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Questions tagged [jnienv]

The env pointer is a structure that contains the interface to the JVM. It includes all of the functions necessary to interact with the JVM and to work with Java objects.

195 questions
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Why does the JNI C API use a pointer-to-pointer instead of straight pointers for JNIEnv?

Disclaimer: I have implemented my own object-oriented programming languages, so am familiar with (and have taught) pointers and C. Memory management 101 is not what this question is about. Neither is this about the JNI C++ API that looks similar.…
uliwitness
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Accessing struct via pointer in C and C++

"Simple" question put short: Why exactly does JNIEnv *g_env = NULL; (*g_env)->ExceptionDescribe(g_env); compile in gcc (C) but not in g++ (C++) error: base operand of ‘->’ has non-pointer type ‘JNIEnv’ {aka ‘JNIEnv_’} As I am working mainly with…
Paxi1337
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JNI Linux segmentation fault

My JNI library works flawlessly on Windows, however, on Linux I always get a strange segmentation fault. siginfo: si_signo: 11 (SIGSEGV), si_code: 1 (SEGV_MAPERR), si_addr: 0x0000000000000000 The stack crace from the crash file is this: C …
Lóránt Viktor Gerber
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Android calling Java function from another activity class in C++ JNI code

As the title suggested, How can I call Java function from C++ if the function is from a different java activity class? All of the sample and tutorials calls C++ function and java back and forth but the caller is the class and the JNIEnv and jobject…
user2300947
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NewDirectByteBuffer returning weird values

I have read many SO Q/A but I really can't get this to work. I need to work with a vector in C++ (a library needs it) in a JNI project. So I am calling a C++ method which initializes the vector and returns a pointer to the underlying array. Java is…
lorenzop
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NDK get instance of AssetManager through JNIEnv (Xamarin.Android, C++)

I'm writing a Xamarin Android App which contains a native C++ library. That native library contains a function which should load an image via the assetmanager. C++ #include #include void…
Florian
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How to release the jbyteArray?

My native method has a method with a byte[] return value, So I use "NewByteArray" to alloc the byte[],then use return to return the jbyteArray. Should I release the jbyteArray? And how to release the jbyteArray? Thank you. I am a Java beginner and…
iseki
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android JNI report can't find method

I'm using the following code for wrapping all the native functions package com.user.game; import android.content.res.AssetManager; public class MyGLRenderer { static { System.loadLibrary("Engine"); } public static native void…
quetzalfir
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Returning local reference created by JNI from a native method

JNI reference says that "Local references are valid for the duration of a native method call. They are freed automatically after the native method returns. Source:…
Vladislavs Burakovs
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JNI GetFieldID returning null for inner class

I have public inner class which i want to access in JNI. GetFieldID is returning null while accessing fieldId for inner class Below is code public class classA{ public class classB{ public int b1; } public int a1; public classB…
Sa Ku
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Call Java function with parameter Map from c++ with std::map

How can I call Java function which takes Map as parameter from C++ when I have std::map in c++. I know how to call Java function from c++ when parameters are simple types as int and so on but how to call for…
PaolaJ.
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Qt JNI : Invalid indirect reference 0x61382e48 in decodeIndirectRef

I am trying the Qt project that captures audio data from mic on android. I refereed this article : Android AudioRecord example, and wrote it to Qt code. int recorderSampleRate = 44100; int recorderChannels =…
covernal
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Android JNI Callback to java from C++

I tried to create a callback from jni to java, But when ever execute my code from cpp thread, findClass method return null, But the same class path & method properly executing from jni thread(Native Thread). static JavaVM * s_Jvm; JNIEXPORT jint…
user2851150
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Android Jni : crash in global and local ref variables

I have jni c++ code that calls java objects methods, example : jclass JIOManager = CJavaEnv::getInstance()->env()->FindClass(ioManagerName); ..... some code CJavaEnv::getInstance()->env()->DeleteLocalRef(JIOManager); this works really fine…
Kamilia
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JNIEnv for get ANDROID_ID from native code

I need to get Android unique device ID in my native library. As far as i know, it can be done with Java API and i need to use JNI. I read this, there is similar problem, but different ID is accessed. But this solution needs reference to JNIEnv for…
exbluesbreaker
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