Using bluetooth on Android

package com.example.sairamkrishna.myapplication; import android.app.Activity; import android.bluetooth.BluetoothAdapter; import android.bluetooth.BluetoothDevice; import android.content.BroadcastReceiver; import android.content.Context; import android.content.Intent; import android.content.IntentFilter; import android.graphics.Color; import android.net.wifi.ScanResult; import android.net.wifi.WifiManager; import android.os.Bundle; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.widget.ArrayAdapter; import android.widget.Button; import android.widget.EditText; import android.widget.ListView; import android.widget.TextView; import android.widget.Toast; import java.util.ArrayList; import java.util.List; import java.util.Set; public class MainActivity extends Activity { Button b1,b2,b3,b4; private BluetoothAdapter BA; private Set<BluetoothDevice>pairedDevices; ListView lv; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); b1 = (Button) findViewById(R.id.button); b2=(Button)findViewById(R.id.button2); b3=(Button)findViewById(R.id.button3); b4=(Button)findViewById(R.id.button4); BA = BluetoothAdapter.getDefaultAdapter(); lv = (ListView)findViewById(R.id.listView); } public void on(View v){ if (!BA.isEnabled()) { Intent turnOn = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE); startActivityForResult(turnOn, 0); Toast.makeText(getApplicationContext(),"Turned on",Toast.LENGTH_LONG).show(); } else { Toast.makeText(getApplicationContext(),"Already on", Toast.LENGTH_LONG).show(); } } public void off(View v){ BA.disable(); Toast.makeText(getApplicationContext(),"Turned off" ,Toast.LENGTH_LONG).show(); } public void visible(View v){ Intent getVisible = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE); startActivityForResult(getVisible, 0); } public void list(View v){ pairedDevices = BA.getBondedDevices(); ArrayList list = new ArrayList(); for(BluetoothDevice bt : pairedDevices) list.add(bt.getName()); Toast.makeText(getApplicationContext(),"Showing Paired Devices",Toast.LENGTH_SHORT).show(); final ArrayAdapter adapter = new ArrayAdapter(this,android.R.layout.simple_list_item_1, list); lv.setAdapter(adapter); } @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); } }