Need help on returning arrays from C++ to Java

Question

Hi all, I hava a C++ application that contains a method that will return a float array to Java. I was able to write the Java Code, the JNI code to call the C++ method and compile them successfully. However on calling the native method from Java, the data in the array returned was not what I want. Please look through my code and see what is wrong with it.
My Java Code:
public native float[] Statistics(int inputKey); // This is the native method
public float[] Stats(int k){ //Java method to call the native method so that I can use it in a Bean for a JSP.
inputKey = k;
float[] p = new float[4];
p = Statistics(inputKey);
return p;
For this native method, an integer is passed from Java to the native side and the native method will use this integer to generate a float array size of 4 and populate it with data and return it back to Java.
My JNI code
extern "C"
JNIEXPORT jfloatArray JNICALL
Java_com_jspsmart_upload_FinalWaterMark_Statistics(JNIEnv *env, jobject obj, jint inputKey)
     jfloatArray floatArray = env->NewFloatArray(4); //This creates a new Java floatArray to store the C++ array
     CWatermarker2App p; // This is the C++ class to be used
     jfloat *stats = p.OnWatermarkStatistics(inputKey) // The C++ method returns a float pointer for an array of size 4
     env->SetFloatArrayRegion(floatArray, 0 , 4 , stats); //storing the C++ float array into the Java float Array
     return floatArray; // return the Array to Java
In this example, I should have the data returned as [4952.0 2529.0 1706.0 33.6] in the array.
But i am getting junk instead like 2.53E-23, 1.402E-15 etc..
Is this a type conversion mistake?
Please help!

Answer 1

The first thing I notice - probably not the problem - is the line defining p. There is no reason to define this as an array of size 4, because the return from the native method is going to wipe that definition, replacing it with the return value of the native method. Alternatives:
1. float[] p = null.
2. float[] p = Statistics(inputKey);
3. return Statistics(k);