Tests/Java/ResourceNS.java

import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.BufferedReader;
import java.io.IOException;

class ResourceNS
{
    public static void main(String args[])
    {
        ResourceNS res = new ResourceNS();
        res.displayResourceText();
    }

    public void displayResourceText()
    {
        /*
         * Since Java SE 9, invoking getResourceXXX on a class in a named
         * module will only locate the resource in that module, it will
         * not search the class path as it did in previous release. So when
         * you use Class.getClassLoader().getResource() it will attempt to
         * locate the resource in the module containing the ClassLoader,
         * possibly something like:
         *      jdk.internal.loader.ClassLoaders.AppClassLoader
         * which is probably not the module that your resource is in, so it
         * returns null.
         *
         * You have to make java 9+ search for the file in your module.
         * Do that by changing Class to any class defined in your module in
         * order to make java use the proper class loader.
        */

        // Namespaces are relative, use leading '/' for full namespace
        InputStream is =
            ResourceNS.class.getResourceAsStream("/ns/ns1/HelloWorld.txt");
        // C++:    cout << is.readline();    // oh, well !
        InputStreamReader isr = new InputStreamReader(is);
        BufferedReader reader = new BufferedReader(isr);
        String out = "";
        try{
            out = reader.readLine();
        } catch(IOException e) {
            e.printStackTrace();
            System.out.println(e);
        }

        System.out.println(out);
    }
}