QAndroidJniObject::callStaticMethod is returning 0.

Ibrahim

Hi; I am writing code about call a Java function from C++ but QAndroidJniObject is returning 0 value. (Note: I included QT += androidextras in .pro file).

// Java Code
package com.example.classes;
public class JavaClassExample {
  public static int factorial(int n) {
    return (n > 1) ? n * factorial(n - 1) : 1;
  }
}

// C++ Code
#include <QMessageBox>
#include <QAndroidJniObject>
...
int factorial(int n)
{
  return QAndroidJniObject::callStaticMethod<jint>(
        "com/example/classes/JavaClassExample",
        "factorial",
        "(I)I",
        n);
}
...
QMessageBox::information(this, tr("Factorial"), QString::number(factorial(7)));
// Output Always -> 0

I am learning from here. Thanks.

Ibrahim

Structure of my project and structure notification example of Qt: IMAGE LINK. I put .java file in Other Files directory but Qt example put .java file in Other file/android-sources/src/org/qtproject/example/notification directory. When I clicked Projects -> Build Android APK -> Create Templates button, created is Other files/android (like in image). Can be problem is so?

Qojote

Hi.
I am working on a quite similar problem, so maybe this could help:

Double-check your package names, i guess its good when the package name in your AndroidManifest.xml equals the packe in your Java class.
I was able to call functions from java classes like shown on slide 42 of your posted link (extending with QtActivity -> remember to change your manifest!).

Best regards

Ibrahim

@Qojote Thanks. I solved this problem: I put .java file in android/src/com/example/classes directory and it is running. Alright, how can I create src/com/example/classes directory? I do by manuel but this directory do not see in Qt Creator. Actually how can I create this directory from Qt Creator? Thanks.
Edit:
If you want to see directories, you must append this command in the .pro file:
DISTFILES += path/to/directory
Then close project and open project again.

Solved QAndroidJniObject::callStaticMethod is returning 0.