Bluetooth GATT尝试在空对象引用上调用虚拟方法的void android.content.Context.sendBroadcast(android.content.Intent)‘
Bluetooth GATT尝试在空对象引用上调用虚拟方法的void android.content.Context.sendBroadcast(android.content.Intent)‘
提问于 2015-02-09 12:14:54
我正在编写我的第一个android应用程序，但却遇到了问题--蓝牙GATT的读写可靠性有很大问题。30分钟前，我能够从我的手机向我的外设写入一个字节，并看到它被接收到。现在我不能了。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。如果我在这里删除对broadcastUpdate的调用，或者将它包装在一个try块中，错误将在不同的位置(例如onServicesDiscovered)发生相同的错误，但它只出现一次。
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);
}
}这就是服务：
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");
}
};broadcastUpdate：
private void broadcastUpdate(final String action) {
final Intent intent = new Intent(action);
sendBroadcast(intent);
}我被难住了，我甚至不确定解决这个问题是否能解决我的问题
回答 1
Stack Overflow用户
发布于 2015-04-17 07:32:14
我不知道这是否会对您有帮助，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一个活动之外调用了'sendBroadcast‘。我能够通过替换这个来解决这个问题：
sendBroadcast(intent);有了这个：
context.sendBroadcast(intent);不用说，当活动第一次实例化所述对象时，通过在其构造函数中将其传递给对象，我在对象中保留了对上下文的引用：
new MyObject(this);希望能对你有所帮助。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/28402728
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