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Jan 1, 2011 · JNA provides Java programs easy access to native shared libraries (DLLs on Windows) without writing anything but Java code—no JNI or native code is required. This functionality is comparable to Windows' Platform/Invoke and Python's ctypes.
- Introduction
- How It Works
- Hello World JNI
- Using Advanced JNI Features
- Disadvantages of Using JNI
- Conclusion
As we know, one of the main strengths of Java is its portability – meaning that once we write and compile code, the result of this process is platform-independent bytecode. Simply put, this can run on any machine or device capable of running a Java Virtual Machine, and it will work as seamlessly as we could expect. However, sometimes we do actually...
2.1. Native Methods: the JVM Meets Compiled Code
Java provides the nativekeyword that’s used to indicate that the method implementation will be provided by a native code. Normally, when making a native executable program, we can choose to use static or shared libs: 1. Static libs – all library binaries will be included as part of our executable during the linking process. Thus, we won’t need the libs anymore, but it’ll increase the size of our executable file. 2. Shared libs – the final executable only has references to the libs, not the co...
2.2. Components Needed
Here’s a brief description of the key components that we need to take into account. We’ll explain them further later in this article 1. Java Code – our classes. They will include at least one nativemethod. 2. Native Code – the actual logic of our native methods, usually coded in C or C++. 3. JNI header file – this header file for C/C++ (include/jni.hinto the JDK directory) includes all definitions of JNI elements that we may use into our native programs. 4. C/C++ Compiler – we can choose betw...
2.3. JNI Elements in Code
Java elements: 1. “native” keyword – as we’ve already covered, any method marked as native must be implemented in a native, shared lib. 2. System.loadLibrary(String libname)– a static method that loads a shared library from the file system into memory and makes its exported functions available for our Java code. C/C++ elements (many of them defined within jni.h) 1. JNIEXPORT- marks the function into the shared lib as exportable so it will be included in the function table, and thus JNI can fi...
Next, let’s look at how JNI works in practice. In this tutorial, we’ll use C++ as the native language and G++ as compiler and linker. We can use any other compiler of our preference, but here’s how to install G++ on Ubuntu, Windows, and MacOS: 1. Ubuntu Linux – run command “sudo apt-get install build-essential”in a terminal 2. Windows – Install Min...
Saying hello is nice but not very useful. Usually, we would like to exchange data between Java and C++ code and manage this data in our program.
JNI bridging does have its pitfalls. The main downside being the dependency on the underlying platform; we essentially lose the “write once, run anywhere”feature of Java. This means that we’ll have to build a new lib for each new combination of platform and architecture we want to support. Imagine the impact that this could have on the build proces...
Compiling the code for a specific platform (usually) makes it faster than running bytecode. This makes it useful when we need to speed up a demanding process. Also, when we don’t have other alternatives such as when we need to use a library that manages a device. However, this comes at a price as we’ll have to maintain additional code for each diff...
Sep 29, 2023 · Java JNA provides a convenient way to access hardware devices from Java programs without writing complex native code in C/C++. By using JNA, you can develop platform-independent code to interact with hardware devices, simplifying the development process and improving code maintainability.
In this tutorial, we’ll see how to use the Java Native Access library (JNA for short) to access native libraries without writing any JNI (Java Native Interface) code. 2. Why JNA?
Here you can download Visual Studio:https://visualstudio.microsoft.comHere you can download Java JDK 11:https://www.oracle.com/java/technologies/javase-jdk11...
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You can use VS Code to read, write, run, and debug Java source file(s) without creating a project. VS Code for Java supports two modes, lightweight and standard. Lightweight mode is ideal for scenarios that only deal with source file(s).
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First navigate(using cd) to the folder where your java and C code is presentTo compile java code:javac -h . filename.javaTo compile C code:gcc -c -I"%JAVA_HO...
