Re: [Interest] (JNI ERROR) jbytearray -> java.lang.String[] - What am I doing wrong here?

[Jason H]

I'm not familiar with that, jbteArray, but in attemping your challenge, I saw:

 

qjniEnv->SetByteArrayRegion(jdata, 0, _size, reinterpret_cast<jbyte *>(foo));

 

but saw this in the docs: 

void Set<PrimitiveType>ArrayRegion(JNIEnv *env, ArrayType array, jsize start, jsize len, NativeType *buf);

 

is jdata your jni env?

Sent: Friday, January 25, 2019 at 1:13 PM
From: "René Hansen" <ren...@gmail.com>
To: interest <interest@qt-project.org>
Subject: [Interest] (JNI ERROR) jbytearray -> java.lang.String[] - What am I doing wrong here?

All I want to do is send some bytes from Qt to Java, but I'm running into an annoying problem, where my jbyteArray gets turned into java.lang.String[] in mid-flight:

 

E art     : JNI ERROR (app bug): attempt to pass an instance of java.lang.String[] as argument 1 to int Foo.bar(byte[])

F art     : art/runtime/java_vm_ext.cc:410] JNI DETECTED ERROR IN APPLICATION: bad arguments passed to int Foo.bar(byte[]) (see above for details)

F art     : art/runtime/java_vm_ext.cc:410]     from void org.qtproject.qt5.android.QtNative.runPendingCppRunnables()

F art     : art/runtime/java_vm_ext.cc:410] "main" prio=5 tid=1 Runnable

...

 

Here's a minimal example; just a simple auto test project:

 

TestJNI.pro:

 

QT += testlib androidextras

QT -= gui

 

CONFIG += qt console warn_on depend_includepath testcase

CONFIG -= app_bundle

 

TEMPLATE = app

 

SOURCES +=  tst_test_jni.cpp

 

ANDROID_PACKAGE_SOURCE_DIR = $$PWD

 

DISTFILES += \

    src/Foo.java

 

tst_test_jni.cpp:
 

#include <QtTest>

#include <QAndroidJniEnvironment>

#include <QtAndroid>

 

class test_jni : public QObject

{

    Q_OBJECT

 

private slots:

    void test_case1();

};

 

void test_jni::test_case1()

{

  QAndroidJniEnvironment qjniEnv;

  jsize _size = static_cast<jsize>(5);

  jbyteArray jdata = qjniEnv->NewByteArray(_size);

  jint result;

 

  if (jdata == nullptr)

    QFAIL("Failed creating new jbyteArray");

 

  if (qjniEnv->GetArrayLength(jdata) != _size)

  {

    qjniEnv->DeleteLocalRef(jdata);

    QFAIL("Failed to allocate entire array through JNI");

  }

 

  // Lorem

  char foo[] = { 0x4c, 0x6f, 0x72 ,0x65, 0x6d };

 

  qjniEnv->SetByteArrayRegion(jdata, 0, _size, reinterpret_cast<jbyte *>(foo));

 

  QtAndroid::runOnAndroidThread([jdata] {

    QAndroidJniObject::callStaticMethod<jint>(

          "Foo",

          "bar",

          "([B)I",

          jdata);

  });

 

  QCOMPARE(result, 42);

}

 

QTEST_APPLESS_MAIN(test_jni)

 

#include "tst_test_jni.moc"

 

Foo.java:

 

public class Foo {

  static int bar(byte baz[]) {

      return 42;

  }

}

 

Have I missed something very basic here?

 

 

Best regards,

 

René Hansen

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