import extranl dll in java

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i tried to import dll using system.load().but it showing an exception of java.lang.UnsatisfiedLinkError: led_data_send.SendColorTp(IIIILjava/lang/String;IIII)I.
i kept dll in d drive.so i specified the path of dll to d://LEDBAR.dll
i am calling a function SendColorTp in dll.

code as shown below

Java

private native int SendColorTp(int Port, int Addr, int Mode, int Delay, String Context, int FontSize, int FontColor, int SignWidth, int SignHeight);

static{
    System.load("D:\\LEDBAR.dll");
}

Posted 22-Jul-13 23:53pm

harishhn

Updated 23-Jul-13 1:10am

pasztorpisti

v3

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Shubhashish_Mandal 23-Jul-13 8:02am

I guess that the dll is loaded successfully otherwise you will get the following error
"java.lang.UnsatisfiedLinkError: Unable to load library ". So check the method you called is present in the dll or not

pasztorpisti 23-Jul-13 15:37pm

You are probably right. Using the javah tool would help to avoid bad implementation signatures.

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pasztorpisti · Answer 1 · 2013-07-23T01:16:00

First compile your java source into a class file (inside your ide or with javac). Then run the javah program on the class file. This javah program will generate the function declarations into a C/C++ header file. Use this header to implement/export the functions in your DLL.
Example:

_package/X.java:

Java

package _package;

public class X
{
    public native int func(float f, boolean b);

    public static void main(String[] args)
    {
        System.out.println("Hello World!");
    }
}

We run the following commands outside the _package directory:

javac _package/*.java
javah _package.X

After running these commands you will find a _package_X.h file in the current dir.