Get android Ethernet MAC Address (not wifi interface)

This is my solution based on the Joel F answer. Hope it helps someone!

/* * Load file content to String */public static String loadFileAsString(String filePath) throws java.io.IOException{    StringBuffer fileData = new StringBuffer(1000);    BufferedReader reader = new BufferedReader(new FileReader(filePath));    char[] buf = new char[1024];    int numRead=0;    while((numRead=reader.read(buf)) != -1){        String readData = String.valueOf(buf, 0, numRead);        fileData.append(readData);    }    reader.close();    return fileData.toString();}/* * Get the STB MacAddress */public String getMacAddress(){    try {        return loadFileAsString("/sys/class/net/eth0/address")            .toUpperCase().substring(0, 17);    } catch (IOException e) {        e.printStackTrace();        return null;    }}

Assuming your ethernet interface is eth0, try opening and reading the file /sys/class/net/eth0/address.

this way to use java fix it; maybe can help you

NetworkInterface netf = NetworkInterface.getByName("eth0");byte[] array = netf.getHardwareAddress();StringBuilder stringBuilder = new StringBuilder("");String str = "";for (int i = 0; i < array.length; i++) {    int v = array[i] & 0xFF;    String hv = Integer.toHexString(v).toUpperCase();    if (hv.length() < 2) {        stringBuilder.append(0);    }    stringBuilder.append(hv).append("-");                   }str = stringBuilder.substring(0, stringBuilder.length()- 1);