I have a huge C++ library for image processing. I would like to use this DLL library in an Android project. How can I call methods in the C++ DLL library in Android?
Maybe you can try JavaCPP. JavaCPP will help you auto generate appropriate code for JNI, and passes it to the C++ compiler to build a native library.
For more details and examples, please seeļ¼ https://code.google.com/p/javacpp/
via JNI Java Native Interface.
using this keyword will let you find a tutorial:
http://developer.android.com/training/articles/perf-jni.html
You need the Java Native Interface (JNI)
Oracle has a great set of tutorials on it (google for them).
Also, since you tagged your question Android, I'm presuming that's the platform you need JNI on.
You'll have to look into the Native Development Kit, more info on that here: http://developer.android.com/tools/sdk/ndk/index.html
Related
I was wondering if writing apps in C++ in Android Studio is possible. I have some knowledge in creating apps in Java but I am more comfortable with C++, and is this a complicated process?
You can use Qt and create Android apps with C++ (http://doc.qt.io/qt-5/androidgs.html).
To setup Android Studio with Qt https://wiki.qt.io/Android
You can add C and C++ code to your Android project by placing the code into a cpp directory in your project module.
When you build your project, this code is compiled into a native library that Gradle can package with your APK.
Your Java or Kotlin code can then call functions in your native library through the Java Native Interface (JNI). If you want to learn more about using the JNI framework, read JNI tips for Android.
You can also use JNI to run c++ code (as a matter of fact c++ shared library or so) from Java.
Here you can find a usefull article + sample for how to do it.
I have function implemented in C++ with several parameters and outputs. I want to use this function in my Android Studio Java code as a black box to pass necessary arguments and get results. The problem is that C++ function uses several libraries such as OpenCV together with other C++ implemented functions. I read about NDK and JNI and tried to do simple "Hello from C++" function call and it works. However, I do not understand how to install all libraries to C++ and how to put all necessary C++ codes.
You can find nice tutorial about JNI here.
I am currently working on an android project that requires me to make use of functions included in a shared library (.so). I also only have header (.h) files for the library provided to me.
Is it possible to work with just these two files? Or do I need to create my own implemenations via c++ codes?
I am using Android Studio intend to use CMake.
Regards,
Philip
Most Android apps are written in Java. Google has released the Native Developer Kit (NDK) in order to allow developers to write libraries in C++. However, these libraries are usually very low level and called from the Java code which defines the UI and higher-level app logic. Most likely you will need to write a wrapper for the library so that you can call it from Java code. Looks like this blog is a good place to start.
I have used a native C++ DLL in Xamarin.Android using [DLLImport] but I am getting exception System.DllNotFoundException. I have used same way as I do in C#. Plz provide me some simple code which explains all steps so that I can know if something extra has to be done for Xamarin.Android.
If you importe your library and you linked it in your project
you should use.
[DllImport ("__Internal")]
Instead of using a name of your library.
[DllImport ("LibraryName")]
I successfully installed and builded the pjsip library and pjsua for android, I ran pjsua on my device and it worked, however I'm still lost on how to use the methods of this library.
I already took a look on the CSipSimple app and I noticed that the jni folders of these 2 projects are very different.
Do I have to convert each .c file of this library in .java files with SWIG?
If anyone has an example about how to implement it in a very simple way (a SIP register procedure for instance) it would be helpful.
It depends on how you would like to use the library.
The highest level API for pjsip is pjsua2 API, and there is already a java SWIG library build for you in the source code. You can just look at these examples.
http://www.pjsip.org/docs/book-latest/html/intro_pjsua2.html#building-python-and-java-swig-modules
However, if you don't need the sip signaling part, but just the media codecs and transportation part. You might have to design a JNI interfaces by yourself.
You write the programs in C/C++ and link the libpjsua.so in the Android.mk file.
for pjsua api C programming example:
http://www.pjsip.org/docs/latest/pjsip/docs/html/group__PJSUA__LIB__BASE.htm
for pjmedia example: see the testing codes under pjmedia/src/test