Android | DexClassLoader, ClassNotFound exception

So i'm trying to load a class that i wrote from my application, but im receiving ClassNotFound exception.

class:

public class myclass{
    public String doSomething()
    {
        return "Hello from myclass";
    }
}

I than creates a jar file using the following commands:

javac myclass.java
jar cvf myclass.jar myclass.class

My next step is to creates a classes.dex for my jar file, and add it to the jar:

dx --dex --output=classes.dex myclass.jar
aapt add myclass.jar classes.dex

Untill now everything works great, no errors.

At the end of this step, my jar file is as follows:

myclass.jar
    -> classes.dex
    -> myclass.class
    -> META-INF
       -> MANIFEST.MF

My manifest file contains this lines:

Manifest-Version: 1.0
Created-By: 1.7.0_79 (Oracle Corporation)

Now inside my application i'm doing this:

private void activate()
{
    try {
        URL url;
        final String libPath = Environment.getExternalStorageDirectory() + "/myclass.jar";
        final File tmpDir = getDir("dex", 0);

        final DexClassLoader classloader = new DexClassLoader(libPath, tmpDir.getAbsolutePath(), null, this.getClass().getClassLoader());
        final Class<Object> classToLoad = (Class<Object>) classloader.loadClass("myclass");

        final Object myInstance  = classToLoad.newInstance();
        final Method doSomething = classToLoad.getMethod("doSomething");

        String result = (String)doSomething.invoke(myInstance);
        Toast.makeText(MainActivity.this, String.valueOf(result), Toast.LENGTH_SHORT).show();
    } catch (Exception e) {
        e.printStackTrace();
    }
}

Notes:

1. I copied the myclass.jar file to the

Environment.getExternalStorageDirectory()

directory and i confirmed that the application is reading the file correctly.

2. I have set the needed permissions in the manifest file(Read&Write to external storage)

The line that gives me the error is:

final Class<Object> classToLoad = (Class<Object>) classloader.loadClass("myclass");

The error:

Didn't find class "myclass" on path: DexPathList[[zip file "/storage/emulated/0/myclass.jar"],nativeLibraryDirectories=[/vendor/lib, /system/lib]]

This are the suppressed exceptions:

java.io.IOException: No original dex files found for dex location /storage/emulated/0/myclass.jar

java.lang.ClassNotFoundException: Didn't find class "myclass" on path: DexPathList[[dex file "/data/data/hayzohar.testingclassloaders/files/instant-run/dex/slice-support-annotations-23.3.0_d42c1a3ea55c8ce3f82fc6c8adde2e2271b97d01-classes.dex", dex file "/data/data/hayzohar.testingclassloaders/files/instant-run/dex/slice-slice_9-classes.dex", dex file "/data/data/hayzohar.testingclassloaders/files/instant-run/dex/slice-slice_8-classes.dex", dex file "/data/data/hayzohar.testingclassloaders/files/instant-run/dex/slice-slice_7-classes.dex", dex file "/data/data/hayzohar.testingclassloaders/files/instant-run/dex/slice-slice_6-classes.dex", dex file "/data/data/hayzohar.testingclassloaders/files/instant-run/dex/slice-slice_5-classes.dex", dex file "/data/data/hayzohar.testingclassloaders/files/instant-run/dex/slice-slice_4-classes.dex", dex file "/data/data/hayzohar.testingclassloaders/files/instant-run/dex/slice-slice_3-classes.dex", dex file "/data/data/hayzohar.testingclassloaders/files/instant-run/dex/slice-slice_2-classes.dex", dex file "/data/data/hayzohar.testingclassloaders/files/instant-run/dex/slice-slice_1-classes.dex", dex file "/data/data/hayzohar.testingclassloaders/files/instant-run/dex/slice-slice_0-classes.dex", dex file "/data/data/hayzohar.testingclassloaders/files/instant-run/dex/slice-internal_impl-23.3.0_75eb76bdd9c015b48a4280667bfd60eddc59734a-classes.dex", dex file "/data/data/hayzohar.testingclassloaders/files/instant-run/dex/slice-com.android.support-support-vector-drawable-23.3.0_0a5b88d45587f58c7ea931638fd9c9d6c4641bc7-classes.dex", dex file "/data/data/hayzohar.testingclassloaders/files/instant-run/dex/slice-com.android.support-support-v4-23.3.0_a0a32aaad2874bf2c15ffa67543dfe5af5b91a95-classes.dex", dex file "/data/data/hayzohar.testingclassloaders/files/instant-run/dex/slice-com.android.support-appcompat-v7-23.3.0_eae70f9c3956161dfb324670cb40cb42e6e1b16a-classes.dex", dex file "/data/data/hayzohar.testingclassloaders/files/instant-run/dex/slice-com.android.support-animated-vector-drawable-23.3.0_d4513d6bda757fa567bc4d7ea3e4bb7cbd09c077-classes.dex"],nativeLibraryDirectories=[/data/app/hayzohar.testingclassloaders-2/lib/x86, /vendor/lib, /system/lib]]

What am i doing wrong?