Xamarin Android Bluetooth App Absturz

Question

Ich bin ein Anfänger in Android-App-Entwickler, und ich muss eine Bluetooth-App zum Verbinden mit dem HC-05-Modul machen. Mein Code ist wie folgt:

using System; 
using Android.App; 
using Android.Widget; 
using Android.OS; 
using Android.Bluetooth; 
using Android.Content; 
using Android.Runtime; 
using Java.Util; 
using Android.Util; 

namespace Robot_App 
{ 
    [Activity(Label = "Robot App", MainLauncher = true, Icon = "@drawable/logo", Theme = "@android:style/Theme.Light.NoTitleBar")] 
    public class MainActivity : Activity 
    { 
     BluetoothAdapter myAdapter = BluetoothAdapter.DefaultAdapter; 
     private static ArrayAdapter<string> newDevicesAdapter; 
     private BluetoothReceiver receiver; 

     const int REQUEST_ENABLE_BT = 1; 

     protected override void OnCreate(Bundle bundle) 
     { 
      base.OnCreate(bundle); 

      SetContentView(Resource.Layout.Main); 

      var scanButton = FindViewById<Button>(Resource.Id.BT_get_list); 
      scanButton.Click += (sender, e) => 
      { 
       try 
       { 
        if (myAdapter.IsEnabled) 
        { 
         DoDiscovery(); 
        } 
        else 
        { 
         Intent enableBTIntent = new Intent(BluetoothAdapter.ActionRequestEnable); 
         StartActivityForResult(enableBTIntent, REQUEST_ENABLE_BT); 
        } 
       } 
       catch (AndroidException ex) 
       { 
        Toast.MakeText(this, ex.ToString(), ToastLength.Short).Show(); 
       } 
      }; 

      newDevicesAdapter = new ArrayAdapter<string>(this, Resource.Layout.device_names); 
      Spinner newDevicesList = (Spinner)this.FindViewById<Spinner>(Resource.Id.Devices_list); 
      newDevicesList.Adapter = newDevicesAdapter; 

      receiver = new BluetoothReceiver(this); 
      var filter = new IntentFilter(BluetoothDevice.ActionFound); 
      RegisterReceiver(receiver, filter); 

      filter = new IntentFilter(BluetoothAdapter.ActionDiscoveryFinished); 
      RegisterReceiver(receiver, filter); 

      myAdapter = BluetoothAdapter.DefaultAdapter; 

      BluetoothSocket mySocket; 
      UUID my_uuid = UUID.FromString("00001101-0000-1000-8000-00805F9B34FB"); 

      var connectButton = FindViewById<Button>(Resource.Id.Connect); 
      connectButton.Click += (sender, e) => 
      { 
       BluetoothDevice selectedDevice = (BluetoothDevice)newDevicesList.SelectedItem; 
       if (myAdapter.BondedDevices.Contains(selectedDevice)) 
       { 
        mySocket = selectedDevice.CreateRfcommSocketToServiceRecord(my_uuid); 
        myAdapter.CancelDiscovery(); 
        mySocket.Connect(); 
       } 
       else if (!myAdapter.BondedDevices.Contains(selectedDevice)) 
       { 

       } 
      }; 
     } 

     protected override void OnActivityResult(int requestCode, [GeneratedEnum] Result resultCode, Intent data) 
     { 
      switch (requestCode) 
      { 
       case (REQUEST_ENABLE_BT): 
        base.OnActivityResult(requestCode, resultCode, data); 
        if (resultCode == Result.Ok) 
        { 
         DoDiscovery(); 
        } 
        else if (resultCode == Result.Canceled) 
        { 
         Toast.MakeText(this, "Please switch on Bluetooth.", ToastLength.Long).Show(); 
        } 
        break; 
      } 
     } 

     private void DoDiscovery() 
     { 
      try 
      { 
       newDevicesAdapter.Clear(); 
       myAdapter.StartDiscovery(); 
       Toast.MakeText(this, "Searching...", ToastLength.Long).Show(); 
      } 
      catch (AndroidException ex) 
      { 
       Toast.MakeText(this, ex.ToString(), ToastLength.Short).Show(); 
      } 
     } 

     public class BluetoothReceiver : BroadcastReceiver 
     { 
      Activity _controller; 

      public BluetoothReceiver(Activity controller) 
      { 
       _controller = controller; 
      } 

      public override void OnReceive(Context context, Intent intent) 
      { 
       string action = intent.Action; 
       if (action == BluetoothDevice.ActionFound) 
       { 
        BluetoothDevice device = (BluetoothDevice)intent.GetParcelableExtra(BluetoothDevice.ExtraDevice); 
        newDevicesAdapter.Add(device.Name); 
       } 
       else if (action == BluetoothAdapter.ActionDiscoveryFinished) 
       { 
        Toast.MakeText(context, "Finished scanning for devices.", ToastLength.Short).Show(); 
       } 
      } 
     } 


    } 
} 

EDIT: Hier ist das Layout:

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:orientation="vertical" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:id="@+id/linearLayout1"> 
    <LinearLayout 
     android:orientation="horizontal" 
     android:id="@+id/linearLayout2" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content"> 
     <ImageView 
      android:src="@drawable/logo" 
      android:layout_width="120dp" 
      android:layout_height="100dp" 
      android:id="@+id/imageView1" 
      android:clickable="false" 
      android:visibility="visible" 
      android:padding="5dp" 
      android:layout_gravity="center" 
      android:layout_marginLeft="10dp" 
      android:layout_marginTop="5dp" /> 
     <LinearLayout 
      android:orientation="vertical" 
      android:layout_width="235.0dp" 
      android:layout_height="match_parent" 
      android:id="@+id/linearLayout3"> 
      <TextView 
       android:text="Robot" 
       android:textAppearance="?android:attr/textAppearanceLarge" 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content" 
       android:id="@+id/textView1" 
       android:clickable="false" 
       android:editable="false" 
       android:enabled="true" 
       android:longClickable="false" 
       android:padding="15dp" 
       android:layout_gravity="center" 
       android:gravity="center" /> 
      <TextView 
       android:text="Control Panel" 
       android:textAppearance="?android:attr/textAppearanceMedium" 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content" 
       android:id="@+id/textView2" 
       android:clickable="false" 
       android:editable="false" 
       android:enabled="true" 
       android:longClickable="false" 
       android:padding="5dp" 
       android:layout_gravity="center" 
       android:gravity="center" /> 
     </LinearLayout> 
    </LinearLayout> 
    <LinearLayout 
     android:orientation="vertical" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:id="@+id/BT_Connection"> 
     <TextView 
      android:text="Bluetooth Connection" 
      android:textAppearance="?android:attr/textAppearanceSmall" 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" 
      android:id="@+id/BT_Connection_tag" 
      android:clickable="false" 
      android:editable="false" 
      android:enabled="true" 
      android:longClickable="false" 
      android:paddingLeft="15dp" 
      android:paddingRight="15dp" 
      android:paddingTop="50dp" 
      android:layout_gravity="center" 
      android:gravity="left" 
      android:textSize="12dp" /> 
     <LinearLayout 
      android:orientation="horizontal" 
      android:minWidth="25px" 
      android:minHeight="25px" 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" 
      android:id="@+id/linearLayout4" 
      android:paddingLeft="15dp" 
      android:paddingRight="15dp" 
      android:paddingTop="5dp" 
      android:paddingBottom="5dp" 
      android:weightSum="3"> 
      <Button 
       android:text="Search" 
       android:layout_width="match_parent" 
       android:layout_height="match_parent" 
       android:id="@+id/BT_get_list" 
       android:clickable="true" 
       android:editable="false" 
       android:enabled="true" 
       android:longClickable="false" 
       android:layout_weight="1" 
       android:layout_gravity="center" /> 
      <Button 
       android:text="Connect" 
       android:layout_width="match_parent" 
       android:layout_height="match_parent" 
       android:id="@+id/Connect" 
       android:clickable="true" 
       android:editable="false" 
       android:enabled="true" 
       android:longClickable="false" 
       android:layout_gravity="center" 
       android:layout_weight="1" 
       android:gravity="center" /> 
      <Button 
       android:text="Disconnect" 
       android:layout_width="match_parent" 
       android:layout_height="match_parent" 
       android:id="@+id/Disconnect" 
       android:gravity="center" 
       android:layout_weight="1" 
       android:layout_gravity="center" 
       android:longClickable="false" 
       android:enabled="true" 
       android:editable="false" 
       android:clickable="true" /> 
     </LinearLayout> 
     <LinearLayout 
      android:orientation="horizontal" 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" 
      android:id="@+id/linearLayout5" 
      android:paddingBottom="5dp" 
      android:paddingLeft="15dp" 
      android:paddingRight="15dp"> 
      <Spinner 
       android:layout_width="match_parent" 
       android:layout_height="match_parent" 
       android:id="@+id/Devices_list" 
       android:clickable="true" 
       android:longClickable="false" 
       android:layout_gravity="center" 
       android:layout_weight="1" 
       android:tag="Please select a device:" /> 
     </LinearLayout> 
    </LinearLayout> 
</LinearLayout> 

Also im Grunde eine Schaltfläche Ich verwende für Geräte zu scannen, dann führe ich die gefundenen Geräte in einer Schleuder, dann verbindet sich eine Schaltfläche mit dem im Spinner ausgewählten Gerät.

Ich bekomme jedoch eine nicht behandelte Ausnahme, wenn ich auf die Schaltfläche "Suchen" klicke und die App abstürzt.

EDIT: Das ist, was ich in den VS2017 Debugger sehen:

Screenshot of debugger

Jede mögliche Hilfe geschätzt wird. Danke.

Answer 1

Haben Sie hinzugefügt diese

<uses-permission android:name="android.permission.BLUETOOTH" /> 
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" /> 

in Ihrem Manifest?