Get<PrimitiveType>ArrayElements Routines - GetShortArrayElements
NativeType
*Get<PrimitiveType>ArrayElements(JNIEnv *env,ArrayType array, jboolean *isCopy);
A family of functions that returns the body of the primitive array. The result is valid until the correspondingRelease
<PrimitiveType>ArrayElements() function is called. Since the returned array may be a copy of the Java array, changes made to the returned array will not necessarily be reflected in the original array until Release<PrimitiveType>ArrayElements() is called. (GetShortArrayElements)
If
isCopy is not NULL, then *isCopy is set to JNI_TRUE if a copy is made; or it is set to JNI_FALSE if no copy is made.
The following table describes the specific primitive array element accessors. You should make the following substitutions: (GetShortArrayElements)
- Replace Get<PrimitiveType>ArrayElements with one of the actual primitive element accessor routine names from the table.
- Replace ArrayType with the corresponding array type.
- Replace NativeType with the corresponding native type for that routine.
Regardless of how boolean arrays are represented in the Java VM,
GetBooleanArrayElements() always returns a pointer tojbooleans, with each byte denoting an element (the unpacked representation). All arrays of other types are guaranteed to be contiguous in memory.
Table 4-9a Get<PrimitiveType>ArrayElements Family of Accessor Routines
LINKAGE:
Indices in the JNIEnv interface function table.
Table 4-9b Get<PrimitiveType>ArrayElements Family of Accessor Routines
PARAMETERS of GetShortArrayElements
env: the JNI interface pointer.array: a Java string object.isCopy: a pointer to a boolean.RETURNS of GetShortArrayElements
Returns a pointer to the array elements, or
NULL if the operation fails.
Example of GetShortArrayElements
JNIEXPORT jshortArray JNICALL Java_speex_EchoCanceller_process
(JNIEnv * env, jobject jObj, jshortArray input_frame, jshortArray echo_frame)
{
//create native shorts from java shorts
jshort *native_input_frame = (*env)->GetShortArrayElements(env, input_frame, NULL);
jshort *native_echo_frame = (*env)->GetShortArrayElements(env, echo_frame, NULL);
//allocate memory for output data
jint length = (*env)->GetArrayLength(env, input_frame);
jshortArray temp = (*env)->NewShortArray(env, length);
jshort *native_output_frame = (*env)->GetShortArrayElements(env, temp, 0);
//call echo cancellation
speex_echo_cancellation(st, native_input_frame, native_echo_frame, native_output_frame);
//preprocess output frame
speex_preprocess_run(den, native_output_frame);
//convert native output to java layer output
jshortArray output_shorts = (*env)->NewShortArray(env, length);
(*env)->SetShortArrayRegion(env, output_shorts, 0, length, native_output_frame);
//cleanup and return
(*env)->ReleaseShortArrayElements(env, input_frame, native_input_frame, 0);
(*env)->ReleaseShortArrayElements(env, echo_frame, native_echo_frame, 0);
(*env)->ReleaseShortArrayElements(env, temp, native_output_frame, 0);
return output_shorts;
}
