3D Shooters Episode II: Doom for Android - Pro Android Games - page 254

To create a Java byte array, you can use jbyteArray ARRAY = (*env)->
NewByteArray(env, SIZE) , where the words byte / Byte can be replaced with
boolean / Boolean , int / Int , object / Object , and other primitive types, depending on
your needs.

•

To insert data into the array, use (*env)->SetByteArrayRegion(env, ARRAY,
START, SIZE, (jbyte *) C_ARRAY) , where Byte can be replaced with any Java
primitive type.

•

To call a static void method, use (*env)->CallStaticVoidMethod(env, CLASS,
METHOD_ID, ARG1, ARG2,…) .

•

To release resources for an array, use (*env)->DeleteLocalRef(env, ARRAY) . •

Listing 7-17. Cascading Sound and Music Requests Back to Java

/**
* Fires multiple times when a sound is played
* @param name Sound name
* @param volume
*/
void jni_start_sound (const char * name, int vol)
{
/*
* Attach to the curr thread; otherwise we get JNI WARNING:
* threadid=3 using env from threadid=15 which aborts the VM
*/
JNIEnv *env;

if ( !g_VM) {
return;
}

(*g_VM)->AttachCurrentThread (g_VM, (void **) &env, NULL);

if ( jStartSoundMethod == 0 ) {
jni_printf("BUG: Invalid Doom JNI method OnStartSound %s"
, CB_CLASS_SS_SIG);
return ;
}

// Create a new char[] used by jni_send_pixels
// Used to prevent JNI ref table overflows
int iSize = strlen(name);
jbyteArray jSound = (*env)-> NewByteArray(env, iSize);

(*env)->SetByteArrayRegion(env, jSound, 0, iSize, (jbyte *) name);

// Call Java method
(*env)->CallStaticVoidMethod(env, jNativesCls
, jStartSoundMethod
, jSound //(*env)->NewStringUTF(env, name)