Create an Android Library plug-in

You can create an Android Library plug-in in Unity. Once created, you can directly use it within your Unity project or develop it further in Android Studio.

To create an Android Library plug-in, follow these steps:

1. In the Project window, navigate to the folder where you want to create the Android Library plug-in.
2. Right-click the folder and select Create > Plugins > Android Library.

Unity creates a new Android Library plug-in that includes build.gradle, AndroidManifest.xml, and source files.

Alternatively, you can create the Android Library plug-in manually by following these steps:

1. In your Unity project, create a MyFeature.androidlib folder. This folder will represent a Gradle module.

2. (Optional) Unity will create a build.gradle for your .androidlib automatically on build, but if you want to override it, create a file named build.gradle inside the MyFeature.androidlib folder and add the following code:

   apply plugin: 'com.android.library'
   
   dependencies {
       implementation fileTree(dir: 'libs', include: ['*.jar'])
   }
   
   android {
       namespace "com.company.myfeature"
       compileSdk getProperty("unity.compileSdkVersion") as int
       buildToolsVersion getProperty("unity.buildToolsVersion")
   
       compileOptions {
           sourceCompatibility JavaVersion.valueOf(getProperty("unity.javaCompatibilityVersion"))
           targetCompatibility JavaVersion.valueOf(getProperty("unity.javaCompatibilityVersion"))
       }
   
       defaultConfig {
           minSdk getProperty("unity.minSdkVersion") as int
           targetSdk getProperty("unity.targetSdkVersion") as int
           ndk {
               abiFilters.addAll(getProperty("unity.abiFilters").tokenize(','))
               debugSymbolLevel getProperty("unity.debugSymbolLevel")
           }
           consumerProguardFiles 'proguard-rules.pro'
       }
   
       buildTypes {
           release {
               minifyEnabled false
               proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
           }
       }
   }
   

3. Create the following folder structure inside the MyFeature.androidlib folder:
   • src/main
   • src/main/java/com/company/feature (or adjust the package path to match your desired package name)

4. Create an AndroidManifest.xml file inside the src/main folder and add the following code:

   <?xml version="1.0" encoding="utf-8"?>
   <manifest xmlns:android="http://schemas.android.com/apk/res/android"/>
   

5. Create a Java or Kotlin file (for example, Controller.java) inside the src/main/java/com/company/feature/ folder and add the following code:

   package com.company.feature;
   
   public class Controller
   {
       public static String getFoo()
       {
           return "This is my feature";
       }
   }
   

The Android Library plug-in is now created.

Use Android Library plug-ins

To use the Android Library plug-in within your Unity project, use the following code:

using UnityEngine;

public class FeatureUser : MonoBehaviour
{
    readonly string ControllerName = "com.company.feature.Controller";
    AndroidJavaClass m_Class;
    void Start()
    {
        m_Class = new AndroidJavaClass(ControllerName);
    }

    private void OnGUI()
    {
        GUILayout.Space(100);
        GUI.skin.label.fontSize = 30;

        if (m_Class != null)
        {
            GUILayout.Label($"{ControllerName}.getFoo() returns " + m_Class.CallStatic<string>("getFoo"));
        }
        else
        {
            GUILayout.Label($"{ControllerName} was not found?");
        }
    }
}

Develop Android Library plug-ins

As the source files of the Android Library plug-ins aren’t visible in the Unity C# project, modifying or further developing the plug-in requires additional steps as follows:

1. Open the Build Profiles (menu: File > Build Profiles) window.
2. From the list of platforms in the Platforms panel, select Android.
3. Under Platform Settings, enable Export Project and Symlink Sources.
4. Select Export.
5. Select the destination folder and click Select Folder to start the export process.
6. After Unity exports the Gradle project, import the Gradle project into Android Studio.

You can develop your Android Library plug-in from Android Studio. As the Unity project directly references the plug-in, any modifications to the Android Library plug-in automatically reflect in the Unity project.

Additional resources

• Export an Android project