Retrieve IP and MAC addresses from /proc/net/arp

Last post "Display WiFi Hotspot clients by "cat /proc/net/arp"" display arp as human readable string, but not machine readable. It's another version to retrieve IP and MAC addresses, store in a ArrayList.

MainActivity.java

package com.blogspot.android_er.androidlistclient;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    Button btnRead;
    TextView textResult;

    ArrayList<Node> listNote;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btnRead = (Button)findViewById(R.id.readclient);
        textResult = (TextView)findViewById(R.id.result);

        listNote = new ArrayList<>();

        btnRead.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                readAddresses();
                textResult.setText("");
                for(int i=0; i<listNote.size(); i++){
                    textResult.append(i + " ");
                    textResult.append(listNote.get(i).toString());
                    textResult.append("\n");
                }
            }
        });
    }

    private void readAddresses() {
        listNote.clear();
        BufferedReader bufferedReader = null;

        try {
            bufferedReader = new BufferedReader(new FileReader("/proc/net/arp"));

            String line;
            while ((line = bufferedReader.readLine()) != null) {
                String[] splitted = line.split(" +");
                if (splitted != null && splitted.length >= 4) {
                    String ip = splitted[0];
                    String mac = splitted[3];
                    if (mac.matches("..:..:..:..:..:..")) {
                        Node thisNode = new Node(ip, mac);
                        listNote.add(thisNode);
                    }
                }
            }

        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally{
            try {
                bufferedReader.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    class Node {
        String ip;
        String mac;

        Node(String ip, String mac){
            this.ip = ip;
            this.mac = mac;
        }

        @Override
        public String toString() {
            return ip + " " + mac;
        }
    }
}

layout/activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="16dp"
    android:orientation="vertical"
    tools:context="com.blogspot.android_er.androidlistclient.MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:autoLink="web"
        android:text="http://android-er.blogspot.com/"
        android:textStyle="bold" />

    <Button
        android:id="@+id/readclient"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textAllCaps="false"
        android:text="Read Ip/MAC addresses"/>

    <TextView
        android:id="@+id/result"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:typeface="monospace"
        android:textSize="24sp"/>
</LinearLayout>

Next:
- Lookup manufacturer info by MAC address, using www.macvendorlookup.com API
- Get HostName of WiFi hotspot clients, and check if it is still connected