接收蓝牙发现的广播错误 - 通过startDiscovery（）方法接收Intent的onRecieve（）方法中的错误 [英] Receiving broadcast error for Bluetooth discovery - Error in onRecieve() method that receives intents by startDiscovery() Method

问题描述

我是Android的编程新手，我在设备扫描活动中面临一个问题。我想在附近的扫描所有蓝牙设备，并在UI上打印。但是，与接收蓝牙发现的广播错误。请帮助我调试我的代码。

  public class MainActivity extends ActionBarActivity {
 
 BluetoothAdapter mBluetoothAdapter; 
 private int REQUEST_ENABLE_BT = 1000; 
 public ArrayList< String> deviceArrayList = new ArrayList<>（）; 
 public ArrayList< BluetoothDevice> deviceList = new ArrayList<>（）; 
 
 @Override 
 protected void onCreate（Bundle savedInstanceState）{
 super.onCreate（savedInstanceState）; 
 setContentView（R.layout.activity_main）; 
} 
 
 @Override 
 protected void onResume（）{
 // TODO自动生成的方法存根
 super.onResume（）; 
 mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter（）; 
 if（mBluetoothAdapter == null）{
 //设备不支持蓝牙
 Toast.makeText（这个，设备不支持蓝牙!!!，Toast.LENGTH_LONG）。显示（）; 
 return; 
} 
 if（！mBluetoothAdapter.isEnabled（））{
 Intent enableBtIntent = new Intent（BluetoothAdapter.ACTION_REQUEST_ENABLE）; 
 startActivityForResult（enableBtIntent，REQUEST_ENABLE_BT）; 
} 
 scanStart（）; 
} 
 
 public void scanStart（）{
 // TODO自动生成的方法存根
 
 //将配对设备添加到ArrayList 
 addPairedDevices（）; 
 
 if（mBluetoothAdapter.isDiscovering（））{
 mBluetoothAdapter.cancelDiscovery（）; 
} 
 if（mBluetoothAdapter.startDiscovery（）== true）{
 Toast.makeText（this，Searching ...，Toast.LENGTH_LONG）.show（）; 
} 
 else {
 Toast.makeText（this，Bluetooth Adapter got Null Value，Toast.LENGTH_SHORT）.show（）; 
} 
 
 //注册BroadcastReceiver 
 IntentFilter filter = new IntentFilter（BluetoothDevice.ACTION_FOUND）; 
 this.registerReceiver（requestReciever，filter）; //在onDestroy中不要忘记取消注册
 
 try {
 Thread.sleep（12000）; 
} catch（InterruptedException e）{
 // TODO自动生成的catch块
 e.printStackTrace（）; 
} 
 
 //在UI上打印设备列表
 ListView lv = new ListView（this）; 
 ArrayAdapter< String> listAdapter = new ArrayAdapter（this，R.layout.print_device_list，deviceArrayList）; 
 lv.setAdapter（listAdapter）; 
 setContentView（lv）; 
 if（deviceArrayList.size（）< = 0）{
 Toast.makeText（this，No Devices Found ...，Toast.LENGTH_LONG）.show（）; 
} 
} 
 
 
 public void addPairedDevices（）{
 // TODO自动生成的方法存根
 //获取配对设备
设置< BluetoothDevice> pairsDevices = mBluetoothAdapter.getBondedDevices（）; 
 //如果配对设备
 if（pairsDevices.size（）> 0）{
 //循环配对设备
（BluetoothDevice设备：pairsDevices）{
 //将名称和地址添加到数组适配器中以在ListView中显示
 deviceArrayList.add（device.getName（）+\\\
+ device.getAddress（）+\\\
 + device.getUuids（）[0] .getUuid（））; 
 deviceList.add（device）; 
} 
} 
} 
 
 
 private BroadcastReceiver requestReciever = new BroadcastReceiver（）{
 
 public void onReceive（Context context ，意图意图）{
 if（intent == null）{
 return; 
} 
 String action = intent.getAction（）; 
 
 if（BluetoothDevice.ACTION_FOUND.equals（action））{
 Log.d（BT，Device Found）; 
 BluetoothDevice device = intent.getParcelableExtra（BluetoothDevice.EXTRA_DEVICE）; 
 if（device！= null）{
 if（device.getName（）！= null&&& device.getName（）。length（）> 0）{
 deviceArrayList。添加（device.getName（）+ \\\
 + device.getAddress（）+ \\\
 + device.getUuids（）[0] .getUuid（））; 
 deviceList.add（device）; 
} 
} 
} 
}; 
}; 
 
 
 @Override 
 protected void onActivityResult（int requestCode，int resultCode，Intent data）{
 // TODO自动生成的方法stub 
 super。 onActivityResult（requestCode，resultCode，data）; 
 
 if（requestCode == REQUEST_ENABLE_BT）{
 if（resultCode == Activity.RESULT_CANCELED）{
 Toast.makeText（this，Uesr不想打开蓝牙!!!，Toast.LENGTH_LONG）.show（）; 
 return; 
} 
} 
} 
 
 
 
 @Override 
 protected void onDestroy（）{
 // TODO自动生成的方法stub 
 super.onDestroy（）; 
 if（mBluetoothAdapter！= null）{
 mBluetoothAdapter.cancelDiscovery（）; 
} 
 if（requestReciever！= null）
 unregisterReceiver（requestReciever）; 
 Toast.makeText（this，Bluetooth App Stopped，Toast.LENGTH_LONG）.show（）; 
} 
} 
  

解决方案

code> device.getUuids（） - 这里你有一个Null，这就是为什么你在这里有一个错误。
检查这个变量是否使用它。

Hi I am new to android programming and i am facing a problem in device scan activity. I want to scan all bluetooth devices in vicinity and print them on UI. But i am getting the same run time error as in Receiving broadcast error for Bluetooth discovery. Please, please please help me to debug my code.

public class MainActivity extends ActionBarActivity {

    BluetoothAdapter mBluetoothAdapter;
    private int REQUEST_ENABLE_BT = 1000;
    public ArrayList<String> deviceArrayList = new ArrayList<>();
    public ArrayList<BluetoothDevice> deviceList = new ArrayList<>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    @Override
    protected void onResume() {
        // TODO Auto-generated method stub
        super.onResume();
        mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
        if (mBluetoothAdapter == null) {
            // Device does not support Bluetooth
            Toast.makeText(this, "Device Doesn't Support Bluetooth!!!", Toast.LENGTH_LONG).show();
            return;
        }
        if (!mBluetoothAdapter.isEnabled()) {
            Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
            startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT );
        }
        scanStart();
    }

    public void scanStart() {
        // TODO Auto-generated method stub

        //Adding Paired Devices into ArrayList
        addPairedDevices();

        if(mBluetoothAdapter.isDiscovering()){
            mBluetoothAdapter.cancelDiscovery();
        }
        if(mBluetoothAdapter.startDiscovery() == true){
            Toast.makeText(this, "Searching...", Toast.LENGTH_LONG).show();
        }
        else{
            Toast.makeText(this, "Bluetooth Adapter got Null Value", Toast.LENGTH_SHORT).show();
        }

        // Register the BroadcastReceiver
        IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
        this.registerReceiver(requestReciever, filter); // Don't forget to unregister during onDestroy  

        try {
            Thread.sleep(12000);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        //Printing Device List on UI
        ListView lv = new ListView(this);
        ArrayAdapter<String> listAdapter = new ArrayAdapter<>(this, R.layout.print_device_list, deviceArrayList);
        lv.setAdapter(listAdapter);
        setContentView(lv);
        if(deviceArrayList.size()<=0){
            Toast.makeText(this, "No Devices Found...", Toast.LENGTH_LONG).show();
        }
    }


    public void addPairedDevices() {
        // TODO Auto-generated method stub
        // get paired devices
        Set<BluetoothDevice> pairedDevices = mBluetoothAdapter.getBondedDevices();
        // If there are paired devices
        if (pairedDevices.size() > 0) {
            // Loop through paired devices
            for (BluetoothDevice device : pairedDevices) {
                // Add the name and address to an array adapter to show in a ListView
                deviceArrayList.add(device.getName() + "\n" + device.getAddress() + "\n" + device.getUuids()[0].getUuid());
                deviceList.add(device);
            }
        }
    }


    private BroadcastReceiver requestReciever = new BroadcastReceiver(){

        public void onReceive(Context context, Intent intent) {
            if (intent == null) {
                return;
            }
            String action = intent.getAction();

            if(BluetoothDevice.ACTION_FOUND.equals(action)){
                Log.d("BT", "Device Found");
                BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
                if(device!=null){
                    if(device.getName() != null && device.getName().length() > 0){
                        deviceArrayList.add(device.getName()+"\n"+device.getAddress()+"\n"+device.getUuids()[0].getUuid());
                        deviceList.add(device);
                    }
                }
            }
        };
    };


    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        // TODO Auto-generated method stub
        super.onActivityResult(requestCode, resultCode, data);

        if(requestCode == REQUEST_ENABLE_BT){
            if(resultCode == Activity.RESULT_CANCELED){
                Toast.makeText(this, "Uesr Doesn't want to switch on Bluetooth!!!", Toast.LENGTH_LONG).show();
                return;
            }
        }
    }



    @Override
    protected void onDestroy() {
        // TODO Auto-generated method stub
        super.onDestroy();
        if(mBluetoothAdapter != null){
            mBluetoothAdapter.cancelDiscovery();
        }
        if(requestReciever!=null)
            unregisterReceiver(requestReciever);
        Toast.makeText(this, "Bluetooth App Stopped", Toast.LENGTH_LONG).show();
    }
}

解决方案

device.getUuids() - here you have a Null, that is why you have an error here. Check this variable beforе using it.

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