Java, C JNI - java.lang.UnsatisfiedLinkError : No .dylib in java.library.path-CodePudding

I was trying to link java and c code using java JNI but when I ran the java file using dylib path, getting an error that no file was available. However, my lib file is available in the current working directory.

Also, I tried moving same dylib to /Library/Java/Extensions but still the same error.

Java File: JNIJava.java

public class JNIJava {
    static {
        System.loadLibrary("JNI_CPP");
    }
    public native void printString(String name);
   
    public static void main(final String[] args) {
        JNIJava jniJava = new JNIJava();
        jniJava.printString("Invoked C   'printString' from Java");
    }
}

Header file : JNIJava.h

/* DO NOT EDIT THIS FILE - it is machine generated */
#include "/Library/Java/JavaVirtualMachines/jdk1.8.0_261.jdk/Contents/Home/include/jni.h"
/* Header for class JNIJava */

#ifndef _Included_JNIJava
#define _Included_JNIJava
#ifdef __cplusplus
extern "C" {
#endif
/*
 * Class:     JNIJava
 * Method:    printString
 * Signature: (Ljava/lang/String;)V
 */
JNIEXPORT void JNICALL Java_JNIJava_printString
  (JNIEnv *, jobject, jstring);

#ifdef __cplusplus
}
#endif
#endif

C file : JNIJava.cpp

#include <iostream>
#include "JNIJava.h"

using namespace std;

JNIEXPORT void JNICALL Java_JNIJava_printString(JNIEnv *env, jobject jthis, jstring string) {
    const char *stringInC = env->GetStringUTFChars(string, NULL);
    if (NULL == stringInC)
        return;
    cout << stringInC << endl;
    env->ReleaseStringUTFChars(string, stringInC);
}

Used the below commands to link and run the code :

javac JNIJava.java -h .

g   -dynamiclib -O3 \
    -I/Library/Java/JavaVirtualMachines/jdk1.8.0_261.jdk/Contents/Home/include \
    -I/Library/Java/JavaVirtualMachines/jdk1.8.0_261.jdk/Contents/Home/include \
    JNIJava.cpp -o JNI_CPP.dylib

java -cp . -Djava.library.path=$(pwd) JNIJava

When I Do ls :

JNIJava.class           JNIJava.cpp             JNIJava.h               JNIJava.java            JNI_CPP.dylib

Error :

Exception in thread "main" java.lang.UnsatisfiedLinkError: no JNI_CPP in java.library.path: /Users/tkapadn/Documents/Documents_Data/Lens-Eclipse-Workspace/Java_JNI/CPP
        at java.base/java.lang.ClassLoader.loadLibrary(ClassLoader.java:2447)
        at java.base/java.lang.Runtime.loadLibrary0(Runtime.java:809)
        at java.base/java.lang.System.loadLibrary(System.java:1893)
        at JNIJava.<clinit>(JNIJava.java:3)

Here is the screenshot of the error :

enter image description here

Note - I tried linking c with java using JNI and I was successfully able to run the java file.

Java Version - jdk1.8.0_261, System - macOS Big Sur (11.6.1)

Please provide your suggestions.

CodePudding user response：

instead of using 'System.loadLibrary("")' use 'System.load("lib path")' and check if the library is working.then you can move it to the java library path.

for example : (tested and working)

try { 

String libPath = System.getProperty("user.dir")   System.getProperty("file.separator")   System.mapLibraryName("JNI_CPP"); 
System.load(libPath); 

} catch (Exception e) {
 System.out.println(e.toString());
}

CodePudding user response：

Your call to System.loadLibrary must omit the lib part of the filename:

        System.loadLibrary("JNI_CPP");

Your cpp file should match the headerfile, so remove the com_example_jni_ part of your function name.