "**/node_modules/**",
119 "**/.metadata/**",
120 "**/archetype-resources/**",
121 "**/META-INF/maven/**",
122 "/**/test/**",
123 ],
124 },
125 "referencesCodeLens": {
126 "enabled": false,
127 },
128 "signatureHelp": {
129 "enabled": false,
130 },
131 "implementationCodeLens": "all",
132 "format": {
133 "enabled": true,
134 },
135 "saveActions": {
136 "organizeImports": false,
137 },
138 "contentProvider": {
139 "preferred": null,
140 },
141 "autobuild": {
142 "enabled": false,
143 },
144 "completion": {
145 "favoriteStaticMembers": [
146 "org.junit.Assert.*",
147 "org.junit.Assume.*",
148 "org.junit.jupiter.api.Assertions.*",
149 "org.junit.jupiter.api.Assumptions.*",
150 "org.junit.jupiter.api.DynamicContainer.*",
151 "org.junit.jupiter.api.DynamicTest.*",
152 ],
153 "importOrder": ["java", "javax", "com", "org"],
154 },
155 },
156 },
157 },
158 },
159 },
160 },
161}
162```
163
164## See also
165
166[Zed Java Repo](https://github.com/zed-extensions/java)
167[Eclipse JDTLS Repo](https://github.com/eclipse-jdtls/eclipse.jdt.ls)