0

I am trying to load a pre-compiled dynamic library ( libabc.so ) which contains extern functions declared in header and cpp files. But I am getting error during compilation.

The header and CPP file are as below :

[ export.h ]

extern "C" {
void multiply(int a, float b);
}

[ export.cpp ]

#include "export.h"
#include <iostream>
using namespace std;
extern "C" {
void multiply (int a, float b) {
cout << "Hello-World\n";
}
}

I compiled them into a shared object : libabc.so and copied it inside the src/main/java/somepackage/* . ( I am using the sample demo given here : https://github.com/bytedeco/sample-projects/blob/master/javacpp-mvn-simple-demo/ )

I am trying to load the library from Java and call the methods as shown below :

package somepackage;

import org.bytedeco.javacpp.;
import org.bytedeco.javacpp.annotation.;

@Platform(library="abc")
public class MultiplyDemo {

static {
    Loader.load();
}

public native void multiply(int a, float b);

public static void main(String[] args) {

MultiplyDemo mul = new MultiplyDemo();
    mul.multiply(123, 100f);
}    
}

I am getting the error :

[INFO] --- javacpp:1.0:build (process-classes) @ javacpp-mvn-simple-demo ---
[INFO] Executing JavaCPP Builder
[INFO] Generating /home/necuser/nitin/bridge/javacpp-mvn-simple-demo/target/classes/somepackage/jniMultiplyDemo.cpp
[WARNING] The class somepackage.MultiplyDemo does not map to any C++ type. Compilation will most likely fail.
[WARNING] The class somepackage.MultiplyDemo does not map to any C++ type. Compilation will most likely fail.
[WARNING] The class somepackage.MultiplyDemo does not map to any C++ type. Compilation will most likely fail.
[WARNING] The class somepackage.MultiplyDemo does not map to any C++ type. Compilation will most likely fail.
[INFO] Compiling /home/necuser/nitin/bridge/javacpp-mvn-simple-demo/target/classes/somepackage/linux-x86_64/libjniMultiplyDemo.so
[INFO] g++ -I/home/necuser/nitin/bridge/javacpp-mvn-simple-demo/src/main/java -I/usr/lib/jvm/java-8-openjdk-amd64/include -I/usr/lib/jvm/java-8-openjdk-amd64/include/linux /home/necuser/nitin/bridge/javacpp-mvn-simple-demo/target/classes/somepackage/jniMultiplyDemo.cpp -Wl,-rpath,$ORIGIN/ -march=x86-64 -m64 -Wall -O3 -fPIC -shared -s -o /home/necuser/nitin/bridge/javacpp-mvn-simple-demo/target/classes/somepackage/linux-x86_64/libjniMultiplyDemo.so
/home/necuser/nitin/bridge/javacpp-mvn-simple-demo/target/classes/somepackage/jniMultiplyDemo.cpp: In function ‘void Java_somepackage_MultiplyDemo_add_1Conv(JNIEnv*, jobject, jint, jfloat)’:
/home/necuser/nitin/bridge/javacpp-mvn-simple-demo/target/classes/somepackage/jniMultiplyDemo.cpp:1054:6: error: ‘ptr’ was not declared in this scope
ptr = ()jlong_to_ptr(env->GetLongField(obj, JavaCPP_addressFID));
^~~
/home/necuser/nitin/bridge/javacpp-mvn-simple-demo/target/classes/somepackage/jniMultiplyDemo.cpp:1054:13: error: expected primary-expression before ‘)’ token
ptr = ()jlong_to_ptr(env->GetLongField(obj, JavaCPP_addressFID));

I am new to JavaCPP. Please help.

Nitin Trivedi
  • 31
  • 8
  • You're missing an "include" in the @Platform annotation. Try to add it. – Samuel Audet May 28 '20 at 22:25
  • 1
    @SamuelAudet Thank you sir ! This worked : @Platform(include="somepackage/export.cpp", library="abc") and making the declaration static : public native static void multply(int a, float b) – Nitin Trivedi May 29 '20 at 05:28

0 Answers0