Simplest way to pass float[][] to C++ via JNI

Question

In my Java code I have a 2D float array float[x][4] floatArray. Here x can be between 1 and 25. I have to pass this 2D float array to a C++<

Answer 1

Something like this should work:

jboolean MyJNIMethod(JNIEnv * env, jobject obj, jobjectArray myArray)
{
  int len1 = env -> GetArrayLength(myArray);
  jfloatArray dim=  (jfloatArray)env->GetObjectArrayElement(myArray, 0);
  int len2 = env -> GetArrayLength(dim);
  float **localArray;
  // allocate localArray using len1
  localArray = new float*[len1];
  for(int i=0; iGetObjectArrayElement(myArray, i);
     jfloat *element=env->GetFloatArrayElements(oneDim, 0);
     //allocate localArray[i] using len2
     localArray[i] = new float[len2];
     for(int j=0; j

Note that this is outline. It won't compile ;) (I wrote it in this overstacks' editor)

In your class you should declare native method:

 public native void myJNIMethod(float[][] m);

and in your c code corresponding:

JNIEXPORT jboolean JNICALL Java_ClassName_methodName (JNIEnv *, jobject, jobjectArray);

Here is JNI array operations documentation.