jni / java.lang.UnsatisfiedLinkError occurred at System.loadLibrary

[John Pyun]

Hi~
Sorry for my English.

I created files like below.

TestJNI.java

import java.lang.reflect.Field; 

class TestJNI 
{ 
    static 
    { 
        System.loadLibrary("TestJNI"); 
    } 

    public static void main(String args[]) 
    { 

        TestJNI testjni = new TestJNI(); 
        testjni.prn(100); 
    } 

    public native void prn(int a); 
} 

TestJNI.c
#include <stdio.h> #include "TestJNI.h" JNIEXPORT void JNICALL Java_TestJNI_prn (JNIEnv *env, jobject obj, jint param1) { printf("____%d\n", param1); }

build.sh
!/bin/bash LD_LIBRARY_PATH=`pwd`:$LD_LIBRARY_PATH export LD_LIBRARY_PATH javac TestJNI.java javah TestJNI g++ -shared -fPIC -I/<<JDK directory>>/include -I/<<JDK directory>>/include/linux -o TestJNI.so TestJNI.c java -Djava.library.path=. TestJNI

then executed "build.sh". but error occurred.

iknow82@notebook :~/tmp/test$ ./build.sh
Exception in thread "main" java.lang.UnsatisfiedLinkError: no TestJNI in java.library.path
at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1857)
at java.lang.Runtime.loadLibrary0(Runtime.java:870)
at java.lang.System.loadLibrary(System.java:1119)
at TestJNI.<clinit>(TestJNI.java:6)

Is there anyone who tell the tips to fix the error?

[Mike. J. Thompson]

Well the error itself tells you the problem. You need to set java.library.path to point to the directory that contains the shared objects/dlls.

You can do this using the -D option to the java executable.

java -Djava.library.path="path/to/the/directory" ...

[Campbell Ritchie]

Welcome to the Ranch

JNI is far too difficult for us who are just “beginning”(‍), so I shall move this discussion.

[John Pyun]

I've resolved the issue by simple way. just changed .so library name 'TestJNI.so' to 'libTestJNI.so'.
It's Ubuntu 14.04 x64.
thanks for your attention.

[Campbell Ritchie]

That change sounds dangerous. Did you copy the original .so?

[John Pyun]

I'd heard several solutions to 'java.lang.UnsatisfiedLinkError' exception.
one is to set LD_LIBRARY_PATH and another is to run app by 'java -Djava.library.path=<<library path>> <<class name>>'.
In my case. although accepted two solutions. couldn't read TestJNI.so file. but after was renamed 'libTestJNI.so'. It works. of course, it was launched 'java -Djava.library.path=<<library path>> <<class name>>'.
I don't know why %modulename%.so format could be read by java.

ps. you know... my english is not good. so if there is my misunderstanding, forgive...

[Campbell Ritchie]

What if another program needs the TestJNI.so link?