Blog

package com.programmerworld.myapplication;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.TextView;

import java.net.NetworkInterface;
import java.net.SocketException;
import java.util.Collections;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private TextView textView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        textView = findViewById(R.id.textView);
    }

    public void buttonClick(View view){

        try {
            List<NetworkInterface> networkInterfaceList = Collections.list(NetworkInterface.getNetworkInterfaces());

            String stringMac = "";

            for (NetworkInterface networkInterface:networkInterfaceList){
                if (networkInterface.getName().equalsIgnoreCase("wlan0")){
                    for (int i=0; i<networkInterface.getHardwareAddress().length;i++){
                        String stringMacByte = Integer.toHexString(networkInterface.getHardwareAddress()[i] & 0xFF);

                        if (stringMacByte.length() == 1){
                            stringMacByte = "0" + stringMacByte;
                        }

                        stringMac = stringMac + stringMacByte.toUpperCase() + ":";
                    }
                    break;
                }
            }

            textView.setText(stringMac.substring(0,stringMac.length()-1));


        } catch (SocketException e) {
            e.printStackTrace();
        }
    }
}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.programmerworld.myapplication">

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

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        android:textSize="30sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="107dp"
        android:layout_marginTop="101dp"
        android:onClick="buttonClick"
        android:text="@string/get_mac_address"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>