错误；应用程序可能在其主线程上工作过多。

这个问题已经有答案了:

应用程序在其主线程上执行的工作可能太多

我不知道为什么这个错误一直弹出。这是我的整个类;

public class MainActivity extends Activity {
// will show the statuses
TextView myLabel;
// will enable user to enter any text to be printed
EditText myTextbox;
// android built in classes for bluetooth operations
BluetoothAdapter mBluetoothAdapter;
BluetoothSocket mmSocket;
BluetoothDevice mmDevice;
OutputStream mmOutputStream;
InputStream mmInputStream;
Thread workerThread;
byte[] readBuffer;
int readBufferPosition;
int counter;
volatile boolean stopWorker;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    try {
        // we are goin to have three buttons for specific functions
        Button openButton = (Button) findViewById(R.id.open);
        Button sendButton = (Button) findViewById(R.id.send);
        Button closeButton = (Button) findViewById(R.id.close);
        myLabel = (TextView) findViewById(R.id.label);
        myTextbox = (EditText) findViewById(R.id.entry);
        // open bluetooth connection
        openButton.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                try {
                    findBT();
                    openBT();
                } catch (IOException ex) {
                }
            }
        });
        // send data typed by the user to be printed
        sendButton.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                try {
                    sendData();
                } catch (IOException ex) {
                }
            }
        });
        // close bluetooth connection
        closeButton.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                try {
                    closeBT();
                } catch (IOException ex) {
                }
            }
        });
    } catch (NullPointerException e) {
        e.printStackTrace();
    } catch (Exception e) {
        e.printStackTrace();
    }
}
/*
 * This will find a bluetooth printer device
 */
void findBT() {
    try {
        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, 0);
        }
        Set pairedDevices = mBluetoothAdapter
                .getBondedDevices();
        if (pairedDevices.size() > 0) {
            for (BluetoothDevice device : pairedDevices) {
                // MP300 is the name of the bluetooth printer device
                if (device.getName().equals("Star Micronics")) {
                    mmDevice = device;
                    break;
                }
            }
        }
        myLabel.setText("Bluetooth Device Found");
    } catch (NullPointerException e) {
        e.printStackTrace();
    } catch (Exception e) {
        e.printStackTrace();
    }
}
/*
 * Tries to open a connection to the bluetooth printer device
 */
void openBT() throws IOException {
    try {
        // Standard SerialPortService ID
        UUID uuid = UUID.fromString("00001101-0000-1000-8000-00805f9b34fb");
        mmSocket = mmDevice.createRfcommSocketToServiceRecord(uuid);
        mmSocket.connect();
        mmOutputStream = mmSocket.getOutputStream();
        mmInputStream = mmSocket.getInputStream();
        beginListenForData();
        myLabel.setText("Bluetooth Opened");
    } catch (NullPointerException e) {
        e.printStackTrace();
    } catch (Exception e) {
        e.printStackTrace();
    }
}
/*
 * After opening a connection to bluetooth printer device, 
 * we have to listen and check if a data were sent to be printed.
 */
void beginListenForData() {
    try {
        final Handler handler = new Handler();
        // This is the ASCII code for a newline character
        final byte delimiter = 10;
        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");
                                    readBufferPosition = 0;
                                    handler.post(new Runnable() {
                                        public void run() {
                                            myLabel.setText(data);
                                        }
                                    });
                                } else {
                                    readBuffer[readBufferPosition++] = b;
                                }
                            }
                        }
                    } catch (IOException ex) {
                        stopWorker = true;
                    }
                }
            }
        });
        workerThread.start();
    } catch (NullPointerException e) {
        e.printStackTrace();
    } catch (Exception e) {
        e.printStackTrace();
    }
}
/*
 * Close the connection to bluetooth printer.
 */
void closeBT() throws IOException {
    try {
        stopWorker = true;
        mmOutputStream.close();
        mmInputStream.close();
        mmSocket.close();
        myLabel.setText("Bluetooth Closed");
    } catch (NullPointerException e) {
        e.printStackTrace();
    } catch (Exception e) {
        e.printStackTrace();
    }
}
/*
 * This will send data to be printed by the bluetooth printer
 */
void sendData() throws IOException {
    try {
        // the text typed by the user
        String msg = myTextbox.getText().toString();
        msg += "\n";
        mmOutputStream.write(msg.getBytes());
        // tell the user data were sent
        myLabel.setText("Data Sent");
        closeBT();
    } catch (NullPointerException e) {
        e.printStackTrace();
    } catch (Exception e) {
        e.printStackTrace();
    }
}
}//End of class

这段代码片段是一个单类应用程序，它应该打印文本字段中写入的任何内容，但当我检查配对设备时，它会出现标题中的错误。

有任何建议吗？？