# OpenCV Java SDK not building in React Native app as Native Module: android packages and symbols not existing
**URL:** https://forum.opencv.org/t/opencv-java-sdk-not-building-in-react-native-app-as-native-module-android-packages-and-symbols-not-existing/14985
**Category:** Android/Java
**Tags:** java, android, build
**Created:** [October 25, 2023, 11:56am UTC](https://forum.opencv.org/t/opencv-java-sdk-not-building-in-react-native-app-as-native-module-android-packages-and-symbols-not-existing/14985 "2023-10-25T11:56:24Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@Wessel](https://forum.opencv.org/u/Wessel)
#### Post date: [October 25, 2023, 11:56am UTC](https://forum.opencv.org/t/opencv-java-sdk-not-building-in-react-native-app-as-native-module-android-packages-and-symbols-not-existing/14985/1 "2023-10-25T11:56:25Z")
### System Information
OpenCV version: 4.8.0
OS: Windows 11
Java SDK: 11.0.20
Gradle version: 6.9.4
### Detailed description
I have a React Native app where I want to add the OpenCV Java SDK as a Native Module. I have tried various tutorials to make this work, and now I have done all the steps described [in this StackOverflow answer](https://stackoverflow.com/a/64500728/14567247) . However, when I try to run the project, I get a `> Task :opencv:compileDebugJavaWithJavac FAILED` with the logs below showing that basic packages as andorid.content and android.util do not exist.
I could build just fine prior to adding openCV, and these errors only show up for this openCV task. How do I fix this?
> **Android Studio Build Output log**
>
> ```auto
> C:\PATH_TO_MY_APP\android\opencv\java\src\org\opencv\android\AsyncServiceHelper.java:9: error: package android.content does not exist
> import android.content.ComponentName;
> ^
> C:\PATH_TO_MY_APP\android\opencv\java\src\org\opencv\android\AsyncServiceHelper.java:10: error: package android.content does not exist
> import android.content.Context;
> ^
> C:\PATH_TO_MY_APP\android\opencv\java\src\org\opencv\android\AsyncServiceHelper.java:11: error: package android.content does not exist
> import android.content.Intent;
> ^
> C:\PATH_TO_MY_APP\android\opencv\java\src\org\opencv\android\AsyncServiceHelper.java:12: error: package android.content does not exist
> import android.content.ServiceConnection;
> ^
> C:\PATH_TO_MY_APP\android\opencv\java\src\org\opencv\android\AsyncServiceHelper.java:13: error: package android.net does not exist
> import android.net.Uri;
> ^
> C:\PATH_TO_MY_APP\android\opencv\java\src\org\opencv\android\AsyncServiceHelper.java:14: error: package android.os does not exist
> import android.os.IBinder;
> ^
> C:\PATH_TO_MY_APP\android\opencv\java\src\org\opencv\android\AsyncServiceHelper.java:15: error: package android.os does not exist
> import android.os.RemoteException;
> ^
> C:\PATH_TO_MY_APP\android\opencv\java\src\org\opencv\android\AsyncServiceHelper.java:16: error: package android.util does not exist
> import android.util.Log;
> ^
> C:\PATH_TO_MY_APP\android\opencv\java\src\org\opencv\android\AsyncServiceHelper.java:20: error: cannot find symbol
> public static boolean initOpenCV(String Version, final Context AppContext,
> ^
> symbol: class Context
> location: class AsyncServiceHelper
> C:\PATH_TO_MY_APP\android\opencv\java\src\org\opencv\android\AsyncServiceHelper.java:38: error: cannot find symbol
> protected AsyncServiceHelper(String Version, Context AppContext, LoaderCallbackInterface Callback)
> ^
> symbol: class Context
> location: class AsyncServiceHelper
> C:\PATH_TO_MY_APP\android\opencv\java\src\org\opencv\android\AsyncServiceHelper.java:50: error: cannot find symbol
> protected Context mAppContext;
> ^
> symbol: class Context
> location: class AsyncServiceHelper
> C:\PATH_TO_MY_APP\android\opencv\java\src\org\opencv\android\AsyncServiceHelper.java:54: error: cannot find symbol
> protected static boolean InstallServiceQuiet(Context context)
> ^
> symbol: class Context
> location: class AsyncServiceHelper
> C:\PATH_TO_MY_APP\android\opencv\java\src\org\opencv\android\AsyncServiceHelper.java:71: error: cannot find symbol
> protected static void InstallService(final Context AppContext, final LoaderCallbackInterface Callback)
> ^
> symbol: class Context
> location: class AsyncServiceHelper
> C:\PATH_TO_MY_APP\android\opencv\java\src\org\opencv\android\AsyncServiceHelper.java:156: error: cannot find symbol
> protected ServiceConnection mServiceConnection = new ServiceConnection()
> ^
> symbol: class ServiceConnection
> location: class AsyncServiceHelper
>
> ```
### Steps to reproduce
Follow the steps [in this StackOverflow answer](https://stackoverflow.com/a/64500728/14567247) and try to run in debug mode in Android Studio
---
### Author:  [@rajmb](https://forum.opencv.org/u/rajmb)
#### Post date: [November 26, 2023, 4:42am UTC](https://forum.opencv.org/t/opencv-java-sdk-not-building-in-react-native-app-as-native-module-android-packages-and-symbols-not-existing/14985/2 "2023-11-26T04:42:45Z")
I have not tried the steps above & do not have experience with react-native but I see from the post that you are using android studio to set up the java side of the project. Can you check the steps mentioned in this post: [An exercise in frustration](https://forum.opencv.org/t/an-exercise-in-frustration/12964) ? This worked smoothly for me.