Good morning.
I am developing an app in android studio, in which I connect via bluetooth to the printer.
The detail is that if I leave the app the bluetooth connection to the printer is lost, and what I want is when I start the app I will automatically connect to the printer, I'll leave the code for what I am trying to do but the app thunders
This file is used so that from the bluetooth connection to the printer, that if it works for me because it is the use in my configuration screen.
public class ConexionBluetooth extends Activity {
private static final String TAG = "BluetoothConnectMenu";
// Intent request codes
// private static final int REQUEST_CONNECT_DEVICE = 1;
private static final int REQUEST_ENABLE_BT = 2;
ArrayAdapter<String> adapter;
private BluetoothAdapter mBluetoothAdapter;
private Vector<BluetoothDevice> remoteDevices;
private BroadcastReceiver searchFinish;
private BroadcastReceiver searchStart;
private BroadcastReceiver discoveryResult;
private Thread hThread;
private Context context;
private String MacAddres = "";
private BroadcastReceiver reconectar;
// UI
private EditText btAddrBox;
private Button connectButton;
private Button searchButton;
private ListView list;
// BT
private BluetoothPort bluetoothPort;
// Activar Bluetooth en caso de no estar activado
public void bluetoothSetup()
{
// Initialize
clearBtDevData();
bluetoothPort = BluetoothPort.getInstance();
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if (mBluetoothAdapter == null)
{
// Device does not support Bluetooth
return;
}
if (!mBluetoothAdapter.isEnabled())
{
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
}
}
private static final String dir = Environment.getExternalStorageDirectory().getAbsolutePath() + "//temp";
private static final String fileName = dir + "//BTPrinter";
private String lastConnAddr;
private void loadSettingFile()
{
int rin = 0;
char [] buf = new char[128];
try
{
FileReader fReader = new FileReader(fileName);
rin = fReader.read(buf);
if(rin > 0)
{
lastConnAddr = new String(buf,0,rin);
btAddrBox.setText(lastConnAddr);
}
fReader.close();
}
catch (FileNotFoundException e)
{
Log.i(TAG, "No existe historia de conexiones.");
}
catch (IOException e)
{
Log.e(TAG, e.getMessage(), e);
}
}
private void saveSettingFile()
{
try
{
File tempDir = new File(dir);
if(!tempDir.exists())
{
tempDir.mkdir();
}
FileWriter fWriter = new FileWriter(fileName);
if(lastConnAddr != null)
fWriter.write(lastConnAddr);
fWriter.close();
}
catch (FileNotFoundException e)
{
Log.e(TAG, e.getMessage(), e);
}
catch (IOException e)
{
Log.e(TAG, e.getMessage(), e);
}
}
// Limpiar lista de dispositivos.
private void clearBtDevData()
{
remoteDevices = new Vector<BluetoothDevice>();
}
// add paired device to list
private void addPairedDevices()
{
BluetoothDevice pairedDevice;
Iterator<BluetoothDevice> iter = (mBluetoothAdapter.getBondedDevices()).iterator();
while(iter.hasNext())
{
pairedDevice = iter.next();
remoteDevices.add(pairedDevice);
adapter.add(pairedDevice.getName() +"\n["+pairedDevice.getAddress()+"] [Paired]");
}
}
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.bluetooth_menu);
// Setting
btAddrBox = (EditText) findViewById(R.id.EditTextAddressBT);
connectButton = (Button) findViewById(R.id.ButtonConnectBT);
searchButton = (Button) findViewById(R.id.ButtonSearchBT);
list = (ListView) findViewById(R.id.ListView01);
context = this;
// Setting
loadSettingFile();
bluetoothSetup();
// Connect, Disconnect -- Button
connectButton.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
if(!bluetoothPort.isConnected()) // Connect routine.
{
try
{
Conectar(btAddrBox.getText().toString());
//btConn(mBluetoothAdapter.getRemoteDevice(btAddrBox.getText().toString()));
}
catch(IllegalArgumentException e)
{
// Bluetooth Address Format [OO:OO:OO:OO:OO:OO]
Log.e(TAG,e.getMessage(),e);
//AlertView.showAlert(e.getMessage(), context);
Toast.makeText(getApplicationContext(),e.getMessage(),Toast.LENGTH_LONG).show();
return;
}
}
else // Disconnect routine.
{
// Always run.
btDisconn();
}
}
});
// Search Button
searchButton.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
if (!mBluetoothAdapter.isDiscovering())
{
clearBtDevData();
adapter.clear();
mBluetoothAdapter.startDiscovery();
}
else
{
mBluetoothAdapter.cancelDiscovery();
}
}
});
// Bluetooth Device List
adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1);
list.setAdapter(adapter);
addPairedDevices();
// Connect - click the List item.
list.setOnItemClickListener(new AdapterView.OnItemClickListener()
{
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3)
{
BluetoothDevice btDev = remoteDevices.elementAt(arg2);
String Mac = String.valueOf(remoteDevices.elementAt(arg2));
if(mBluetoothAdapter.isDiscovering())
{
mBluetoothAdapter.cancelDiscovery();
}
btAddrBox.setText(btDev.getAddress());
//btConn(btDev);
Conectar(Mac);
}
});
// UI - Event Handler.
// Search device, then add List.
discoveryResult = new BroadcastReceiver()
{
@Override
public void onReceive(Context context, Intent intent)
{
String key;
BluetoothDevice remoteDevice = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
if(remoteDevice != null)
{
if(remoteDevice.getBondState() != BluetoothDevice.BOND_BONDED)
{
key = remoteDevice.getName() +"\n["+remoteDevice.getAddress()+"]";
}
else
{
key = remoteDevice.getName() +"\n["+remoteDevice.getAddress()+"] [Paired]";
}
remoteDevices.add(remoteDevice);
adapter.add(key);
}
}
};
registerReceiver(discoveryResult, new IntentFilter(BluetoothDevice.ACTION_FOUND));
searchStart = new BroadcastReceiver()
{
@Override
public void onReceive(Context context, Intent intent)
{
connectButton.setEnabled(false);
btAddrBox.setEnabled(false);
searchButton.setText(getResources().getString(R.string.bt_stop_search_btn));
}
};
registerReceiver(searchStart, new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_STARTED));
searchFinish = new BroadcastReceiver()
{
@Override
public void onReceive(Context context, Intent intent)
{
connectButton.setEnabled(true);
btAddrBox.setEnabled(true);
searchButton.setText(getResources().getString(R.string.bt_search_btn));
}
};
registerReceiver(searchFinish, new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_FINISHED));
}
//Funcion Para Conectar solo Mac en String
private void Conectar(final String MacAddres)
{
AsyncBluetooth task = new AsyncBluetooth();
task.execute(MacAddres);
}
// Bluetooth Metodo Desconectar.
public void btDisconn()
{
try
{
bluetoothPort.disconnect();
}
catch (Exception e)
{
Log.e(TAG, e.getMessage(), e);
}
if((hThread != null) && (hThread.isAlive()))
hThread.interrupt();
// UI
connectButton.setText(getResources().getString(R.string.dev_conn_btn));
list.setEnabled(true);
btAddrBox.setEnabled(true);
searchButton.setEnabled(true);
Toast.makeText(context, getResources().getString(R.string.bt_disconn_msg), Toast.LENGTH_SHORT).show();
}
//ClaSE Nueva de Asyntask ConexionBluetooth
public class AsyncBluetooth extends AsyncTask<String, Void,Integer>
{
private final ProgressDialog dialog = new ProgressDialog(ConexionBluetooth.this);
@Override
protected void onPreExecute() {
dialog.setTitle(getResources().getString(R.string.bt_tab));
dialog.setMessage(getResources().getString(R.string.connecting_msg));
dialog.show();
super.onPreExecute();
}
@Override
protected Integer doInBackground(String... params) {
Integer resultado = null;
try
{
SharedPreferences bluetooth = getSharedPreferences("ConexionBluetooth",0);
SharedPreferences.Editor editor = bluetooth.edit();
editor.putString("Mac",params[0]);
editor.commit();
lastConnAddr = params[0];
bluetoothPort.connect(lastConnAddr);
resultado = Integer.valueOf(0);
}catch (IOException e)
{
resultado = Integer.valueOf(-1);
}
return resultado;
}
@Override
protected void onPostExecute(Integer result) {
if (result.intValue() == 0)
{
RequestHandler rh = new RequestHandler();
hThread = new Thread(rh);
hThread.start();
// UI
connectButton.setText(getResources().getString(R.string.dev_disconn_btn));
list.setEnabled(false);
btAddrBox.setEnabled(false);
searchButton.setEnabled(false);
if(dialog.isShowing())
dialog.dismiss();
Toast.makeText(context, getResources().getString(R.string.bt_conn_msg), Toast.LENGTH_SHORT).show();
}else
{
if(dialog.isShowing())
dialog.dismiss();
AlertView.showAlert(getResources().getString(R.string.bt_conn_fail_msg),
getResources().getString(R.string.dev_check_msg), context);
}
super.onPostExecute(result);
}
}
}
And what I'm doing is that on my login screen, there's a call again to call my Asynctask for the connection, it thunders to me
SharedPreferences bluetooth = getSharedPreferences("ConexionBluetooth",0);
AsyncBluetooth tas2 = new AsyncBluetooth();
tas2.execute(bluetooth.getString("Mac",""));
public class AsyncBluetooth extends AsyncTask<String, Void,Integer>
{
private final ProgressDialog dialog = new ProgressDialog(Login.this);
@Override
protected void onPreExecute() {
dialog.setTitle(getResources().getString(R.string.bt_tab));
dialog.setMessage(getResources().getString(R.string.connecting_msg));
dialog.show();
super.onPreExecute();
}
@Override
protected Integer doInBackground(String... params) {
Integer resultado = null;
try
{
lastConnAddr = params[0];
bluetoothPort.connect(params[0]);
resultado = Integer.valueOf(0);
}catch (IOException e)
{
resultado = Integer.valueOf(-1);
}
return resultado;
}
@Override
protected void onPostExecute(Integer result) {
if (result.intValue() == 0)
{
RequestHandler rh = new RequestHandler();
hThread = new Thread(rh);
hThread.start();
// UI
if(dialog.isShowing())
dialog.dismiss();
Toast.makeText(context, getResources().getString(R.string.bt_conn_msg), Toast.LENGTH_SHORT).show();
}else
{
if(dialog.isShowing())
dialog.dismiss();
AlertView.showAlert(getResources().getString(R.string.bt_conn_fail_msg),
getResources().getString(R.string.dev_check_msg), context);
}
super.onPostExecute(result);
}
Error, I told you that the Asynctask call was made on Oncreate, I do not know if it's ok.
E / AndroidRuntime: FATAL EXCEPTION: AsyncTask # 2 Process: mx.com.oncontrol.oncontroldesconnected, PID: 5021 java.lang.RuntimeException: An error occured while executing doInBackground () at android.os.AsyncTask $ 3.done (AsyncTask.java:300) at java.util.concurrent.FutureTask.finishCompletion (FutureTask.java:355) at java.util.concurrent.FutureTask.setException (FutureTask.java:222) at java.util.concurrent.FutureTask.run (FutureTask.java:242) at android.os.AsyncTask $ SerialExecutor $ 1.run (AsyncTask.java:231) at java.util.concurrent.ThreadPoolExecutor.runWorker (ThreadPoolExecutor.java:1112) at java.util.concurrent.ThreadPoolExecutor $ Worker.run (ThreadPoolExecutor.java:587) at java.lang.Thread.run (Thread.java:831) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.citizen.port.android.BluetoothPort.connect (java.lang.String) 'on a null object reference at mx.com.oncontrol.oncontroldesconnected.Login $ AsyncBluetooth.doInBackground (Login.java:506) at mx.com.oncontrol.oncontroldesconnected.Login $ AsyncBluetooth.doInBackground (Login.java:485) at android.os.AsyncTask $ 2.call (AsyncTask.java:288) at java.util.concurrent.FutureTask.run (FutureTask.java:237) at android.os.AsyncTask $ SerialExecutor $ 1.run (AsyncTask.java:231) at java.util.concurrent.ThreadPoolExecutor.runWorker (ThreadPoolExecutor.java:1112) at java.util.concurrent.ThreadPoolExecutor $ Worker.run (ThreadPoolExecutor.java:587) at java.lang.Thread.run (Thread.java:831)
bluetooth port function that I use to connect to the printer
public void connect(String address) throws IOException {
BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
BluetoothDevice bluetoothDevice = mBluetoothAdapter.getRemoteDevice(address);
if(mBluetoothAdapter.isDiscovering()) {
mBluetoothAdapter.cancelDiscovery();
}
if(!this.isValidAddress(address)) {
throw new IOException("Bluetooth Address is not valid.");
} else {
this.setBTSocket(bluetoothDevice);
this.connectCommon();
}
}