jni jnienv NewFloatArray example c c++ java

New<PrimitiveType>Array Routines - NewFloatArray

ArrayType New<PrimitiveType>Array(JNIEnv *env, jsize length);

A family of operations used to construct a new primitive array object. Table 4-8 describes the specific primitive array constructors. You should replace New<PrimitiveType>Array with one of the actual primitive array constructor routine names from the following table, and replace ArrayType with the corresponding array type for that routine.(NewFloatArray)

Table 4-8a New<PrimitiveType>Array Family of Array Constructors

New<PrimitiveType>Array Routines	Array Type
NewBooleanArray()	jbooleanArray
NewByteArray()	jbyteArray
NewCharArray()	jcharArray
NewShortArray()	jshortArray
NewIntArray()	jintArray
NewLongArray()	jlongArray
NewFloatArray()	jfloatArray
NewDoubleArray()	jdoubleArray

LINKAGE:

Indices in the JNIEnv interface function table.

Table 4-8b New<PrimitiveType>Array Family of Array Constructors

New<PrimitiveType>Array Routines	Index
NewBooleanArray()	175
NewByteArray()	176
NewCharArray()	177
NewShortArray()	178
NewIntArray()	179
NewLongArray()	180
NewFloatArray()	181
NewDoubleArray()	182

PARAMETERS of NewFloatArray

env: the JNI interface pointer.

length: the array length.

RETURNS of NewFloatArray

Returns a Java array, or NULL if the array cannot be constructed.

Example of NewFloatArray


int tempSize = mParticleSystem->mSizeOfSystem*2;
jfloatArray jArray = env->NewFloatArray(tempSize);

if (jArray != NULL)
{
    env->SetFloatArrayRegion(jArray, 0, tempSize, mParticleSystem->mParticlePositions);
}
return jArray;

If it is not float array then use following code, no need to create additional float array:

int tempSize = mParticleSystem->mSizeOfSystem*2;
jfloatArray jArray = env->NewFloatArray(tempSize);

if (jArray != NULL)
{
    if (float* ptr = env->GetFloatArrayElements(jArray, NULL))
    {
        for (int i=0; i<tempSize; i++)
        {
            ptr[i] = mParticleSystem->mParticlePositions[i];
        }
        env->ReleaseFloatArrayElements(jArray, ptr, JNI_COMMIT);
    }
}

return jArray;