> ## Documentation Index
> Fetch the complete documentation index at: https://www.jetify.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Java

> In addition to installing the JDK, you'll need to install either the Maven or Gradle build systems in your shell.

In both cases, you'll want to first activate `devbox shell` before generating your Maven or Gradle
projects, so that the tools use the right version of the JDK for creating your project.

[**Example Repo**](https://github.com/jetify-com/devbox/tree/main/examples/development/java)

## Adding the JDK to your project[​](#adding-the-jdk-to-your-project "Direct link to Adding the JDK to your project")

`devbox add jdk binutils`, or in your `devbox.json`

```json theme={null}
  "packages": [
    "jdk@latest",
    "binutils@latest"
  ]
```

This will install the latest version of the JDK. To find other installable versions of the JDK, run
`devbox search jdk`.

Other distributions of the JDK (such as OracleJDK and Eclipse Temurin) are available in Nixpkgs, and
can be found using
[NixPkg Search](https://search.nixos.org/packages?channel=22.05\&from=0\&size=50\&sort=relevance\&type=packages\&query=jdk#)

## Gradle[​](#gradle "Direct link to Gradle")

[**Example Repo**](https://github.com/jetify-com/devbox/tree/main/examples/development/java/gradle/hello-world)

Gradle is a popular, multi-language build tool that is commonly used with JVM projects. To setup an
example project using Gradle, follow the instructions below:

1. Create a project folder: `my-project/` and call `devbox init` inside it. Then add these packages:
   `devbox add jdk` and `devbox add gradle`.
   * Replace `jdk` with the version of JDK you want. Get the exact nix-pkg name from
     `search.nixos.org`.

2. Then do `devbox shell` to get a shell with that `jdk` nix pkg.

3. Then do: `gradle init`
   * In the generated `build.gradle` file, put the following text block:

     ```gradle theme={null}
     /* build.gradle */
     apply plugin: 'java'
     apply plugin: 'application'

     /* Change these versions to the JDK version you have installed */
     sourceCompatibility = 17
     targetCompatibility = 17
     mainClassName = 'hello.HelloWorld'

     jar {
         manifest {
           /* assuming main class is in src/main/java/hello/HelloWorld.java */
             attributes 'Main-Class': 'hello.HelloWorld'
         }
     }
     ```

   * While in devbox shell, run `echo $JAVA_HOME` and take note of its value.

   * Create a `gradle.properties` file like below and put value of `$JAVA_HOME` instead of
     \<JAVA\_HOME\_VALUE> in the file.

     ```properties theme={null}
     /* gradle.properties */
     org.gradle.java.home=<JAVA_HOME_VALUE>
     ```

4. `gradle build` should compile the package and create a `build/` directory that contains an
   executable jar file.

5. `gradle run` should print "Hello World!".

6. Add `build/` to `.gitignore`.

An example `devbox.json` would look like the following:

```json theme={null}
{
  "packages": ["gradle", "jdk", "binutils"],
  "shell": {
    "init_hook": null
  }
}
```

## Maven[​](#maven "Direct link to Maven")

[**Example Repo**](https://github.com/jetify-com/devbox/tree/main/examples/development/java/maven/hello-world)

Maven is an all-in-one CI-CD tool for building testing and deploying Java projects. To setup a
sample project with Java and Maven in devbox follow the steps below:

1. Create a dummy folder: `dummy/` and call `devbox init` inside it. Then add the nix-pkg:
   `devbox add jdk` and `devbox add maven`.
   * Replace `jdk` with the version of JDK you want. Get the exact nix-pkg name from
     `search.nixos.org`.
2. Then do `devbox shell` to get a shell with that `jdk` nix pkg.
3. Then do:
   `mvn archetype:generate -DgroupId=com.devbox.mavenapp -DartifactId=devbox-maven-app -DarchetypeArtifactId=maven-archetype-quickstart -DarchetypeVersion=1.4 -DinteractiveMode=false`
   * In the generated `pom.xml` file, replace java version in `<maven.compiler.source>` with the
     specific version you are testing for.
4. `mvn package` should compile the package and create a `target/` directory.
5. `java -cp target/devbox-maven-app-1.0-SNAPSHOT.jar com.devbox.mavenapp.App` should print "Hello
   World!".
6. Add `target/` to `.gitignore`.

An example `devbox.json` would look like the following:

```json theme={null}
{
  "packages": ["maven", "jdk", "binutils"],
  "shell": {
    "init_hook": null
  }
}
```

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