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copied!<p>Regarding "strange NPE" - it's not strange at all. The reason you get NPE at this line</p> <pre><code>socket = mmServerSocket.accept(); //THIS LINE CAUSES NPE </code></pre> <p>is pretty obvious - variable <em>mmServerSocket</em> equals NULL, and this is the only possible reason to get NPE at this line of code. The reason why <em>mmServerSocket</em> equals NULL is simple too - look at a constructor of your class:</p> <pre><code>public AcceptThread() { BluetoothServerSocket tmp = null; try { tmp = mAdapter.listenUsingRfcommWithServiceRecord(NAME, MY_UUID); } catch (IOException e) { Log.e(TAG, "listen() failed", e); } mmServerSocket = tmp; } </code></pre> <p>You are calling method <code>listenUsingRfcommWithServiceRecord</code> which throws IOException, you catching this exception, as we can clearly see in logcat. Next, <code>tmp</code> variable stays initialized as NULL, same as <code>mmServerSocket</code>, which leads as to NPE mentioned above.</p> <p>The reason why <code>listenUsingRfcommWithServiceRecord</code> is throwing IOException - because bluetooth is turned off, as you mention in your question. Android documentation says nothing about your assumption that this method should automatically turn on bluetooth if it's turned off. I think you should manually check if bluetooth is turned off and turn it on manually, before calling <code>listenUsingRfcommWithServiceRecord</code>.</p> <p>You can find how to check is bluetooth turned on/off and turn it on <a href="https://stackoverflow.com/questions/6546083/how-to-turn-on-bluetooth-on-button-click">here</a> and <a href="https://stackoverflow.com/questions/1975655/enable-android-bluetooth-from-documentation">here</a></p>

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