Android设备蓝牙配对2

Question

I want to pair to them on click. But My Apps is Crashed.

I have given permission Bluetooth.Please help me!

cause by error:

06-12 19:34:40.997: E/AndroidRuntime(4172): Caused by: java.lang.NullPointerException 06-12 19:34:40.997: E/AndroidRuntime(4172): at com.example.bluetooth_tutorialplspoint.MainActivity.getPairedDevices(MainActivity.java:158)

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    on = (Button) findViewById(R.id.btnON);
    off = (Button) findViewById(R.id.btnOFF);
    Visible = (Button) findViewById(R.id.btnVisible);
    list = (Button) findViewById(R.id.btnList);
    lv = (ListView) findViewById(R.id.listView1);
    arrayListpaired=new ArrayList<String>();
    getPairedDevices();
    listeamclik=new ListIteamClick();


    BA = BluetoothAdapter.getDefaultAdapter();

    on.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View arg0) {
            if (!BA.isEnabled()) {
                Intent turnOn = new Intent(
                        BluetoothAdapter.ACTION_REQUEST_ENABLE);
                startActivityForResult(turnOn, 0);
                Toast.makeText(getApplicationContext(), "Turned on",
                        Toast.LENGTH_LONG).show();

            } else {
                Toast.makeText(getApplicationContext(), "Already on",
                        Toast.LENGTH_LONG).show();
            }

        }
    });

    off.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {

            BA.disable();
            Toast.makeText(getApplicationContext(), "Turned off",
                    Toast.LENGTH_LONG).show();
        }
    });

    Visible.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {

            Intent getVisible = new Intent(
                    BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
            startActivityForResult(getVisible, 0);

        }
    });

    list.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            pairedDeives = BA.getBondedDevices();

            if (pairedDeives != null) {

                ArrayList list = new ArrayList();
                for (BluetoothDevice bt : pairedDeives) {
                    list.add(bt.getName());

                    arraylistBloothdevice.add(bt);

                    Toast.makeText(getApplicationContext(),
                            "Showing paired Devices", Toast.LENGTH_LONG)
                            .show();
                     adapter = new ArrayAdapter(
                            getApplicationContext(),
                            R.layout.custom_textview, list);
                    lv.setAdapter(adapter);

                }
            }
        }

    });


}


public class ListIteamClick implements OnItemClickListener{

    @Override
    public void onItemClick(AdapterView<?> parent, View view, int position,
            long id) {
        btDevice=arraylistBloothdevice.get(position);
        Boolean isBonded=false;
        try {
            isBonded=createBond(btDevice);
            if(isBonded){
                getPairedDevices();
                adapter.notifyDataSetChanged();
            }

        } catch (Exception e) {
            // TODO: handle exception
        }

    }

}



   public boolean createBond(BluetoothDevice btDevice)  
            throws Exception  
            { 
                Class class1 = Class.forName("android.bluetooth.BluetoothDevice");
                Method createBondMethod = class1.getMethod("createBond");  
                Boolean returnValue = (Boolean) createBondMethod.invoke(btDevice);  
                return returnValue.booleanValue();  
            }  


    private void getPairedDevices() {
        Set<BluetoothDevice> pairedDevice = BA.getBondedDevices();            
        if(pairedDevice.size()>0)
        {
            for(BluetoothDevice device : pairedDevice)
            {
                arrayListpaired.add(device.getName()+"\n"+device.getAddress());
                arraylistBloothdevice.add(device);
            }
        }
     adapter.notifyDataSetChanged();
    }

}

Answer 1

Pairing Bluetooth devices on click is unorthodox; Android takes care of it for you. Pairing a device is as simple as discovering it! According to Android's official API Guides :

To be paired means that two devices are aware of each other's existence, have a shared link-key that can be used for authentication, and are capable of establishing an encrypted connection with each other.

Unless you have some special (I mean reeeaaaly special) reason for doing so, there is no need to manually pair devices because it's done automatically through discoverability.