Using Java or Kotlin source files as plug-ins

Unity supports plug-insA 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 for Android written in Java or Kotlin. This functionality allows you to add .java or .kt files into your Unity Project and they are compiled when you build an Android player. Previously you had to precompile these files as an android library.

Gradle is the only build system that supports this feature so use 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 as your build system.

To compile the source files as a plug-in:

1. Open the Unity Editor.
2. Select the Project to add the plug-in to.
3. In the Projects window, select the Assets folder and create a folder for your plug-in.
4. Drag and drop your source files into the folder.
5. Select each of the files.
6. In the inspectorA Unity window that displays information about the currently selected GameObject, Asset or Project Settings, alowing you to inspect and edit the values. More info
   See in Glossary window, under Select platforms for plugin, verify that only Android is selected.
7. Build your Project.

Note: You can place your source files in any folder in your Project except in special use locations such as subfolders under Assets/Plugins/Android. If you place files in these locations, the Unity Editor will not display the plug-in inspector. For additional information, see AAR plug-ins and Android Libraries.

Use the AndroidJavaObject class to call methods in your plug-in. For additional information see, the “Using your Java plug-in from C# scriptsA piece of code that allows you to create your own Components, trigger game events, modify Component properties over time and respond to user input in any way you like. More info
See in Glossary with helper classes” section in JAR plug-ins.

Symlink Sources

To enable direct referencing of the Java and Kotlin files in the exported gradle project and eliminte the need to manually copy the edited Java and Kotlin files from the exported gradle project to the Unity Project, enable Symlink Sources in the Build Settings window.

• 2018–12–08 Added Symlink Sources option.
• 2018–11–29  Page amended with editorial review
• 2018–09–07 Page published with editorial review
• Added plug-in support in 2018.2