title: What can I do by getBluetoothService() called with no BluetoothManagerCallback ?
body: <p>hi I want to write a Android java application that can connect with a bluetooth device but I get the error: </p>
  
  <pre><code>W/BluetoothAdapter﹕ getBluetoothService() called with no BluetoothManagerCallback
  </code></pre>
  
  <p>I use a Nexus 5 device with android version 4.4.4 </p>
  
  <p>here is my code: </p>
  
  <pre><code>package com.example.tarasov.bluetoothexample;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.util.ArrayList;
  import java.util.Set;
  import java.util.UUID;
  import android.view.Menu;
  import android.view.MenuItem;
  import android.app.Activity;
  import android.bluetooth.BluetoothAdapter;
  import android.bluetooth.BluetoothDevice;
  import android.bluetooth.BluetoothSocket;
  import android.content.BroadcastReceiver;
  import android.content.Context;
  import android.content.Intent;
  import android.content.IntentFilter;
  import android.os.Bundle;
  import android.os.Handler;
  import android.os.Message;
  import android.util.Log;
  import android.view.View;
  import android.widget.AdapterView;
  import android.widget.AdapterView.OnItemClickListener;
  import android.widget.ArrayAdapter;
  import android.widget.ListView;
  import android.widget.Toast;
  
  
  public class MyActivity extends Activity implements OnItemClickListener {
  
      /*
      * Deklaration
      * */
  
      ArrayAdapter&lt;String&gt; listAdapter;
      ListView listView;
      BluetoothAdapter btAdapter;
      Set&lt;BluetoothDevice&gt; deviceArray;
      ArrayList&lt;String&gt; pairedDevices;
      ArrayList&lt;BluetoothDevice&gt; devices;
      public static final UUID MY_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
      protected static final int SUCCESS_CONNECT = 0;
      protected static final int MESSAGE_READ = 1;
      IntentFilter filter;
      BroadcastReceiver receiver;
      String tag = "debugging";
      Handler mHandler = new Handler(){
          @Override
          public void handleMessage(Message msg) {
              // TODO Auto-generated method stub
              Log.i(tag, "in handler");
              super.handleMessage(msg);
              switch(msg.what){
                  case SUCCESS_CONNECT:
                      // DO something
                      ConnectedThread connectedThread = new ConnectedThread((BluetoothSocket)msg.obj);
                      Toast.makeText(getApplicationContext(), "CONNECT", Toast.LENGTH_SHORT).show();
                      String s = "successfully connected";
                      connectedThread.write(s.getBytes());
                      Log.i(tag, "connected");
                      break;
                  case MESSAGE_READ:
                      byte[] readBuf = (byte[])msg.obj;
                      String string = new String(readBuf);
                      Toast.makeText(getApplicationContext(), string, Toast.LENGTH_SHORT).show();
                      break;
              }
          }
      };
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_my);
  
          init(); //Initialisierung der Komponenten
  
          if(btAdapter==null)
          {
              Toast.makeText(getApplicationContext(), "Kein Bluetooth aktiviert", Toast.LENGTH_SHORT).show();
              finish();
          }
          else
          {
              if (!btAdapter.isEnabled()){
  
                  turnOnBT();
              }
  
              getPairedDevices();
              startDiscovery();
          }
  
      }
  
      private void startDiscovery() {
          btAdapter.cancelDiscovery();
          btAdapter.startDiscovery();
      }
  
      private void turnOnBT() {
          Intent intent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
          startActivityForResult(intent,1);
      }
  
      private void getPairedDevices() {
  
          deviceArray = btAdapter.getBondedDevices();
          if (deviceArray.size()&gt;0){
              for (BluetoothDevice device:deviceArray){
                  pairedDevices.add(device.getName());
  
              }
          }
      }
  
      private void init(){
  
          listView = (ListView)findViewById(R.id.listView); //bindet ListView
          listView.setOnItemClickListener(this);
          listAdapter = new ArrayAdapter&lt;String&gt;(this,android.R.layout.simple_list_item_1,0);
          listView.setAdapter(listAdapter);
          btAdapter = BluetoothAdapter.getDefaultAdapter();
          pairedDevices = new ArrayList&lt;String&gt;();
          filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
          devices = new ArrayList&lt;BluetoothDevice&gt;();
          receiver = new BroadcastReceiver() {
              @Override
              public void onReceive(Context context, Intent intent) {
                  String action = intent.getAction();
  
                  if (BluetoothDevice.ACTION_FOUND.equals(action)){
                      BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
                      devices.add(device);
                      String s = "";
  
                      for (int a=0;a&lt; pairedDevices.size();a++){
                          if (device.getName().equals(pairedDevices.get(a))){
  
                              s = "(Verbunden)";
                              break;
                          }
                      }
  
                      listAdapter.add(device.getName()+" "+s+" "+"\n"+device.getAddress());
                  }
  
                  else if (BluetoothAdapter.ACTION_DISCOVERY_STARTED.equals(action)){
  
                  }
                  else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)){
  
  
                  }
                  else if (BluetoothAdapter.ACTION_STATE_CHANGED.equals(action)){
                      if (btAdapter.getState()==btAdapter.STATE_OFF){
                          turnOnBT();
                      }
                  }
              }
          };
  
          registerReceiver(receiver,filter);
          filter = new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_STARTED);
  
          registerReceiver(receiver,filter);
          filter = new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
  
          registerReceiver(receiver,filter);
          filter = new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED);
  
          registerReceiver(receiver,filter);
      }
  
      @Override
      protected void onPause() {
          super.onPause();
  
          unregisterReceiver(receiver);
      }
  
      @Override
      protected void onActivityResult(int requestCode, int resultCode, Intent data) {
          super.onActivityResult(requestCode, resultCode, data);
  
          if (resultCode==RESULT_CANCELED){
  
              Toast.makeText(getApplicationContext(), "Bluetooth muss erst aktiviert werden", Toast.LENGTH_SHORT).show();
              finish();
          }
      }
  
      @Override
      public void onItemClick(AdapterView&lt;?&gt; arg0, View arg1, int arg2, long arg3) {
  
          if (btAdapter.isDiscovering()){
              btAdapter.cancelDiscovery();
          }
  
          if (listAdapter.getItem(arg2).contains("Verbunden")){
  
              BluetoothDevice selectedDevice = devices.get(arg2);
              ConnectThread connect = new ConnectThread(selectedDevice);
              connect.start();
              Log.i(tag, "in click listener");
          }
          else
          {
              Toast.makeText(getApplicationContext(), "Gerät ist nicht verbunden", Toast.LENGTH_SHORT).show();
          }
      }
  
      /*
      * Hilfsklassen
      * */
  
      private class ConnectThread extends Thread {
  
          private final BluetoothSocket mmSocket;
          private final BluetoothDevice mmDevice;
  
          public ConnectThread(BluetoothDevice device) {
              // Use a temporary object that is later assigned to mmSocket,
              // because mmSocket is final
              BluetoothSocket tmp = null;
              mmDevice = device;
              Log.i(tag, "construct");
              // Get a BluetoothSocket to connect with the given BluetoothDevice
              try {
                  // MY_UUID is the app's UUID string, also used by the server code
                  tmp = device.createRfcommSocketToServiceRecord(MY_UUID);
              } catch (IOException e) {
                  Log.i(tag, "get socket failed");
  
              }
              mmSocket = tmp;
          }
  
          public void run() {
              // Cancel discovery because it will slow down the connection
              btAdapter.cancelDiscovery();
              Log.i(tag, "connect - run");
              try {
                  // Connect the device through the socket. This will block
                  // until it succeeds or throws an exception
                  mmSocket.connect();
                  Log.i(tag, "connect - succeeded");
              } catch (IOException connectException) {    Log.i(tag, "connect failed");
                  // Unable to connect; close the socket and get out
                  try {
                      mmSocket.close();
                  } catch (IOException closeException) { }
                  return;
              }
  
              // Do work to manage the connection (in a separate thread)
  
              mHandler.obtainMessage(SUCCESS_CONNECT, mmSocket).sendToTarget();
          }
  
          /** Will cancel an in-progress connection, and close the socket */
          public void cancel() {
              try {
                  mmSocket.close();
              } catch (IOException e) { }
          }
      }
  
      private class ConnectedThread extends Thread {
          private final BluetoothSocket mmSocket;
          private final InputStream mmInStream;
          private final OutputStream mmOutStream;
  
          public ConnectedThread(BluetoothSocket socket) {
              mmSocket = socket;
              InputStream tmpIn = null;
              OutputStream tmpOut = null;
  
              // Get the input and output streams, using temp objects because
              // member streams are final
              try {
                  tmpIn = socket.getInputStream();
                  tmpOut = socket.getOutputStream();
              } catch (IOException e) { }
  
              mmInStream = tmpIn;
              mmOutStream = tmpOut;
          }
  
          public void run() {
              byte[] buffer;  // buffer store for the stream
              int bytes; // bytes returned from read()
  
              // Keep listening to the InputStream until an exception occurs
              while (true) {
                  try {
                      // Read from the InputStream
                      buffer = new byte[1024];
                      bytes = mmInStream.read(buffer);
                      // Send the obtained bytes to the UI activity
                      mHandler.obtainMessage(MESSAGE_READ, bytes, -1, buffer)
                              .sendToTarget();
  
                  } catch (IOException e) {
                      break;
                  }
              }
          }
  
          /* Call this from the main activity to send data to the remote device */
          public void write(byte[] bytes) {
              try {
                  mmOutStream.write(bytes);
              } catch (IOException e) { }
          }
  
          /* Call this from the main activity to shutdown the connection */
          public void cancel() {
              try {
                  mmSocket.close();
              } catch (IOException e) { }
          }
      }
  </code></pre>