Question

我在我的应用程序中使用蓝牙连接热敏打印机。首先，我检查蓝牙是否启用，一切正常。但是当我在应用程序中关闭蓝牙时，我遇到了问题。我的应用程序崩溃时出现空指针异常，该异常未在BluetoothService类中处理。

此外，我注意到即使我不在我的应用程序中并关闭蓝牙，它也会调用我的应用程序并向我显示来自我的代码的祝酒消息。

任何人都面临这个问题？

这是来自蓝牙服务器套接字的空指针异常

03-03 17:13:27.576 9916-10431/co.lvlz.skiplino.provider E/AndroidRuntime: FATAL EXCEPTION: AcceptThread Process: co.lvlz.skiplino.provider, PID: 9916
java.lang.NullPointerException: Attempt to invoke virtual method 'android.bluetooth.BluetoothSocket 
android.bluetooth.BluetoothServerSocket.accept()' on a null object reference at com.zj.btsdk.BluetoothService$AcceptThread.run(BluetoothService.java:316)

此处处理蓝牙以及如何销毁活动

private final Handler mHandler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
                case BluetoothService.MESSAGE_STATE_CHANGE:
                    switch (msg.arg1) {
                        case BluetoothService.STATE_CONNECTED:   
                            Toast.makeText(getApplicationContext(), "Connect successful",
                                    Toast.LENGTH_SHORT).show();

                            break;
                        case BluetoothService.STATE_CONNECTING:  
                            Log.d("��������","��������.....");
                            break;
                        case BluetoothService.STATE_LISTEN:    
                        case BluetoothService.STATE_NONE:

                       Toast.makeText(getApplicationContext(), "bluetooth is closed",
                                    Toast.LENGTH_SHORT).show();

                            Log.d("None", "stateNone");
                            MainActivity.this.finish();


                            break;
                    }


                    break;

                case BluetoothService.MESSAGE_CONNECTION_LOST:
                    Log.d("None", "connection lost to device");

                Toast.makeText(getApplicationContext(),"Connetion was lost to device",
                            Toast.LENGTH_SHORT).show();


                    break;
                case BluetoothService.MESSAGE_UNABLE_CONNECT:
                    Toast.makeText(getApplicationContext(), "Unable to connect device",
                            Toast.LENGTH_SHORT).show();

                    break;
            }
        }

    };




protected void onDestroy() {
        super.onDestroy();
        if (mService != null)
        {

            Log.d("None", "nullMe");
            activitydestroyed=true;
            mService.stop();


        }

        else {
            Log.d("None", "nullMe2");
            mService = null;

        }
    }

蓝牙服务器插座android

0 个答案: