configure_java.md - mozsearch

# Configure Java for Android

If you are building Android via the command line (which includes our recommended pre-push hooks), you will need to configure Java. If not, you can just use Android Studio and do not need to read further.

Notes:

- this guide is written using macOS and will need to be updated to additionally support Linux and Windows.

- if you find a better way to do configure Java, let us know!

## Background

At the time of writing, Android development seems to work best when using Java 8. By default `brew` and other package managers will install more recent versions that may throw errors during development.

Caveat: Robolectric warns that Java 9 is needed for certain functionality. This seems inconsistent with the rest of the Android ecosystem, however.

## Methods

### Method #1: configure Java 8 from Android Studio

Do the following:

* Download and install Android Studio

* Add the following line to your `~/.zshrc` or equivalent shell startup file: `export JAVA_HOME="/Applications/Android Studio.app/Contents/jbr/Contents/Home"`

  * Update the path if you installed Android Studio to a non-standard location

That's it! To verify correctness, open a new shell, navigate to a directory with Android source code, and type `./gradlew tasks`.

This works because macOS comes with a `/usr/bin/java` stub which will defer the location of the JDK to the value in the `JAVA_HOME` environment variable.

### Method #2: install Java 11 from Homebrew

You can install Java from [Homebrew]([url](https://brew.sh/)) using the command below.

```bash

brew install java11

```

### Method #3: install from website

TODO

## Troubleshooting

### Get Java version

To see what version of Java you have installed, run:

```sh

java -version

```

If you have Java 8 configured, you'll see output like:

```

openjdk version "1.8.0_242-release"

OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6222593)

OpenJDK 64-Bit Server VM (build 25.242-b3-6222593, mixed mode)

```

### Error running pre-push hooks

If you encounter this error, particularly when running our recommended pre-push hooks:

```

Could not initialize class org.codehaus.groovy.runtime.InvokerHelper

```

You may be on Java 14: consider installing Java 8 (see above). If preferred, other users have found installing any version of Java, 13 or lower, appears to resolve the issue:

Steps to downgrade Java Version on Mac with Brew:

1. Install Homebrew (https://brew.sh/)

2. run ```brew update```

3. To uninstall your current java version, run ```sudo rm -fr

   /Library/Java/JavaVirtualMachines/<jdk-version>```

4. run ```brew tap homebrew/cask-versions```

5. run ```brew search java```

6. If you see java11, then run ```brew install java11```

7. Verify java-version by running ```java -version```

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