Kotlin program to get system MAC address

package com.includehelp

import java.net.InetAddress
import java.net.NetworkInterface

//Function to get System MAC
fun getSystemMac(): String? {
    return try {
        val OSName = System.getProperty("os.name")     //Get Operating System Name
        if (OSName.contains("Windows")) {
            getMAC4Windows()                           // Call if OS is Windows
        } else {
            var mac = getMAC4Linux("eth0")
            if (mac == null) {
                mac = getMAC4Linux("eth1")
                if (mac == null) {
                    mac = getMAC4Linux("eth2")
                    if (mac == null) {
                        mac = getMAC4Linux("usb0")
                    }
                }
            }
            mac
        }
    } catch (E: Exception) {
        System.err.println("System Mac Exp : " + E.message)
        null
    }
}

/**
 * Method for get MAc of Linux Machine
 */
fun getMAC4Linux(name: String): String? {
    return try {
        val network = NetworkInterface.getByName(name)
        val mac = network.hardwareAddress
        val sb = StringBuilder()
        for (i in mac.indices) {
            sb.append(String.format("%02X%s", mac[i], if (i < mac.size - 1) "-" else ""))
        }
        sb.toString()
    } catch (E: Exception) {
        System.err.println("System Linux MAC Exp : " + E.message)
        null
    }
}

/**
 * Method for get Mac Address of Windows Machine
*/
fun getMAC4Windows(): String? {
    return try {
        val addr = InetAddress.getLocalHost()
        val network = NetworkInterface.getByInetAddress(addr)
        val mac = network.hardwareAddress
        val sb = StringBuilder()
        for (i in mac.indices) {
            sb.append(String.format("%02X%s", mac[i], if (i < mac.size - 1) "-" else ""))
        }
        sb.toString()
    } catch (E: Exception) {
        System.err.println("System Windows MAC Exp : " + E.message)
        null
    }
}


//Main Function, Entry Point of Program
fun main(args: Array<String>) {

    //Call Function to get MAC Address
    val macAddress = getSystemMac()

    //Print MAC Address
    println("System Mac Address : $macAddress")
}

Output

System Mac Address : 02-12-FE-11-00-05