[SOLVED] Android: How to get a byte array from java?

ltr6

My java class returns a byte[] and I need to access it in qt.
This is what I've tried.

@
QByteArray myQtClass::getArrayFromJava(QString id, QString name)
{
jstring jid = env->NewStringUTF(id.toStdString().c_str());
jstring jname = env->NewStringUTF(name.toStdString().c_str());

 jbyteArray myArray = QAndroidJniObject::callStaticMethod<jbyteArray>("com/my/JavaClass", "getArray", "(Ljava/lang/String;Ljava/lang/String;)B]", jid, jname);

// Convert to bytearray

}
@

The following error is produced:

error: undefined reference to '_jbyteArray* QAndroidJniObject::callStaticMethod<_jbyteArray*>(char const*, char const*, char const*, ...)'

Is there a correct way to do it?

The bytearray is a jpeg image. I have thought about converting it to a Base64 encoded string and then back, but that might be pretty expensive when dealing with a large number of files.

Any help would be appreciated.

Iktwo

I'm working on a Qt android launcher, here's how I do it

@
public static byte[] getApplicationIcon(String packageName) {
..
return icon;
}
@

@
..
QAndroidJniObject applicationIcon = QAndroidJniObject::callStaticObjectMethod("com/iktwo/utils/QPackageManager",
"getApplicationIcon",
"(Ljava/lang/String;)[B", QAndroidJniObject::fromString(id).object<jstring>());

if (!iconDataArray) {
qDebug() << Q_FUNC_INFO << "No icon data";

    return image;
}

jsize iconSize = env->GetArrayLength(iconDataArray);

if (iconSize > 0) {
    jbyte *icon = env->GetByteArrayElements(iconDataArray, false);
    image = QImage(QImage::fromData((uchar*) icon, iconSize,"PNG"));
    env->ReleaseByteArrayElements(iconDataArray, icon, 0);
}

..
@

ltr6

Sorry, but I don't understand. You have a QAndroidJniObject called applicationIcon, which is supposed to be the bytearray? But then where does the iconDataArray come from? Did you leave out some conversion that happens in between from applicationIcon -> iconDataArray?

Iktwo

I'm sorry.. this is my function
@
QAndroidJniObject appIcon = QAndroidJniObject::callStaticObjectMethod("com/iktwo/utils/QPackageManager",
"getApplicationIcon",
"(Ljava/lang/String;)[B",
QAndroidJniObject::fromString(id).object<jstring>());

QAndroidJniEnvironment env;
jbyteArray iconDataArray = appIcon.object<jbyteArray>();

if (!iconDataArray) {
    qDebug() << Q_FUNC_INFO << "No icon data";

    return image;
}

jsize iconSize = env->GetArrayLength(iconDataArray);

if (iconSize > 0) {
    jbyte *icon = env->GetByteArrayElements(iconDataArray, false);
    image = QImage(QImage::fromData((uchar*) icon, iconSize,"PNG"));
    env->ReleaseByteArrayElements(iconDataArray, icon, JNI_ABORT);
}

@

ltr6

Thank you! It works.