I have a C++ function in a .cpp file; say unsigned char *myFunc().
How can I convert that array in a byte[] array in Java?
I mean, in Java, I want to do something like:
byte[] b = myLib.myFunc();
I am using SWIG and appearently I need to define a kind of conversion from unsigned char to byte in the .i file, but I don't know exactly how.
Thank you in advance
Try returning a std::string instead of unsigned char* and %include <std_string.i> in your .i file. Thanks to std_string.i typemaps, you might end up with a byte[] on the receiving side. If you can change the return type of myFunc then create a wrapper via %inline, something like
%inline %{
std::string myFuncStr() { return myFunc(); }
%}
If you want you can %rename myFuncStr to myFunc, thus hiding the fact that the myFunc exported to Java is actually a wrapper to the real myFunc.
If that doesn't work, Flexo's solution to Swig: convert return type std::string(binary) to java byte[] likely will.
unsigned char* contains any ASCII character also greater than 128I don't know about using swig but I do know that if you change your mind and want don't mind using JNI, then the following will work:
On the C++ side:
extern "C" jbyteArray JNIEXPORT Java_myPackageName_MyClassName_getByteArray(JNIEnv* env, jobject obj)
{
jbyteArray byte_arr = env->NewByteArray(size);
jbyte bytes[25]; //Some byte array you want to give to java. Could be an unsigned char[25].
for (int i = 65; i < 90; ++i) //filling it with some A-Z ASCII characters.
{
bytes[i - 65] = i;
}
env->SetIntArrayRegion(byte_arr, 0, 25, &bytes[0]); //Fill our byte array
return byte_arr; //return the byte array..
}
on the Java side:
package myPackageName;
class MyClassName
{
static {
System.loadLibrary("myByteArrayModule");
}
public static native byte[] getByteArray();
}
