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POGetting a strange NPE in one of my Bluetooth classes, it didn't happen before
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copied!<p>Using Android's Bluetooth Chat sample app as my guide <a href="http://developer.android.com/resources/samples/BluetoothChat/index.html" rel="nofollow noreferrer">http://developer.android.com/resources/samples/BluetoothChat/index.html</a>, I've tried to create my own bluetooth function for an app I am working on.</p> <p>Last night I tested it with two Android phones and had some issues, but there were no force closes. It simply didn't connect my devices when I asked it to. I went in and added a few Log lines to make sure the program was following the proper course. When I reinstalled and launched the app on my phone today, I got a force close error when attempting to turn on Bluetooth, a problem I did not have at all last night. The only code I changed was the addition of 2-3 log commands. I checked logcat and got the following:</p> <p><img src="https://i.stack.imgur.com/oeB7W.png" alt="http://img708.imageshack.us/img708/143/logcatmysternpe.png"></p> <p>As you can see, the problem is caused by an NPE @ line 185. Here is my code for the BluetoothService class, I will repost the specific area of issue below it.</p> <pre><code>package com.tagapp.android; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.util.UUID; import android.bluetooth.BluetoothAdapter; import android.bluetooth.BluetoothDevice; import android.bluetooth.BluetoothServerSocket; import android.bluetooth.BluetoothSocket; import android.content.Context; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.util.Log; public class BluetoothService { private static final String TAG = "BluetoothService"; private static final boolean D = true; private static final String NAME = "BluetoothTag"; private static final UUID MY_UUID = UUID.fromString("93845760-234e-11e0-ac64-0800200c9a66"); private final BluetoothAdapter mAdapter; private final Handler mHandler; private AcceptThread mAcceptThread; private ConnectThread mConnectThread; private ConnectedThread mConnectedThread; private int mState; public static final int STATE_NONE = 0; public static final int STATE_LISTEN = 1; public static final int STATE_CONNECTING = 2; public static final int STATE_CONNECTED = 3; public BluetoothService(Context context, Handler handler) { mAdapter = BluetoothAdapter.getDefaultAdapter(); mState = STATE_NONE; mHandler = handler; } private synchronized void setState(int state) { if (D) Log.d(TAG, "setState() " + mState + " -> " + state); mState = state; mHandler.obtainMessage(BluetoothTransfer.MESSAGE_STATE_CHANGE, state, -1).sendToTarget(); } public synchronized int getState() { return mState; } public synchronized void start() { if (D) Log.d(TAG, "start"); if(mConnectThread != null) { mConnectThread.cancel(); mConnectThread = null; } if(mConnectedThread != null) { mConnectedThread.cancel(); mConnectedThread = null; } if(mAcceptThread == null) { mAcceptThread = new AcceptThread(); mAcceptThread.start(); } setState(STATE_LISTEN); } public synchronized void connect(BluetoothDevice device) { if (D) Log.d(TAG, "connect to: " + device); if(mState == STATE_CONNECTING) { if(mConnectThread != null) { mConnectThread.cancel(); mConnectThread = null; } } if(mConnectedThread != null) { mConnectedThread.cancel(); mConnectedThread = null; } mConnectThread = new ConnectThread(device); mConnectThread.start(); setState(STATE_CONNECTING); } public synchronized void connected(BluetoothSocket socket, BluetoothDevice device) { if (D) Log.d(TAG, "connected"); if(mConnectThread != null) { mConnectThread.cancel(); mConnectThread = null; } if(mConnectedThread != null) { mConnectedThread.cancel(); mConnectedThread = null; } if(mAcceptThread != null) { mAcceptThread.cancel(); mAcceptThread = null; } mConnectedThread = new ConnectedThread(socket); mConnectedThread.start(); Message msg = mHandler.obtainMessage(BluetoothTransfer.MESSAGE_DEVICE_NAME); Bundle bundle = new Bundle(); bundle.putString(BluetoothTransfer.DEVICE_NAME, device.getName()); msg.setData(bundle); mHandler.sendMessage(msg); setState(STATE_CONNECTED); } public synchronized void stop() { if (D) Log.d(TAG, "stop"); if(mConnectThread != null) { mConnectThread.cancel(); mConnectThread = null; } if(mConnectedThread != null) { mConnectedThread.cancel(); mConnectedThread = null; } if(mAcceptThread != null) { mAcceptThread.cancel(); mAcceptThread = null; } setState(STATE_NONE); } public void write(byte[] out) { ConnectedThread ct; synchronized(this) { if(mState != STATE_CONNECTED) return; ct = mConnectedThread; } ct.write(out); } private void connectionFailed() { setState(STATE_LISTEN); Message msg = mHandler.obtainMessage(BluetoothTransfer.MESSAGE_TOAST); Bundle bundle = new Bundle(); bundle.putString(BluetoothTransfer.TOAST, "Unable to connect device"); msg.setData(bundle); mHandler.sendMessage(msg); } private void connectionLost() { setState(STATE_LISTEN); Message msg = mHandler.obtainMessage(BluetoothTransfer.MESSAGE_TOAST); Bundle bundle = new Bundle(); bundle.putString(BluetoothTransfer.TOAST, "Device connection was lost"); msg.setData(bundle); mHandler.sendMessage(msg); } private class AcceptThread extends Thread { private final BluetoothServerSocket mmServerSocket; public AcceptThread() { BluetoothServerSocket tmp = null; try { tmp = mAdapter.listenUsingRfcommWithServiceRecord(NAME, MY_UUID); } catch (IOException e) { Log.e(TAG, "listen() failed", e); } mmServerSocket = tmp; } public void run() { if (D) Log.d(TAG, "BEGIN mAcceptThread" + this); setName("AcceptThread"); BluetoothSocket socket = null; while (mState != STATE_CONNECTED) { try { socket = mmServerSocket.accept(); } catch (IOException e) { Log.e(TAG, "accept() failed", e); break; } if(socket != null) { synchronized (BluetoothService.this) { switch(mState) { case STATE_LISTEN : case STATE_CONNECTING : connected(socket, socket.getRemoteDevice()); break; case STATE_NONE : case STATE_CONNECTED : try { socket.close(); } catch (IOException e) { Log.e(TAG, "Could not close unwanted socket", e); } break; } } } } if (D) Log.i(TAG, "END mAcceptThread"); } public void cancel() { if (D) Log.d(TAG, "cancel " + this); try { mmServerSocket.close(); } catch (IOException e) { Log.e(TAG, "close() of server failed", e); } } } private class ConnectThread extends Thread { private final BluetoothSocket mmSocket; private final BluetoothDevice mmDevice; public ConnectThread(BluetoothDevice device) { mmDevice = device; BluetoothSocket tmp = null; try { tmp = device.createRfcommSocketToServiceRecord(MY_UUID); } catch (IOException e) { Log.e(TAG, "create() failed", e); } mmSocket = tmp; } public void run() { Log.i(TAG, "BEGIN mConnectThread"); setName("ConnectThread"); mAdapter.cancelDiscovery(); try { mmSocket.connect(); } catch (IOException e) { connectionFailed(); try { mmSocket.close(); } catch (IOException e2) { Log.e(TAG, "unable to close() socket during connection failure", e2); } BluetoothService.this.start(); return; } synchronized (BluetoothService.this) { mConnectThread = null; } connected(mmSocket, mmDevice); } public void cancel() { try { mmSocket.close(); } catch (IOException e) { Log.e(TAG, "close() of connect socket failed", e); } } } private class ConnectedThread extends Thread { private final BluetoothSocket mmSocket; private final InputStream mmInStream; private final OutputStream mmOutStream; public ConnectedThread(BluetoothSocket socket) { Log.d(TAG, "create ConnectedThread"); mmSocket = socket; InputStream tmpIn = null; OutputStream tmpOut = null; try { tmpIn = socket.getInputStream(); tmpOut = socket.getOutputStream(); } catch (IOException e) { Log.e(TAG, "tempt sockets not created", e); } mmInStream = tmpIn; mmOutStream = tmpOut; } public void run() { Log.i(TAG, "BEGIN mConnectedThread"); byte[] buffer = new byte[1024]; int bytes; while (true) { try { bytes = mmInStream.read(buffer); mHandler.obtainMessage(BluetoothTransfer.CONTACT_RECEIVE, bytes, -1, buffer).sendToTarget(); } catch (IOException e) { Log.e(TAG, "disconnected", e); connectionLost(); break; } } } public void write(byte[] buffer) { try { mmOutStream.write(buffer); mHandler.obtainMessage(BluetoothTransfer.CONTACT_SEND, -1, -1, buffer).sendToTarget(); } catch (IOException e) { Log.e(TAG, "exception during write", e); } } public void cancel() { try { mmSocket.close(); } catch (IOException e) { Log.e(TAG, "close() of connect socket failed", e); } } } } </code></pre> <p>The lines which are causing the NPE (the AcceptThread):</p> <pre><code>private class AcceptThread extends Thread { private final BluetoothServerSocket mmServerSocket; public AcceptThread() { BluetoothServerSocket tmp = null; try { tmp = mAdapter.listenUsingRfcommWithServiceRecord(NAME, MY_UUID); } catch (IOException e) { Log.e(TAG, "listen() failed", e); } mmServerSocket = tmp; } public void run() { if (D) Log.d(TAG, "BEGIN mAcceptThread" + this); setName("AcceptThread"); BluetoothSocket socket = null; while (mState != STATE_CONNECTED) { try { socket = mmServerSocket.accept();//THIS LINE CAUSES NPE } catch (IOException e) { Log.e(TAG, "accept() failed", e); break; } </code></pre> <p>The object socket should by initialized @ null, but it is supposed to try socket = mmServerSocket.accept();</p> <p>This is directly from Google's sample app provided on the Android dev website. I have two concerns: 1, why isn't this working, and 2, why did it work just fine just hours ago?</p> <p>Thanks for your help.</p>

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