java.lang.ClassNotFoundException when trying basic JNI example

[Diracsbracket]

Hi,
I am trying out a basic JNI example (Fibonacci example in https://conf.qtcon.org/system/attachments/132/original/QtCon16.pdf%3F1473147092) but I get the following build error:

W System.err: java.lang.ClassNotFoundException: Didn't find class "com.example.test.JniTest" on path: DexPathList[[],nativeLibraryDirectories=[/system/lib, /vendor/lib]]
W System.err: 	at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:125)
W System.err: 	at java.lang.ClassLoader.loadClass(ClassLoader.java:379)
W System.err: 	at java.lang.ClassLoader.loadClass(ClassLoader.java:312)
D libTestApp: (null):0 ((null)): Fibonacci:  0

I have created the Java file JniTest.java as follows:

public class JniTest
{
    public static int fibonacci(int n)
    {
        if(n<0)
            return -1;
        else if(n==0 || n==1)
            return n;

        return fibonacci(n-1)+fibonacci(n-2);
    }
}

The java file is stored as android-source/src/com/example/test/JniTest.java and added to the Qt Creator project.

In a .cpp file, I have:

int AndroidInterface::fibonacci(int n)
{
    return QAndroidJniObject::callStaticMethod<jint>("com/example/test/JniTest"
                                                 , "fibonacci"
                                                 , "(I)I"
                                                 , n);
}

and in my main.cpp:

  AndroidInterface android;
  ...
  qDebug() << "Fibonacci: " << android.fibonacci(3);
  ...
   return app.exec();

However, this results in the errors shown above. Why?
Tried it on Qt 5.10.1, on a virtual Android device.

[Pablo J. Rogina]

@Diracsbracket if JniTest.java source code is completely displayed in the post, it looks to me that you're missing 'package' (see slide 34 from your reference):

package com.example.test;

[Diracsbracket]

@Pablo-J.-Rogina said in java.lang.ClassNotFoundException when trying basic JNI example:

it looks to me that you're missing 'package'

You're absolutely right!
This is a little bit embarrassing... "They have eyes, yet they don't see...".

Thank you for your kind help, and for a good lesson learned. I'll never again forget
to put the package declaration at the top of a Java file...

[Surajkumar Tanurkar]

i am also getting same error my signal and slot working well but class not found exception error is there
i have declared package name in java file in manifest file too