Start android service from Unity3D code

Below are two ways to send Activity instance/reference to Java plugin that doesn’t use the onCreate function or extend from UnityPlayerActivity.

Method 1: Send Activity reference once then store it in a static variable in Java for re-usual:

Java:

public final class StatusCheckStarter {

    static Activity myActivity;

    // Called From C# to get the Activity Instance
    public static void receiveActivityInstance(Activity tempActivity) {
        myActivity = tempActivity;
    }

    public static void StartCheckerService() {
        myActivity.startService(new Intent(myActivity, CheckService.class));
    }
}

C#:

AndroidJavaClass unityClass;
AndroidJavaObject unityActivity;
AndroidJavaClass customClass;

void Start()
{
    //Replace with your full package name
    sendActivityReference("com.example.StatusCheckStarter");

   //Now, start service
   startService();
}

void sendActivityReference(string packageName)
{
    unityClass = new AndroidJavaClass("com.unity3d.player.UnityPlayer");
    unityActivity = unityClass.GetStatic<AndroidJavaObject>("currentActivity");
    customClass = new AndroidJavaClass(packageName);
    customClass.CallStatic("receiveActivityInstance", unityActivity);
}

void startService()
{
    customClass.CallStatic("StartCheckerService");
}

Method 2: Send Activity reference in each function call.

Java:

public final class StatusCheckStarter {

    public static void StartCheckerService(Activity tempActivity) {
        tempActivity.startService(new Intent(tempActivity, CheckService.class));
    }
}

C#:

void Start()
{
    //Replace with your full package name
    startService("com.example.StatusCheckStarter");
}

void startService(string packageName)
{
    AndroidJavaClass unityClass = new AndroidJavaClass("com.unity3d.player.UnityPlayer");
    AndroidJavaObject unityActivity = unityClass.GetStatic<AndroidJavaObject>("currentActivity");
    AndroidJavaClass customClass = new AndroidJavaClass(packageName);
    customClass.CallStatic("StartCheckerService", unityActivity);
}

Note: You must replace com.example.StatusCheckStarter with the full package of your StatusCheckStarter class.