Java 蓝牙GATT试图调用虚拟方法'；void android.content.Context.sendBroadcast（android.content.Intent）和#x27；关于空对象引用

我正在编写我的第一个android应用程序，但已经失败了——我对蓝牙GATT读写的可靠性产生了很大的质疑。30分钟前，我能够将手机中的一个字节写入外设，并看到它被接收。现在我不能。我开始认为这个间歇性错误是导致问题的原因：

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)

我从android开发人员示例中获得了大部分代码，但根据需要对其进行了修改。如果我在此处删除对broadcastUpdate的调用，或将其包装在一个try块中，则错误将发生在不同的位置（例如OnServicesDiscoveryd），但该错误仅出现一次

这是我绑定服务的地方：

@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);
    }
}

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;
    }
};

这是服务：

@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);
    }
}

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;
    }
};

以下是发生错误的回调处理程序：

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");
    }
};

广播更新：

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

---

我非常困惑，我甚至不确定解决这个问题是否能解决我的问题

我不知道这是否能帮助您，但我收到了完全相同的错误消息。关于我的问题的一些上下文：我在我的自定义对象中的活动之外调用“sendBroadcast”。我可以通过替换以下内容来解决此问题：

sendBroadcast(intent);

为此：

context.sendBroadcast(intent);

不用说，当活动第一次实例化所述对象时，通过将上下文传递给构造函数中的对象，我在对象中保留了对上下文的引用：

new MyObject(this);

---

希望它能帮助您。

广播更新在哪里方法代码？如果您只需要应用程序内部广播，请不要使用

sendBroadcast（intent）

。为了提高效率和安全性，请更好地使用

LocalBroadcastManager.getInstance（this）.sendBroadcast（intent）

我最终修复了它，但我不知道它是如何消失的，我将回顾我的问题并比较源代码，看看是否可以缩小范围。谢谢你的回答，你有没有想过？我有一个类似的问题，我想知道您发现了什么将sendBroadcast（intent）更改为上下文。sendBroadcast（intent）确实解决了问题>>>我在活动之外调用“sendBroadcast”这是一个奇怪的说法。无法从任意对象调用sendBroadcast，因为此方法是上下文类的成员