Create an Android Library plug-in

You can create an Android Library plug-inA set of code created outside of Unity that creates functionality in Unity. There are two kinds of plug-ins you can use in Unity: Managed plug-ins (managed .NET assemblies created with tools like Visual Studio) and Native plug-ins (platform-specific native code libraries). More info
See in Glossary 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 your Unity project, create MyFeature.androidlib folder. This folder will represent a GradleAn Android build system that automates several build processes. This automation means that many common build errors are less likely to occur. More info
   See in Glossary module.

2. 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.javaCompatabilityVersion"))
           targetCompatibility JavaVersion.valueOf(getProperty("unity.javaCompatabilityVersion"))
       }
   
       defaultConfig {
           minSdk getProperty("unity.minSdkVersion") as int
           targetSdk getProperty("unity.targetSdkVersion") as int
           ndk {
               abiFilters.addAll(getProperty("unity.abiFilters").tokenize(','))
               debugSymbolLevel getProperty("unity.debugSymbolLevel")
           }
           versionCode getProperty("unity.versionCode") as int
           versionName getProperty("unity.versionName")
       }
   
       buildTypes {
           release {
               minifyEnabled false
               proguardFiles getDefaultProguardFile    ('proguard-android-optimize.txt'), 'proguard-rules. pro'
           }
       }
   }
   

3. Create the following folders inside the MyFeature.androidlib folder:
   • MyFeature.androidlib/src
   • MyFeature.androidlib/src/main

4. Create an AndroidManifest.xml file inside the MyFeature.androidlib/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 file named Controller.java inside the MyFeature.androidlib/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