This guide shows you how to set up an example Java project {% data reusables.codespaces.setting-up-project-intro %}

{% data reusables.getting-started.sign-in-dotcom %}

1. Go to https://github.com/microsoft/vscode-remote-try-java. {% data reusables.codespaces.use-this-template %}

When you create a codespace, your project is created on a remote virtual machine that is dedicated to you. By default, the container for your codespace has many languages and runtimes, including Java. It also includes a set of commonly used tools such as Gradle, Maven, git, wget, rsync, openssh, and nano.

{% data reusables.codespaces.customize-vcpus-and-ram %}

The default development container, or "dev container," for {% data variables.product.prodname_github_codespaces %} will allow you to work successfully on a Java project like vscode-remote-try-java. However, we recommend that you configure your own dev container to include all of the tools and scripts your project needs. This will ensure a fully reproducible environment for all {% data variables.product.prodname_github_codespaces %} users in your repository.

{% data reusables.codespaces.setup-custom-devcontainer %} {% data reusables.codespaces.command-palette-container %}

1. Type java and click the Java option. Other options are available if your project uses particular tools. For example, Java & PostgreSQL.

   

2. Choose the version of Java you want to use for your project. In this case, select the version marked "(default)."

   

3. Select the option to Install Maven and click OK.

   

4. A list of additional features you can install is displayed. We'll install Ant, the Java library and command-line tool for building applications. To install this feature, type ant, select Ant (via SDKMAN), then click OK.

   

{% data reusables.codespaces.overwrite-devcontainer-config %} {% data reusables.codespaces.details-of-devcontainer-config %}

// For format details, see https://aka.ms/devcontainer.json. For config options, see the
// README at: https://github.com/devcontainers/templates/tree/main/src/java
{
  "name": "Java",
  // Or use a Dockerfile or Docker Compose file. More info: https://containers.dev/guide/dockerfile
  "image": "mcr.microsoft.com/devcontainers/java:0-17",

  "features": {
    "ghcr.io/devcontainers/features/java:1": {
      "version": "none",
      "installMaven": "true",
      "installGradle": "false"
    },
    "ghcr.io/devcontainers-contrib/features/ant-sdkman:2": {}
  }

  // Use 'forwardPorts' to make a list of ports inside the container available locally.
  // "forwardPorts": [],

  // Use 'postCreateCommand' to run commands after the container is created.
  // "postCreateCommand": "java -version",

  // Configure tool-specific properties.
  // "customizations": {},

  // Uncomment to connect as root instead. More info: https://aka.ms/dev-containers-non-root.
  // "remoteUser": "root"
}

{% data reusables.codespaces.devcontainer-properties-1 %} {% data reusables.codespaces.devcontainer-properties-2 %}

{% data reusables.codespaces.additional-container-config %}

With your dev container configuration added and a basic understanding of what everything does, you can now make changes to customize your environment further. In this example, you'll add properties that will:

• Run a command, after the dev container is created, to create a new file.
• Automatically install two {% data variables.product.prodname_vscode_shortname %} extensions in this codespace.

1. In the devcontainer.json file, add a comma after the features property.

   "features": {
     "ghcr.io/devcontainers/features/java:1": {
       "version": "none",
       "installMaven": "true",
       "installGradle": "false"
     },
     "ghcr.io/devcontainers-contrib/features/ant-sdkman:2": {}
   },

2. Uncomment the postCreateCommand property and change its value to echo \"This file was added by the postCreateCommand.\" > TEMP.md.

   // Use 'postCreateCommand' to run commands after the container is created.
   "postCreateCommand": "echo \"This file was added by the postCreateCommand.\" > TEMP.md",

3. Uncomment the customizations property and edit it as follows to install the "Code Spell Checker" extension and the "Extension Pack for Java."

   // Configure tool-specific properties.
   "customizations": {
     // Configure properties specific to VS Code.
     "vscode": {
       // Add the IDs of extensions you want installed when the container is created.
       "extensions": [
         "streetsidesoftware.code-spell-checker",
         "vscjava.vscode-java-pack"
       ]
     }
   }

The devcontainer.json file should now look similar to this, depending on which image you chose:

// For format details, see https://aka.ms/devcontainer.json. For config options, see the
// README at: https://github.com/devcontainers/templates/tree/main/src/java
{
  "name": "Java",
  // Or use a Dockerfile or Docker Compose file. More info: https://containers.dev/guide/dockerfile
  "image": "mcr.microsoft.com/devcontainers/java:0-17",

  "features": {
    "ghcr.io/devcontainers/features/java:1": {
      "version": "none",
      "installMaven": "true",
      "installGradle": "false"
    },
    "ghcr.io/devcontainers-contrib/features/ant-sdkman:2": {}
  },

  // Use 'forwardPorts' to make a list of ports inside the container available locally.
  // "forwardPorts": [],

  // Use 'postCreateCommand' to run commands after the container is created.
  "postCreateCommand": "echo \"This file was added by the postCreateCommand.\" > TEMP.md",

  // Configure tool-specific properties.
  "customizations": {
    // Configure properties specific to VS Code.
    "vscode": {
      // Add the IDs of extensions you want installed when the container is created.
      "extensions": [
        "streetsidesoftware.code-spell-checker",
        "vscjava.vscode-java-pack"
      ]
    }
  }

  // Uncomment to connect as root instead. More info: https://aka.ms/dev-containers-non-root.
  // "remoteUser": "root"
}

{% data reusables.codespaces.save-changes %} {% data reusables.codespaces.rebuild-command %} {% data reusables.codespaces.rebuild-reason %}

After the dev container is rebuilt, and your codespace becomes available again, the postCreateCommand will have been run, creating a TEMP.md file, and the two extensions will be available for use.

1. Run the application by pressing F5.

2. If a "toast" notification message is displayed at the bottom right corner of {% data variables.product.prodname_vscode_shortname %}, asking whether you want to switch to standard mode, click Yes.

   

3. When the project files have been imported, click the Debug Console tab to see the program output.

   

{% data reusables.codespaces.committing-link-to-procedure %}

You should now be able to add a custom dev container configuration to your own Java project.

{% data reusables.codespaces.next-steps-adding-devcontainer %}