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I’m making an application to send some characters by Bluetooth to an Arduino, however, I can not save the mac address of the module used. The mistake happens right here:
EXTRA_ADDRESS = date.getExtras(). getString(MAC_ADRESS);
MainActivity
package aluno.fabio.projetofresadora;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Toast;
import java.io.IOException;
import java.util.Set;
import java.util.UUID;
import static aluno.fabio.projetofresadora.ListaDispositivos.MAC_ADRESS;
public class MainActivity extends AppCompatActivity {
private BluetoothAdapter myBluetooth = null;
private Set<BluetoothDevice> pairedDevices;
public static String EXTRA_ADDRESS = null;
private static final int REQUEST_CODE=1;
Set<BluetoothDevice> paired_devices;
String lists[];
boolean conexao = false;
private static final int REQUEST_CONEXAO = 2;
BluetoothDevice myDevice = null;
BluetoothSocket mySocket = null;
Button btnPaired;
ListView devicelist;
ConnectedThread Conectarei;
private static String OMAC_ADRESS = null;
UUID MY_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button Movimentos = (Button) findViewById(R.id.movimentabotao);
Button Sobre = (Button) findViewById(R.id.sobrebotao);
Button Manual = (Button) findViewById(R.id.manualbotao);
btnPaired = (Button) findViewById(R.id.conexao);
devicelist = (ListView)findViewById(R.id.listView);
myBluetooth = BluetoothAdapter.getDefaultAdapter();
if(myBluetooth == null)
{
Toast.makeText(getApplicationContext(), "Bluetooth Não Disponínel", Toast.LENGTH_LONG).show();
finish();
}
else if(!myBluetooth.isEnabled())
{
Intent turnBTon = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(turnBTon,1);
}
Movimentos.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Intent it = new Intent(MainActivity.this, Movimentos.class);
startActivity(it);
}
});
Sobre.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Intent it = new Intent(MainActivity.this, Sobre.class);
startActivity(it);
}
});
Manual.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Intent it = new Intent(MainActivity.this, manual.class);
startActivity(it);
}
});
btnPaired.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(conexao){
//desconectar
try{
mySocket.close();
conexao = false;
Toast.makeText(getApplicationContext(), "Conexão finalizada", Toast.LENGTH_LONG).show();
btnPaired.setText("Conectar");
}catch(IOException erro){
Toast.makeText(getApplicationContext(), "Ocorreu um erro " + erro, Toast.LENGTH_LONG).show();
}
}else{
//conectar
Intent abreLista = new Intent(MainActivity.this, ListaDispositivos.class);
startActivityForResult(abreLista, REQUEST_CONEXAO);
}
}
});
}
public void onActivityResult(int requestcode, int resultcode, Intent data){
switch (requestcode){
case REQUEST_CODE:
if (resultcode == Activity.RESULT_OK){
Toast.makeText(getApplicationContext(), "Bluetooth Ativado", Toast.LENGTH_LONG).show();
}else {
Toast.makeText(getApplicationContext(), "Bluetooth Não Ativado", Toast.LENGTH_LONG).show();
finish();
}
break;
case REQUEST_CONEXAO:
if(resultcode == Activity.RESULT_OK){
EXTRA_ADDRESS = data.getExtras().getString(MAC_ADRESS);
myDevice = myBluetooth.getRemoteDevice(EXTRA_ADDRESS);
try{
mySocket = myDevice.createRfcommSocketToServiceRecord(MY_UUID);
mySocket.connect();
conexao = true;
Conectarei = new ConnectedThread(mySocket);
Conectarei.start();
btnPaired.setText("Desconectar");
Toast.makeText(getApplicationContext(), "Conectado no Dispositivo " + MAC_ADRESS, Toast.LENGTH_LONG).show();
}catch (IOException erro) {
Toast.makeText(getApplicationContext(),"Ocorreu um erro" + erro, Toast.LENGTH_LONG).show();
conexao = false;
}
}else{
Toast.makeText(getApplicationContext(), "Falha ao obter MAC ADRESS", Toast.LENGTH_LONG).show();
}
}
}
}
Connectionthread
package aluno.fabio.projetofresadora;
import android.bluetooth.BluetoothSocket;
import java.io.IOException;
import java.io.OutputStream;
class ConnectedThread extends Thread {
private final BluetoothSocket mmSocket;
private final OutputStream mmOutStream;
public ConnectedThread(BluetoothSocket socket) {
mmSocket = socket;
OutputStream tmpOut = null;
try {
tmpOut = socket.getOutputStream();
} catch (IOException e) { }
mmOutStream = tmpOut;
}
public void write(String enviadados) {
byte[] msgbuffer = enviadados.getBytes();
try {
mmOutStream.write(msgbuffer);
} catch (IOException e) { }
}
}
Listdevices
package aluno.fabio.projetofresadora;
import android.app.ListActivity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import java.util.Set;
public class ListaDispositivos extends ListActivity {
private BluetoothAdapter myBluetoothAdapter = null;
static String MAC_ADRESS = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ArrayAdapter<String> ArrayBluetooth = new ArrayAdapter <String> (this,android.R.layout.simple_list_item_1);
myBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
Set<BluetoothDevice> pairedDevices = myBluetoothAdapter.getBondedDevices();
if (pairedDevices.size()>0)
{
for(BluetoothDevice bt : pairedDevices)
{
String nomebt = bt.getName();
String macadressdev = bt.getAddress();
ArrayBluetooth.add(nomebt + "\n" + macadressdev);
}
}
else
{
Toast.makeText(getApplicationContext(), "Sem Dispositivos Pareados", Toast.LENGTH_LONG).show();
}
setListAdapter(ArrayBluetooth);
}
@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
super.onListItemClick(l, v, position, id);
String infoall = ((TextView) v).getText().toString();
String onlymac = infoall.substring(infoall.length() - 17);
Intent rt = new Intent();
rt.putExtra(MAC_ADRESS, onlymac);
setResult(RESULT_OK, rt);
finish();
}
}
What is Nullpointerexception and what are its main causes?
– NoobSaibot
Or the
data
is void, or thedata.getExtras()
returns null. Most likely you are forgetting to send Intent.– Max Fratane