How to find MAC address of an Android device programmatically

Question

WifiManager wifiManager = (WifiManager) getApplicationContext().getSystemService(Context.WIFI_SERVICE);
WifiInfo wInfo = wifiManager.getConnectionInfo();
String macAddress = wInfo.getMacAddress(); 

Also, add below permission in your manifest file

<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>

Please refer to Android 6.0 Changes.

To provide users with greater data protection, starting in this release, Android removes programmatic access to the device’s local hardware identifier for apps using the Wi-Fi and Bluetooth APIs. The WifiInfo.getMacAddress() and the BluetoothAdapter.getAddress() methods now return a constant value of 02:00:00:00:00:00.

To access the hardware identifiers of nearby external devices via Bluetooth and Wi-Fi scans, your app must now have the ACCESS_FINE_LOCATION or ACCESS_COARSE_LOCATION permissions.

See this post where I have submitted Utils.java example to provide pure-java implementations and works without WifiManager. Some android devices may not have wifi available or are using ethernet wiring.

Utils.getMACAddress("wlan0");
Utils.getMACAddress("eth0");
Utils.getIPAddress(true); // IPv4
Utils.getIPAddress(false); // IPv6 

With this code you will be also able to get MacAddress in Android 6.0 also

public static String getMacAddr() {
    try {
        List <NetworkInterface> all = Collections.list(NetworkInterface.getNetworkInterfaces());
        for (NetworkInterface nif: all) {
            if (!nif.getName().equalsIgnoreCase("wlan0")) continue;

            byte[] macBytes = nif.getHardwareAddress();
            if (macBytes == null) {
                return "";
            }

            StringBuilder res1 = new StringBuilder();
            for (byte b: macBytes) {
                //res1.append(Integer.toHexString(b & 0xFF) + ":");
                res1.append(String.format("%02X:", b));
            }

            if (res1.length() > 0) {
                res1.deleteCharAt(res1.length() - 1);
            }
            return res1.toString();
        }
    } catch (Exception ex) {}
    return "02:00:00:00:00:00";
}

EDIT 1. This answer got a bug where a byte that in hex form got a single digit, will not appear with a "0" before it. The append to res1 has been changed to take care of it.

It's Working

    package com.keshav.fetchmacaddress;
    
    import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.util.Log;
    
    import java.net.InetAddress;
    import java.net.NetworkInterface;
    import java.net.SocketException;
    import java.net.UnknownHostException;
    import java.util.Collections;
    import java.util.List;
    
    public class MainActivity extends AppCompatActivity {
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
    
            Log.e("keshav","getMacAddr -> " +getMacAddr());
        }
    
        public static String getMacAddr() {
            try {
                List<NetworkInterface> all = Collections.list(NetworkInterface.getNetworkInterfaces());
                for (NetworkInterface nif : all) {
                    if (!nif.getName().equalsIgnoreCase("wlan0")) continue;
    
                    byte[] macBytes = nif.getHardwareAddress();
                    if (macBytes == null) {
                        return "";
                    }
    
                    StringBuilder res1 = new StringBuilder();
                    for (byte b : macBytes) {
                        // res1.append(Integer.toHexString(b & 0xFF) + ":");
                        res1.append(String.format("%02X:",b)); 
                    }
    
                    if (res1.length() > 0) {
                        res1.deleteCharAt(res1.length() - 1);
                    }
                    return res1.toString();
                }
            } catch (Exception ex) {
                //handle exception
            }
            return "";
        }
    }

UPDATE 1

This answer got a bug where a byte that in hex form got a single digit, will not appear with a "0" before it. The append to res1 has been changed to take care of it.

 StringBuilder res1 = new StringBuilder();
                for (byte b : macBytes) {
                    // res1.append(Integer.toHexString(b & 0xFF) + ":");
                    res1.append(String.format("%02X:",b)); 
                }

Here the Kotlin version of Arth Tilvas answer:

fun getMacAddr(): String {
    try {
        val all = Collections.list(NetworkInterface.getNetworkInterfaces())
        for (nif in all) {
            if (!nif.getName().equals("wlan0", ignoreCase=true)) continue

            val macBytes = nif.getHardwareAddress() ?: return ""

            val res1 = StringBuilder()
            for (b in macBytes) {
                //res1.append(Integer.toHexString(b & 0xFF) + ":");
                res1.append(String.format("%02X:", b))
            }

            if (res1.length > 0) {
                res1.deleteCharAt(res1.length - 1)
            }
            return res1.toString()
        }
    } catch (ex: Exception) {
    }

    return "02:00:00:00:00:00"
}