title: Why the "" BluetoothAdapter﹕ startLeScan(): null "" happened when BLE Scan in Android?
body: <p>I am developing in Android for BLE. My BLE device will broadcast for different name , so I need to continue re-scan Android.</p>
  
  <p>I create a <code>Runnable</code> to stop and start scan like the following. When I call <code>mHandler.post(monitorDevice);</code> , it will start the <code>Runnable</code>.</p>
  
  <pre><code>final Runnable monitorDevice = new Runnable() {
      @Override
      public void run() {
          scanLeDevice(false);
          scanLeDevice(true);
          mHandler.postDelayed(this,3000);
      }
  };
  </code></pre>
  
  <p>The code of <code>scanLeDevice</code> is like the following:</p>
  
  <pre><code>public void scanLeDevice(final boolean enable) {
                  // TODO Auto-generated method stub
                  if(enable){
                      mScanning = true;
                      mBluetoothAdapter.startLeScan(mLeScanCallback);
  
                  }else {
                      mScanning = false;
                      mBluetoothAdapter.stopLeScan(mLeScanCallback);
                  }
              }
  </code></pre>
  
  <p>I can see the scan result in the log at the begin. But after about 10~15 minute , the logcat show the following log , and I can not seen any scan result.</p>
  
  <pre><code>startLeScan(): null
  D/BluetoothLeScanner﹕ onClientRegistered() - status=0 clientIf=5
  </code></pre>
  
  <p>Does someone has this problem ? Thanks in advance!!!</p>