将C ++基本类型向量转换为Java基本类型数组

Question

I'm using a third party C++ API for my project and it has functions with return values with types std::vector<int> , std::vector<bool> , std::vector<double> . I need to pass variables with these types to Java. So I'm using JNI and my function has return values with types jintArray , jbooleanArray , jdoubleArray .

I'm using following code to convert double type:

std::vector<double> data;
//fill data
jdouble *outArray = &data[0];
jdoubleArray outJNIArray = (*env).NewDoubleArray(data.size());  // allocate
if (NULL == outJNIArray) return NULL;
(*env).SetDoubleArrayRegion(outJNIArray, 0 , data.size(), outArray);  // copy
return outJNIArray;

I've no problem with this code block. But when I want to do this for int and bool types there is a problem at the following:

std::vector<int> data;
//fill data
jint *outArray = &data[0];

and

std::vector<bool> data;
//fill data
jboolean *outArray = &data[0];

The problem is with definitions of jint and jboolean , since:

typedef long            jint;
typedef unsigned char   jboolean;

and for jdouble :

typedef double          jdouble;

As, you can see my convenient solution for double doesn't work for int and bool types since their typedefs doesn't match.

So, my question is how can I do this conversion for all primitive types conveniently ?

Thanks in advance

Answer 1

Since the data types might have different sizes you have to copy the vector. The simplest way to do this is

std::vector<jboolean> tmp(data.begin(), data.end());
jboolean *outArray = &tmp[0];

Of course, you can allocate the jBooleanArray and set the elements in a for loop or write a wrapper for it that behaves like an STL container.