complete code casting exception on arrayadapter add

package com.voice.benz.instaremote;

import android.app.ListActivity;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.TextView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothClass;
import android.content.BroadcastReceiver;

import java.util.Set;

import android.content.Intent;
import android.content.Context;

import java.lang.reflect.Array;


public class MainActivity extends ActionBarActivity {

    private TextView txt_status;
    public ListView listView_newDevices, listView_pairedDevices;
    public ArrayAdapter<String> newDevicesAdapter;
    public ArrayAdapter<String> pairedDevicesAdapter;
    private Set<BluetoothDevice> pairedDevices;

    private BluetoothAdapter btAdapter;


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

        // Inizializza widgets
        txt_status = (TextView) findViewById(R.id.txt_status);
        listView_newDevices = (ListView) findViewById(R.id.listView_newDevices);
        listView_pairedDevices = (ListView) findViewById(R.id.listView_pairedDevices);

        // Inizializzazione Adapter

        ArrayAdapter<String> newDevicesAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1);
        ArrayAdapter<String> pairedDevicesAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1);

        // Assegna Adapters

        listView_newDevices.setAdapter(newDevicesAdapter);
        listView_pairedDevices.setAdapter(pairedDevicesAdapter);

        // Inizializza bluetooth adapter

        btAdapter = BluetoothAdapter.getDefaultAdapter();



    }

    // BROADCAST RECEIVER ------ GESTISCE CONNESSIONE

    private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();

            // When discovery finds a device
            if (BluetoothDevice.ACTION_FOUND.equals(action)) {
                //BluetoothDevice device = (BluetoothDevice) intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);

                //do something
            }

            else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) {
                //do something else
            }
        }
    };

    public void find_BondedDevices (View view) {

        // Cerca bonded devices SET
        pairedDevices = btAdapter.getBondedDevices();

        if (pairedDevices.size() > 0) {
            for (BluetoothDevice device : pairedDevices) {
                String deviceBTName = device.getName();
                String deviceBTMajorClass = getBTMajorDeviceClass(device
                        .getBluetoothClass()
                        .getMajorDeviceClass());
                pairedDevicesAdapter.add(deviceBTName + "\n" + deviceBTMajorClass);
            }
        }



    }

    private String getBTMajorDeviceClass(int major) {
        switch (major) {
            case BluetoothClass.Device.Major.AUDIO_VIDEO:
                return "AUDIO_VIDEO";
            case BluetoothClass.Device.Major.COMPUTER:
                return "COMPUTER";
            case BluetoothClass.Device.Major.HEALTH:
                return "HEALTH";
            case BluetoothClass.Device.Major.IMAGING:
                return "IMAGING";
            case BluetoothClass.Device.Major.MISC:
                return "MISC";
            case BluetoothClass.Device.Major.NETWORKING:
                return "NETWORKING";
            case BluetoothClass.Device.Major.PERIPHERAL:
                return "PERIPHERAL";
            case BluetoothClass.Device.Major.PHONE:
                return "PHONE";
            case BluetoothClass.Device.Major.TOY:
                return "TOY";
            case BluetoothClass.Device.Major.UNCATEGORIZED:
                return "UNCATEGORIZED";
            case BluetoothClass.Device.Major.WEARABLE:
                return "AUDIO_VIDEO";
            default:
                return "unknown!";
        }
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}