How to run applet with policy permissions in Java to read the MAC address

I'm trying to develop an applet in NetBeans which can read the MAC address.

So here is my directory structure

Here is my UPDATED Code

MacAddrApplet.java

import java.awt.Graphics;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.ArrayList;
import java.util.Enumeration;
import javax.swing.JApplet;

/**
 *
 * @author jay.patel
 */
public class MacAddressApplet extends JApplet {

    public static String getMacFromInterface(NetworkInterface ni) throws SocketException {
        byte mac[] = ni.getHardwareAddress();

        if (mac != null) {
            StringBuilder macAddress = new StringBuilder("");
            String sep = "";
            for (byte o : mac) {
                macAddress.append(sep).append(String.format("%02X", o));
                sep = ":";
            }
            return macAddress.toString();
        }

        return "";
    }

    public static String[] getInterfaces() {
        try {
            Enumeration<NetworkInterface> nis = NetworkInterface.getNetworkInterfaces();

            ArrayList<String> result = new ArrayList<String>();
            while (nis.hasMoreElements()) {
                NetworkInterface ni = nis.nextElement();
                if (ni.isUp() && !ni.isLoopback() && !ni.isVirtual()) {
                    String mac = getMacFromInterface(ni);
                    String str = ni.getDisplayName() + ";" + mac;
                    result.add(str);
                }
            }
            return result.toArray(new String[0]);
        } catch (SocketException e) {
            System.out.println("SocketException:: " + e.getMessage());
        } catch (Exception e) {
            System.out.println("Exception:: " + e.getMessage());
        }

        return new String[0];
    }

    public static String getInterfacesJSON() {
        try {
            String macs[] = getInterfaces();

            String sep = "";
            StringBuilder macArray = new StringBuilder("['");
            for (String mac : macs) {
                macArray.append(sep).append(mac);
                sep = "','";
            }
            macArray.append("']");

            return macArray.toString();
        } catch (Exception e) {
            System.out.println("Exception:: " + e.getMessage());
        }

        return "[]";
    }

    @Override
    public void paint(Graphics g) {
        super.paint(g);
         AccessController.doPrivileged(new PrivilegedAction() {
            public Object run() {
                String macs[] = getInterfaces();

                for (String mac : macs) {
                    System.out.println(" Interfaces = " + mac);
                }

                System.out.println(" Interfaces JSON = " + getInterfacesJSON());
                g.drawString("MAC: " + getInterfacesJSON(), 100, 100);
                return null;
            }
        });

    }

}

MacAddrApplet.html

<HTML>
<HEAD>
    <TITLE>Applet HTML Page</TITLE>
</HEAD>
<BODY>

    <H3><HR WIDTH="100%">Applet HTML Page<HR WIDTH="100%"></H3>

    <P><APPLET codebase="classes" code="MacAddrApplet.class" width=350 height=200></APPLET></P>

    <HR WIDTH="100%"><FONT SIZE=-1><I>Generated by NetBeans IDE</I></FONT>
</BODY>

applet.policy

grant {
permission java.security.AllPermission;
};

When I try to run my applet from Run -> Run File it works perfectly fine and shows my Mac address in it, with this log that I'm printing

Interfaces = en1;XX:XX:XX:XX:XX:XX
Interfaces JSON = ['en1;XX:XX:XX:XX:XX:XX']

But when I try to run it using

appletviewer build/MacAddrApplet.html

it prints

Interfaces = en1;
Interfaces JSON = ['en1;']

How can I solve this issue??

P.S. I think it's happening because it's not using the permissions of applet.policy

Solution

Eventually I figured out what's wrong with the terminal command

appletviewer build/MacAddrApplet.html

because if you see the project.properties file located in nbproject folder, at the end part, you'll see

run.jvmargs=-Djava.security.policy=applet.policy

So when I run the applet using Run -> Run File Netbeans internally took care of everything and hence the applet is running perfectly fine.

But, in case of the terminal, I need to specify the policy file explicitly (This is what I want to know when I asked the question!), So run the applet with this command and it will work fine...

appletviewer -J-Djava.security.policy=applet.policy build/MacAddrApplet.html