Please see this thread:
https://groups.google.com/forum/#!topic/android-developers/Buiu0XaUSQs
IOTW,
Change this:
runnable.run();
to this:
new Thread(runnable).start();
On Wednesday, January 16, 2013 10:05:19 AM UTC-6, Antonis Kanaris wrote:
>
>
>
> I created an application with bluetooth, but when bluetooth is closed i
> put enable request for open bt but apk crashing,close after show toast
> request for user and must restart the apk and I have this error... *
> java.lang.NullPointerException* in *io.webbt.Activity2.openBT.Any idea?I
> must use OnResume OnActivityResult?How i fix it?*
>
> * public class Activity2 extends Activity {
>
> public String strValue;
> public String strValue2;
> public String strUrlup;
>
> public String strValued ="http://";;
> public String strValue2d ="HC-07";
> public String strValue3d="";
>
> public String data="0";//Temperature (data from arduino)
>
> public boolean killMe = false;
>
> TextView temptext,txt,myLabel,text,text2,text3,text4;
>
> Handler handler = new Handler();
>
> BluetoothAdapter mBluetoothAdapter;
> BluetoothSocket mmSocket;
> BluetoothDevice mmDevice;
> OutputStream mmOutputStream;
> InputStream mmInputStream;
>
> Thread workerThread;
> byte[] readBuffer;
> int readBufferPosition;
> int counter;
> volatile boolean stopWorker;
> boolean work = true;
> private static final int REQUEST_ENABLE_BT = 1;
> public long refreshtime = 30000;//replay download/upload time 30 secs
>
> /** Called when the activity is first created. */
> public void onCreate(Bundle savedInstanceState) {
> super.onCreate(savedInstanceState);
> setContentView(R.layout.activity2);
>
> myLabel = (TextView)findViewById(R.id.label);
> temptext = (TextView)findViewById(R.id.temptxt);
>
> SharedPreferences preferences = getSharedPreferences("dataioweb" ,
> MODE_PRIVATE);
>
> strValue = preferences.getString("Url",strValued);
> text = (TextView) findViewById(R.id.txt1);
> text.setText(strValue);
> strValue2 = preferences.getString("DevName",strValue2d);
> text2 = (TextView) findViewById(R.id.txt2);
> text2.setText(strValue2);
> strUrlup = preferences.getString("Urlup",strValue3d);
> text4 = (TextView) findViewById(R.id.txt4);
> text4.setText(strUrlup);
>
> //findBT();
> }
>
> private class DownloadWebPageTask extends AsyncTask<String, Void,
> String> {
> @Override
> protected String doInBackground(String... urls) {
> String response = "";
> for (String url : urls) {
> DefaultHttpClient client = new DefaultHttpClient();
> HttpGet httpGet = new HttpGet(url);
> try {
> HttpResponse execute = client.execute(httpGet);
> InputStream content = execute.getEntity().getContent();
>
> BufferedReader buffer = new BufferedReader(new
> InputStreamReader(content));
> String s = "";
> while ((s = buffer.readLine()) != null) {
> response += s;
> }
>
> } catch (Exception e) {
> e.printStackTrace();
> }
> }
> return response;
> }
>
> @Override
> protected void onPostExecute(String result) {
> TextView text3 = (TextView) findViewById(R.id.txt3);
> text3.setText(result);
> try {
> sendData(result);
> } catch (IOException e) {
> // TODO Auto-generated catch block
> e.printStackTrace();
> }
>
> }
> }
>
>
>
> protected void onStart() {
> super.onStart();
>
> try
> {
> findBT();
> openBT();
> }
> catch (IOException ex) { }
>
> runnable.run();
>
> }
>
> protected void onResume() {
> super.onResume();
>
>
>
> }
>
> private Runnable runnable = new Runnable()
> {
>
> public void run()
> {
> if(killMe)
> return;
> DownloadWebPageTask task = new DownloadWebPageTask();
> task.execute(new String[] { strValue });//Download data
> on/off
>
> beginListenForData();//Listen Bluetooth temperature
>
> SimpleHttpPut task2 = new SimpleHttpPut();
> task2.execute(new String[] { strUrlup,data });//Upload
> data class
>
> handler.postDelayed(this, refreshtime);//Refresh page time
> }
> };
>
> void findBT()
> {
> mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
> if(mBluetoothAdapter == null)
> {
> myLabel.setText("No bluetooth adapter available");
> }
>
> if(!mBluetoothAdapter.isEnabled())
> {
>
> Intent enableBluetooth = new
> Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
> startActivityForResult(enableBluetooth, REQUEST_ENABLE_BT);
>
> //mBluetoothAdapter.enable();
>
>
> }
>
> Set<BluetoothDevice> pairedDevices =
> mBluetoothAdapter.getBondedDevices();
> if(pairedDevices.size() > 0)
> {
> for(BluetoothDevice device : pairedDevices)
> {
> if(device.getName().equals(strValue2))
> {
> mmDevice = device;
> break;
> }
> }
> }
> myLabel.setText("Bluetooth Device Found");
> }
>
> void openBT() throws IOException
> {
> UUID uuid = UUID.fromString("00001101-0000-1000-8000-00805f9b34fb");
> //Standard SerialPortService ID
> mmSocket = mmDevice.createRfcommSocketToServiceRecord(uuid);
> mmSocket.connect();
> mmOutputStream = mmSocket.getOutputStream();
> mmInputStream = mmSocket.getInputStream();
>
> myLabel.setText("Bluetooth Opened");
> }
>
> void sendData(String msg) throws IOException
> {
>
> msg += "\n";
> mmOutputStream.write(msg.getBytes());
> myLabel.setText("Data Sent");
> }
>
> void beginListenForData()
> {
> final Handler handler = new Handler();
> final byte delimiter = 10; //This is the ASCII code for a newline
> character
>
> stopWorker = false;
> readBufferPosition = 0;
> readBuffer = new byte[1024];
> workerThread = new Thread(new Runnable()
> {
> public void run()
> {
> while(!Thread.currentThread().isInterrupted() && !stopWorker)
> {
> try
> {
> int bytesAvailable =
> mmInputStream.available();
> if(bytesAvailable > 0)
> {
> byte[] packetBytes = new byte[bytesAvailable];
> mmInputStream.read(packetBytes);
> for(int i=0;i<bytesAvailable;i++)
> {
> byte b = packetBytes[i];
> if(b == delimiter)
> {
> byte[] encodedBytes = new
> byte[readBufferPosition];
> System.arraycopy(readBuffer, 0,
> encodedBytes, 0, encodedBytes.length);
> //final String data = new
> String(encodedBytes, "US-ASCII");
> data = new String(encodedBytes,
> "US-ASCII");
>
>
> readBufferPosition = 0;
>
> handler.post(new Runnable()
> {
> public void run()
> {
> temptext.setText(data);
>
> }
> });
> }
> else
> {
> readBuffer[readBufferPosition++] = b;
> }
> }
> }
> }
> catch (IOException ex)
> {
> stopWorker = true;
> }
> }
> }
> });
>
> workerThread.start();
> }
>
>
> public void Setup(View view) throws IOException
> {
> killMe = true;
> work=false;
> stopWorker = true;
> mmOutputStream.close();
> mmInputStream.close();
> mmSocket.close();
> //mBluetoothAdapter.disable();
> myLabel.setText("Bluetooth Closed");
> Intent intent = new Intent();
> setResult(RESULT_OK, intent);
> finish();
> }
>
> protected void onStop()
> {
>
> super.onStop();
> killMe = true;
> work=false;
> stopWorker = true;
> try {
> mmOutputStream.close();
> mmInputStream.close();
> mmSocket.close();
> } catch (IOException e) {
> // TODO Auto-generated catch block
> e.printStackTrace();
> }
>
> mBluetoothAdapter.disable();
> myLabel.setText("Bluetooth Closed");
> finish();
>
> }
>
> @Override
> protected void onDestroy() {//android has killed this activity
> //Log.d(logtag,"onDestroy() called");
> super.onDestroy();
> mBluetoothAdapter.disable();
> try {
> mmOutputStream.close();
> mmInputStream.close();
> mmSocket.close();
> } catch (IOException e) {
> // TODO Auto-generated catch block
> e.printStackTrace();
> }
> killMe = true;
> finish();
> }
> }
> *
>
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