藍牙GATT嘗試調用虛擬方法'void android.content.Context.sendBroadcast（android.content.Intent）'null對象引用

Question

我正在編寫我的第一個android應用程序，並且已經脫鉤 - 我越來越大問題與藍牙GATT的可靠性讀取和寫入。 30分鐘前，我能夠從手機寫入一個字節到我的外設，並看到它收到。我現在不可以。我王建宇，山西高等學校認爲這陣性錯誤是造成問題的一個：

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.content.Context.sendBroadcast(android.content.Intent)' on a null object reference 
     at android.content.ContextWrapper.sendBroadcast(ContextWrapper.java:376) 
     at com.znewsham.skiday.adapters.BluetoothLeService.broadcastUpdate(BluetoothLeService.java:152) 
     at com.znewsham.skiday.adapters.BluetoothLeService.access$100(BluetoothLeService.java:50) 
     at com.znewsham.skiday.adapters.BluetoothLeService$1.onServicesDiscovered(BluetoothLeService.java:118) 
     at android.bluetooth.BluetoothGatt$1.onSearchComplete(BluetoothGatt.java:304) 
     at android.bluetooth.IBluetoothGattCallback$Stub.onTransact(IBluetoothGattCallback.java:217) 
     at android.os.Binder.execTransact(Binder.java:454) 

我得到了大多數來自Android開發者的例子代碼，但修改了它對於我的需求。如果我在此刪除對broadcastUpdate的調用，或者將它包裝在try塊中，則錯誤將發生在不同位置（例如onServicesDiscovered）的同一錯誤，但它只出現一次。

這是我綁定服務：

@Override 
protected void onActivityResult(int requestCode, int resultCode, Intent data) { 
    if(requestCode == DEVICE_SCAN){ 
     address = data.getStringExtra("address"); 
     Intent gattServiceIntent = new Intent(this, BluetoothLeService.class); 
     startService(gattServiceIntent); 
     bindService(gattServiceIntent, mServiceConnection, BIND_AUTO_CREATE); 
    } 
} 

這是服務：

private final ServiceConnection mServiceConnection = new ServiceConnection() { 
    @Override 
    public void onServiceConnected(ComponentName componentName, IBinder service) { 
     boolean connected; 
     do { 
      bluetoothLeService = ((BluetoothLeService.LocalBinder) service).getService(); 
      bluetoothLeService.attachBase(ViewSkiDayActivity.this); 
      if (!bluetoothLeService.initialize()) { 
       Log.e("", "Unable to initialize Bluetooth"); 
       finish(); 
      } 
      // Automatically connects to the device upon successful start-up initialization. 
      connected = bluetoothLeService.connect(address); 
     }while(connected == false); 
    } 
    @Override 
    public void onServiceDisconnected(ComponentName componentName) { 
     bluetoothLeService = null; 
    } 
}; 

這裏是哪裏發生錯誤的回調處理程序：

private final BluetoothGattCallback mGattCallback = new BluetoothGattCallback() { 
    @Override 
    public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) { 
     String intentAction; 
     if (newState == BluetoothProfile.STATE_CONNECTED) { 
      intentAction = ACTION_GATT_CONNECTED; 
      mConnectionState = STATE_CONNECTED; 
      try{ 
       broadcastUpdate(intentAction); 
      } 
      catch(Exception e){ 

      } 
      Log.i(TAG, "Connected to GATT server."); 
      // Attempts to discover services after successful connection. 
      Log.i(TAG, "Attempting to start service discovery:" + mBluetoothGatt.discoverServices()); 

     } else if (newState == BluetoothProfile.STATE_DISCONNECTED) { 
      intentAction = ACTION_GATT_DISCONNECTED; 
      mConnectionState = STATE_DISCONNECTED; 
      Log.i(TAG, "Disconnected from GATT server."); 
      try{ 
       broadcastUpdate(intentAction); 
      } 
      catch(Exception e){ 

      } 
     } 
    } 

    @Override 
    public void onServicesDiscovered(BluetoothGatt gatt, int status) { 
     if (status == BluetoothGatt.GATT_SUCCESS) { 
      broadcastUpdate(ACTION_GATT_SERVICES_DISCOVERED); 
     } else { 
      Log.w(TAG, "onServicesDiscovered received: " + status); 
     } 
    } 

    @Override 
    public void onCharacteristicRead(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) { 
     if (status == BluetoothGatt.GATT_SUCCESS) { 
      broadcastUpdate(ACTION_DATA_AVAILABLE, characteristic); 
     } 
    } 

    @Override 
    public void onCharacteristicChanged(BluetoothGatt gatt, final BluetoothGattCharacteristic characteristic) { 
     broadcastUpdate(ACTION_DATA_AVAILABLE, characteristic); 
    } 

    @Override 
    public void onCharacteristicWrite(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) { 
     Log.w("BLARG", "write callback"); 
    } 
}; 

broadcastUpdate：

private void broadcastUpdate(final String action) { 
    final Intent intent = new Intent(action); 
    sendBroadcast(intent); 
} 

我很爲難，我不太確定在解決這個問題將解決我的問題

Answer 1

我不知道這是否會幫助你，但我有完全相同的錯誤信息。對於我的問題的某些背景：我在我的自定義對象的Activity外調用了「sendBroadcast」。我能夠通過更換該解決：

sendBroadcast(intent); 

與此：

context.sendBroadcast(intent); 

不用說，我是保持在我對象的上下文的引用，將它傳遞給該對象在其構造，當活動首次實例化所述對象時：

new MyObject(this); 

希望它可以幫助你。