Sending data to Unity

Question

I am developing a project which includes Android app and Unity app. The main app is Android which at some point opens the Unity app. I exported the Unity app as Android plugin and integrated it in the Android studio as AAR module. When I open Unity app from Android I have to send a variable (integer) and retrieve it in Unity. Depending on this integer then I activate different objects. My question is how to send this integer in Android and then retrieve it in Unity? I read and tried a lot, used "UnityPlayer.UnitySendMessage" in Android and "AndroidJavaObject" in Unity but I didn't manage to achieve what I want.

Package name of Android app is "android.unityembed" and of Unity is "com.borut.multiple".

Java code:

package android.unityembed;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

import com.unity3d.player.UnityPlayer;
import com.borut.multiple.UnityPlayerActivity;

public class Start extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.start);

    Button button = (Button) findViewById(R.id.button);
    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Intent intent = new Intent(getApplicationContext(), UnityPlayerActivity.class);
            startActivity(intent);
        }
    });
}

public static int OnSceneLoadComplete(){
    return 1;
}

}

Unity code:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.VR;

public class NormalStart : MonoBehaviour {
public GameObject space1;
public GameObject space2;

// Use this for initialization
void Start () {
    StartCoroutine (LoadDeviceInit ("", false));

    // x is the variable you get from Java
    AndroidJavaClass jc = new AndroidJavaClass ("android.unityembed.Start");
    int x = jc.CallStatic<int> ("OnSceneLoadComplete");
}

// Update is called once per frame
void Update () {
}

public void active1() {
    space1.SetActive (true);
}

public void active2() {
    space2.SetActive (true);
}

IEnumerator LoadDeviceInit(string newDevice, bool enable)
{
    Debug.Log ("LoadDevice: " + newDevice + " enabled: " + enable);
    VRSettings.LoadDeviceByName(newDevice);
    yield return null;
    VRSettings.enabled = enable;
    yield return null;
    Camera.main.ResetAspect();

}

//Called from Java to receive message
public void JavaMessageReceiver(string message)
{
    Debug.Log("Received Message form Java: "+message);
}

}

EDIT: I solved the problem, updated code above does what I wanted.

I have another issue. My Unity app uses Google VR SDK and it's implemented also for Cardboard. When I build Unity app normally (I get .apk file) the Cardboard loads like it should (split screen). But when I export this app as a module in Android Studio, when I run UnityPlayerActivity the Cardboard view doesn't load, the scene is loaded like a normal Unity 3D scene.

Here are two screenshots of Android Studio Logcat: Logcat 1 Logcat 2

Here is also a screenshot of my Player Settings in Unity. Sometimes I want to load the Cardboard, sometimes not (depending on user's choice). Unity Player Settings

How can I solve this problem?