I am making an application that searches and connects to bluetooth devices My problem is that when I change Activity and return to close the connection my BluetoothSocket returns to NULL and when I call the method for close() to close the connection no longer closes it.
I was studying the possibility of creating a service that runs in the background so that when changing Activity, the Socket is not set to NULL .
If I do not change Activity, the connection and disconnection are done normally.
private BluetoothSocket mBTSocket;
These are the Functions I use
private class ConnectThread extends Thread {
//private BluetoothSocket mmSocket;
private final BluetoothDevice mmDevice;
private final String mmAddress;
private final String mmName;
private final UUID mmUUID;
public ConnectThread(BluetoothDevice device,final String name, final String address,UUID uuid,Handler handler) {
this.mmAddress = address;
this.mmName = name;
this.mmDevice = device;
//this.mmSocket = socket;
this.mmUUID = uuid;
BluetoothSocket tmp = null;
try {
tmp = mmDevice.createRfcommSocketToServiceRecord(mmUUID);
} catch (IOException e) {
e.printStackTrace();
}
//mmSocket = tmp;
mBTSocket = tmp;
}
@Override
public void run() {
boolean connected = false;
mBluetoothAdapter.cancelDiscovery();
try {
mBTSocket.connect();
connected = true;
} catch(IOException e) {
Log.d("CONNECTTHREAD","Could not connect: " + e.toString());
try {
//bTSocket.close();
mBTSocket.close();
handler.obtainMessage(STATE_CONNECTION_FAILED).sendToTarget();
connected = false;
} catch(IOException close) {
Log.d("CONNECTTHREAD", "Could not close connection:" + e.toString());
handler.obtainMessage(STATE_CONNECTION_FAILED).sendToTarget();
connected = false;
}
}
if(connected){
mConnectedThread = new ConnectedThread(mBTSocket);
mConnectedThread.start();
handler.obtainMessage(STATE_CONNECTED, mmName).sendToTarget();
handler.obtainMessage(STATE_CONNECTED_MAC,mmAddress).sendToTarget();
}
}
public void cancel() {
try {
mBTSocket.close();
//mBTSocket = null;
} catch (IOException e) {
handler.obtainMessage(STATE_DISCONNECTION_FAILED).sendToTarget();
}
}
}
This is the 2nd Function
private class ConnectedThread extends Thread{
private final BluetoothSocket mmSocket;
private final InputStream mmInStream;
private final OutputStream mmOutStream;
public ConnectedThread(BluetoothSocket socket){
mmSocket = socket;
InputStream tempIn = null;
OutputStream temOut = null;
try {
tempIn = mmSocket.getInputStream();
temOut = mmSocket.getOutputStream();
} catch (IOException e) {
e.printStackTrace();
}
mmInStream = tempIn;
mmOutStream = temOut;
}
public void run(){
byte[] buffer = new byte[1024];
int bytes;
while (true){
try {
bytes = mmInStream.available();
if(bytes != 0) {
}
} catch (IOException e) {
e.printStackTrace();
break;
}
}
}
public void write(String input) {
byte[] bytes = input.getBytes();
try {
mmOutStream.write(bytes);
} catch (IOException e) { }
}
public void cancel() {
try {
mmSocket.close();
handler.obtainMessage(STATE_DISCONNECT).sendToTarget();
} catch (IOException e) {
handler.obtainMessage(STATE_DISCONNECTION_FAILED).sendToTarget();
}
}
}
Messages at Handler I use to modify a TextView that shows the device with which the connection was established.
private final Handler handlerBT = new Handler(new Handler.Callback() {
@SuppressLint("SetTextI18n")
@Override
public boolean handleMessage(Message msg) {
switch (msg.what){
case STATE_SEARCHING:
((Button) findViewById(R.id.button_scan_id)).setText(R.string.cancelar);
textView_StatusBT_MAC.setText("");
textView_StatusBT.setText("Buscando ...handler");
break;
case STATE_NO_SEARCHING:
((Button) findViewById(R.id.button_scan_id)).setText(R.string.buscar);
break;
case STATE_CONNECTING:
textView_StatusBT.setText("Conectando... handler");
break;
case STATE_CONNECTED:
textView_StatusBT.setText("Conectado a: " + (String)(msg.obj));
break;
case STATE_CONNECTED_MAC:
textView_StatusBT_MAC.setText((String)(msg.obj));
break;
case STATE_DISCONNECT:
textView_StatusBT.setText("Desconetado...handler" );
textView_StatusBT_MAC.setText("");
break;
case STATE_DISCONNECTION_FAILED:
textView_StatusBT.setText("Fallo en Desconexion...handler" );
textView_StatusBT_MAC.setText("");
break;
case STATE_BT_ON:
((Button) findViewById(R.id.button_Conect_id)).setText(R.string.apagar_bluetooth);
textView_StatusBT.setText("Encendido...handler");
break;
case STATE_BT_OFF:
((Button) findViewById(R.id.button_Conect_id)).setText(R.string.encender_bluetooth);
textView_StatusBT.setText("Apagado...handler");
break;
case STATE_FOUND:
textView_StatusBT.setText("Dispositivos Encontrados ...handler");
break;
case STATE_NOT_FOUND:
textView_StatusBT.setText("No se encontraron Dispositivos ...handler");
break;
case STATE_TEST:
break;
case STATE_CONNECTION_FAILED:
textView_StatusBT.setText("Connection Failed...handler");
break;
case STATE_MESSAGE_RECEIVED:
//despues
break;
}
return true;
}
});