AndroidJavaProxy pass empty string after using il2cpp

Hi everyone,

I using AndroidJavaProxy to pass string result from java native WebRequest (Volley) into Unity project, it's all work before i using il2cpp to build Android Studio project.

I found when using Android 5 (including below version) devices, if the length of response text from WebRequest was too long, then it become empty string in Unity side. I already added preserveAttribute to my class and method, but the issue still there.

I print the response text in java side, it was all correct, but when i print the text from callback method in unity, it was empty.

Other Android Version (5 above) not happen this issue, change to mono scripting backend also work fine.

Unity version : 2017.4.1f1
Volley version : 1.1.0
Scripting Backend : il2cpp

Did someone saw this issue before? I can't found any discuss on internet.

Thanks for your help!

 

Hi @JoshPeterson, We had the similar issue with il2cpp and we finally figure it out that:

The Unity will receive empty string when passing the string that contains emoji chars.

We have a java class declared:

Code (JavaScript):

1. public interface NativeRequestListener {
2.  
3.     void onRequestCompleted (int statusCode, String errorMsg, String jsonResponse);
4. }

and in Unity

Code (CSharp):

1. public class FDNativeRequestListenerCallBack : AndroidJavaProxy {
2.  
3.         FDNativeRequest m_Request;
4.  
5.         public FDNativeRequestListenerCallBack (FDNativeRequest request) : base ("com.fourdesire.unity.FDNativeRequestListener") {
6.  
7.             m_Request = request;
8.         }
9.  
10.         public void onRequestCompleted (int statusCode, string errorMsg, string jsonResponse) {
11.  
12.             We'll get empty string if jsonResponse contains emoji chars ******** with Android 5 and below
13.        }
14.    }
15.  

We pass the m_Listener:FDNativeRequestListenerCallBack to java as follows:

Code (CSharp):

1. AndroidJavaClass unityHelper = new AndroidJavaClass ("com.fourdesire.unity.FDNativeRequestHelper");
2.             unityHelper.CallStatic ("Get", uri.AbsoluteUri, JsonConvert.SerializeObject (m_Parameters), m_Listener);

So, in order to fix the issue temporarily, we pass bytearray instead of string as follows:

Code (JavaScript):

1. public interface FDNativeRequestListener {
2.  
3.     void onRequestCompletedBytes (int statusCode, String errorMsg, FDNativeRequest.ByteArrayWrapper jsonResponse);
4. }
5.  
6. public class FDNativeRequest {
7.  
8.     public class ByteArrayWrapper {
9.  
10.         public byte[] Buffer;
11.  
12.         public ByteArrayWrapper (byte[] buffer) {
13.  
14.             Buffer=buffer;
15.         }
16.     }
17.  
18.      ......
19. }

in Unity

Code (CSharp):

1. public class FDNativeRequestListenerCallBack : AndroidJavaProxy {
2.  
3.         public FDNativeRequestListenerCallBack () : base ("com.fourdesire.unity.FDNativeRequestListener") {
4.  
5.         }
6.  
7.         public void onRequestCompletedBytes (int statusCode, string errorMsg, AndroidJavaObject data) {
8.  
9.             AndroidJavaObject bufferObject = data.Get<AndroidJavaObject> ("Buffer");
10.             byte [] buffer = AndroidJNIHelper.ConvertFromJNIArray<byte []> (bufferObject.GetRawObject ());
11.  
12.             var jsonString = System.Text.Encoding.UTF8.GetString (buffer);
13.         }
14.     }

Now the problem resolved for most of android 5 users, however we got another issue reported from Fabric (but not that much).

Caused by java.lang.AbstractMethodError
abstract method "void com.fourdesire.unity.FDNativeRequestListener.onRequestCompletedBytes(int, java.lang.String, com.fourdesire.unity.FDNativeRequest$ByteArrayWrapper)"

we are using Unity 2017.4.1f1