Nexus 4上BluetoothGatt.java中的NullPointerException

Question

I am disconnecting and closing a bluetooth GATT instance and see the following in logcat:

07-22 09:33:20.699    5095-5113/com.assaabloy.stg.cliqconnect.android W/BluetoothGatt﹕ Unhandled exception in callback
java.lang.NullPointerException
        at android.bluetooth.BluetoothGatt$1.onClientConnectionState(BluetoothGatt.java:168)
        at android.bluetooth.IBluetoothGattCallback$Stub.onTransact(IBluetoothGattCallback.java:71)
        at android.os.Binder.execTransact(Binder.java:404)
        at dalvik.system.NativeStart.run(Native Method)

Here are the native events that immediately precede this error:

07-22 09:33:20.689    1260-1277/? D/BtGatt.GattService﹕ clientDisconnect() - address=84:EB:18:44:D2:04, connId=9
07-22 09:33:20.689    1260-1277/? D/BtGatt.btif﹕ btif_gattc_close
07-22 09:33:20.689    1260-1322/? D/BtGatt.btif﹕ btgattc_handle_event: Event 1005
07-22 09:33:20.689    1260-1568/? E/bt-btif﹕ Do not find the bg connection mask for the remote device
07-22 09:33:20.689    1260-1322/? D/BtGatt.btif﹕ btif_gattc_upstreams_evt: Event 5
07-22 09:33:20.689    1260-1322/? D/BtGatt.GattService﹕ onDisconnected() - clientIf=9, connId=9, address=84:EB:18:44:D2:04
07-22 09:33:20.689    1260-1328/? D/BtGatt.GattService﹕ unregisterClient() - clientIf=9
07-22 09:33:20.689    1260-1328/? D/BtGatt.btif﹕ btif_gattc_unregister_app

OS version: Android 4.4.4

Device: Nexus 4

Can someone please explain what's going on?

Answer 1

It seems you can't call these method together. The disconnection callback might arrive later than close() method performed.

You can add mGatt.close(); into onConnectionStateChange callback to close the connection.

check this link

Answer 2

At this position BluetoothGatt tries to call onConnectionStateChange(...) on your BluetoothGattCallback instance.

Have you overridden that one?

private final BluetoothGattCallback gattCallback = new BluetoothGattCallback() {
        @Override
        public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
        ...
        }
}

Answer 3

I got a similar exception on Samsung SM G318H, "Trend 2 Lite":

D/BluetoothGatt( 4182): onClientConnectionState() - status=0 clientIf=6 device=D0:5F:B8:57:FE:33
W/BluetoothGatt( 4182): Unhandled exception in callback
W/BluetoothGatt( 4182): java.lang.NullPointerException
W/BluetoothGatt( 4182): at android.bluetooth.BluetoothGatt$1.onClientConnectionState(BluetoothGatt.java:172)
W/BluetoothGatt( 4182): at android.bluetooth.IBluetoothGattCallback$Stub.onTransact(IBluetoothGattCallback.java:71)
W/BluetoothGatt( 4182): at android.os.Binder.execTransact(Binder.java:404)
W/BluetoothGatt( 4182): at dalvik.system.NativeStart.run(Native Method)

when trying to reconnect from inside the state change handler:

public final void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {

  switch (newState) {
     case BluetoothProfile.STATE_DISCONNECTED:
       device.connectGatt(...);
       break;
  }

}

and solved it by moving the reconnect to a timer thread:

    case BluetoothProfile.STATE_DISCONNECTED:
      timer.schedule(
        new TimerTask() {
          @Override
          public void run() {
            device.connectGatt(...);
          }
        }, 3000);
      break;

Answer 4

One solution is just invoke disconnect() on BluetoothGatt object. Call the close() in OnConnectionStateChange() callback.