getRemoteDevice gibt einen Fehler

Question

Ich mache eine Bluetooth-Anwendung mit Java. Ich habe eine Devicelist-Aktivität erstellt, um alle gekoppelten Geräte und neu erkannten Geräte anzuzeigen. Wenn ich diese Aktivität über die Elternaktivität öffne und auf ein Gerät klicke, wird die MAC-Adresse von der Geräteliste an die Elternaktivität gesendet, aber sobald ich versuche, das Bluetooth-Gerät zu entfernen, stürzt meine App ab (Logcat ist unten).

DeviceList.java

public static String EXTRA_DEVICE_ADDRESS = "device_address"; 

private final BroadcastReceiver mReceiver = new BroadcastReceiver() { 
    @Override 
    public void onReceive(Context context, Intent intent) { 
     String action = intent.getAction(); 

     // When discovery finds a device 
     if (BluetoothDevice.ACTION_FOUND.equals(action)) { 
      // Get the BluetoothDevice object from the Intent 
      BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE); 
      // If it's already paired, skip it, because it's been listed already 
      if (device.getBondState() != BluetoothDevice.BOND_BONDED) { 
       mNewDevicesArrayAdapter.add(device.getName() + "\n" + device.getAddress()); 
      } 
     } 
    } 
} 

private AdapterView.OnItemClickListener mDeviceClickListener = new AdapterView.OnItemClickListener() { 
    public void onItemClick(AdapterView<?> av, View v, int arg2, long arg3) { 
     // Cancel discovery because it's costly and we're about to connect 
     mBtAdapter.cancelDiscovery(); 

     // Get the device MAC address, which is the last 17 chars in the View 
     String info = ((TextView) v).getText().toString(); 
     String address = info.substring(info.length() - 17); 

     // Create the result Intent and include the MAC address 
     Intent data = new Intent(); 
     data.putExtra(EXTRA_DEVICE_ADDRESS, address); 

     // Set result and finish(=close?) this Activity 
     setResult(RESULT_OK, data); 
     finish(); 
    } 
}; 

TribotActivity (meine Eltern-Klasse)

@Override 
protected void onActivityResult(int requestCode, int resultCode, Intent data) { 
    if (requestCode == REQUEST_DEVICE_ADDRESS) {  // Check which request we're responding to. When doing more requests a switch case is probably a nicer way of doing this. 
     if (resultCode == RESULT_OK) {     // Make sure the request was successful 
      if (data.hasExtra("device_address")) { 
       Bundle bundleResult = data.getExtras(); // Store the Intent data(=device address) that we've received from the DeviceListActivity TODO Figure out why we can't simply use "String device = data.getStringExtra("device");" 
       String address = bundleResult.getString("EXTRA_DEVICE_ADDRESS"); 
       //String address = data.getExtras().getString(DeviceListActivity.EXTRA_DEVICE_ADDRESS); 
       BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(address); 

       //BluetoothConnect.connect(device); 

       textView = (TextView) findViewById(R.id.textView2); 
       textView.setText("Device address: " + address); 
      } else { 
       Toast.makeText(getApplicationContext(), "Failed to get MAC address", Toast.LENGTH_SHORT).show(); //TODO Remove this when we've successfully sent through the address 
      } 
     } else { 
      Toast.makeText(getApplicationContext(), "Failed to get MAC address", Toast.LENGTH_SHORT).show(); //TODO Remove this when we've successfully sent through the address 
     } 
    } 
}; 

ich tun, um die MAC-Adresse des putExtra bekommen. Ich zeige es sogar auf einem textView, um sicherzustellen, dass ich die richtige Adresse bekomme, aber jedes Mal, wenn ich versuche, das BluetoothDevice daraus zu holen, stürzt meine App ab.

Log

04-04 12:12:50.638 10364-10364/com.hszuyd.noodle_.testing E/AndroidRuntime: FATAL EXCEPTION: main 
    Process: com.hszuyd.noodle_.testing, PID: 10364 
    Theme: themes:{} 
    java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=1, result=-1, data=Intent { (has extras) }} to activity {com.hszuyd.noodle_.testing/com.hszuyd.noodle_.testing.TribotActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.bluetooth.BluetoothDevice android.bluetooth.BluetoothAdapter.getRemoteDevice(java.lang.String)' on a null object reference 
    at android.app.ActivityThread.deliverResults(ActivityThread.java:3733) 
    at android.app.ActivityThread.handleSendResult(ActivityThread.java:3776) 
    at android.app.ActivityThread.-wrap16(ActivityThread.java) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1412) 
    at android.os.Handler.dispatchMessage(Handler.java:102) 
    at android.os.Looper.loop(Looper.java:148) 
    at android.app.ActivityThread.main(ActivityThread.java:5461) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
    at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:117) 
    Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.bluetooth.BluetoothDevice android.bluetooth.BluetoothAdapter.getRemoteDevice(java.lang.String)' on a null object reference 
    at com.hszuyd.noodle_.testing.TribotActivity.onActivityResult(TribotActivity.java:88) 
    at android.app.Activity.dispatchActivityResult(Activity.java:6456) 
    at android.app.ActivityThread.deliverResults(ActivityThread.java:3729) 
    at android.app.ActivityThread.handleSendResult(ActivityThread.java:3776) 
    at android.app.ActivityThread.-wrap16(ActivityThread.java) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1412) 
    at android.os.Handler.dispatchMessage(Handler.java:102) 
    at android.os.Looper.loop(Looper.java:148) 
    at android.app.ActivityThread.main(ActivityThread.java:5461) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
    at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:117) 

Ich hoffe, euch kann mir helfen! Danke.

Answer 1

Auf den ersten Blick: Runtime: versuchen Bearbeitung Textview-Code in diese zu wickeln:

synchronized (this) { 
     runOnUiThread(new Runnable() { 
      @Override 
      public void run() { 
       textView = (TextView) findViewById(R.id.textView2); 
       textView.setText("Device address: " + address); 
      } 
     }); 
    } 

Nullpointer: Ich in Ihrer Variante nicht sicher, Remote-Gerät zu bekommen. In meinem Server-Side-Code dies funktioniert:

 serverSocket = bluetoothAdapter.listenUsingRfcommWithServiceRecord(SERVICE_NAME, java.util.UUID.fromString(UUID)); 
     clientSocket = serverSocket.accept(); 
     if (clientSocket != null) 
      clientDevice = clientSocket.getRemoteDevice(); //remember client 

Und auf Client-Seite:

private final BroadcastReceiver discoveryStartedReceiver = new BroadcastReceiver() { 
     @Override 
     public void onReceive(Context context, Intent intent) { 
      String action = intent.getAction(); 
      // When discovery finds a device 
      if (BluetoothDevice.ACTION_FOUND.equals(action)) { 
       // Get the BluetoothDevice object from the Intent 
       BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE); 
       discoveredDevices.add(device); 
       // Add the name and address to an array adapter to show in a ListView 
       btDevicesAdapterList.add(device.getName() + "\n" + device.getAddress()); 

       //TODO 
       if ((device.getName().equals(ROBOT_SERVER_NAME))){ 
        if (clientState != CLIENT_CONNECTING) { 
         selectedServer = device; 
         Log.i(TAG, "SelectedServer: " + selectedServer.getName()); 
         bluetoothAdapter.cancelDiscovery(); 
         connectMethod(); 
        } 
       } 
      } 
     } 
    };