Android + Pair devices via bluetooth programmatically

Question

I want to discover bluetooth devices in range, list and pair to them on click. I used following code but its just closing application when I click on device name which I want to pair.

I want to know mistake in my code or any other way to do what i need.

package com.marakana;      import java.util.Set;      import android.app.Activity;     import android.bluetooth.BluetoothAdapter;     import android.bluetooth.BluetoothDevice;     import android.content.BroadcastReceiver;     import android.content.Context;     import android.content.Intent;     import android.content.IntentFilter;     import android.os.Bundle;     import android.util.Log;     import android.view.View;     import android.view.Window;     import android.view.View.OnClickListener;     import android.widget.AdapterView;     import android.widget.ArrayAdapter;     import android.widget.Button;     import android.widget.ListView;     import android.widget.TextView;     import android.widget.AdapterView.OnItemClickListener;       public class BluetoothDemo extends Activity {     // Debugging     private static final String TAG = "DeviceListActivity";     private static final boolean D = true;      // Return Intent extra     public static String EXTRA_DEVICE_ADDRESS = "device_address";      // Member fields     private BluetoothAdapter mBtAdapter;     private ArrayAdapter<String> mPairedDevicesArrayAdapter;     private ArrayAdapter<String> mNewDevicesArrayAdapter;      @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);          // Setup the window         requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS);         setContentView(R.layout.device_list);          // Set result CANCELED incase the user backs out         setResult(Activity.RESULT_CANCELED);          // Initialize the button to perform device discovery         Button scanButton = (Button) findViewById(R.id.button_scan);         scanButton.setOnClickListener(new OnClickListener() {             public void onClick(View v) {                 doDiscovery();                 v.setVisibility(View.GONE);             }         });          // Initialize array adapters. One for already paired devices and         // one for newly discovered devices         mPairedDevicesArrayAdapter = new ArrayAdapter<String>(this, R.layout.device_name);         mNewDevicesArrayAdapter = new ArrayAdapter<String>(this, R.layout.device_name);          // Find and set up the ListView for paired devices         ListView pairedListView = (ListView) findViewById(R.id.paired_devices);         pairedListView.setAdapter(mPairedDevicesArrayAdapter);         pairedListView.setOnItemClickListener(mDeviceClickListener);          // Find and set up the ListView for newly discovered devices         ListView newDevicesListView = (ListView) findViewById(R.id.new_devices);         newDevicesListView.setAdapter(mNewDevicesArrayAdapter);         newDevicesListView.setOnItemClickListener(mDeviceClickListener);          // Register for broadcasts when a device is discovered         IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);         this.registerReceiver(mReceiver, filter);          // Register for broadcasts when discovery has finished         filter = new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);         this.registerReceiver(mReceiver, filter);          // Get the local Bluetooth adapter         mBtAdapter = BluetoothAdapter.getDefaultAdapter();          // Get a set of currently paired devices         Set<BluetoothDevice> pairedDevices = mBtAdapter.getBondedDevices();          // If there are paired devices, add each one to the ArrayAdapter         if (pairedDevices.size() > 0) {             findViewById(R.id.title_paired_devices).setVisibility(View.VISIBLE);             for (BluetoothDevice device : pairedDevices) {                 mPairedDevicesArrayAdapter.add(device.getName() + "\n" + device.getAddress());             }         } else {             String noDevices = getResources().getText(R.string.none_paired).toString();             mPairedDevicesArrayAdapter.add(noDevices);         }     }      @Override     protected void onDestroy() {         super.onDestroy();          // Make sure we're not doing discovery anymore         if (mBtAdapter != null) {             mBtAdapter.cancelDiscovery();         }          // Unregister broadcast listeners         this.unregisterReceiver(mReceiver);     }      /**      * Start device discover with the BluetoothAdapter      */     private void doDiscovery() {         if (D) Log.d(TAG, "doDiscovery()");          // Indicate scanning in the title         setProgressBarIndeterminateVisibility(true);         setTitle(R.string.scanning);          // Turn on sub-title for new devices         findViewById(R.id.title_new_devices).setVisibility(View.VISIBLE);          // If we're already discovering, stop it         if (mBtAdapter.isDiscovering()) {             mBtAdapter.cancelDiscovery();         }          // Request discover from BluetoothAdapter         mBtAdapter.startDiscovery();     }      // The on-click listener for all devices in the ListViews     private OnItemClickListener mDeviceClickListener = new 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 intent = new Intent();             intent.putExtra(EXTRA_DEVICE_ADDRESS, address);              // Set result and finish this Activity             setResult(Activity.RESULT_OK, intent);             finish();         }     };      // The BroadcastReceiver that listens for discovered devices and     // changes the title when discovery is finished     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());                 }             // When discovery is finished, change the Activity title             } else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) {                 setProgressBarIndeterminateVisibility(false);                 setTitle(R.string.select_device);                 if (mNewDevicesArrayAdapter.getCount() == 0) {                     String noDevices = getResources().getText(R.string.none_found).toString();                     mNewDevicesArrayAdapter.add(noDevices);                 }             }         }     }; } 

Answer 1

In my first answer the logic is shown for those who want to go with the logic only.

I think I was not able to make clear to @chalukya3545, that's why I am adding the whole code to let him know the exact flow of the code.

BluetoothDemo.java

public class BluetoothDemo extends Activity {      ListView listViewPaired;     ListView listViewDetected;     ArrayList<String> arrayListpaired;     Button buttonSearch,buttonOn,buttonDesc,buttonOff;     ArrayAdapter<String> adapter,detectedAdapter;     static HandleSeacrh handleSeacrh;     BluetoothDevice bdDevice;     BluetoothClass bdClass;     ArrayList<BluetoothDevice> arrayListPairedBluetoothDevices;     private ButtonClicked clicked;     ListItemClickedonPaired listItemClickedonPaired;     BluetoothAdapter bluetoothAdapter = null;     ArrayList<BluetoothDevice> arrayListBluetoothDevices = null;     ListItemClicked listItemClicked;      @Override      public void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.main);         listViewDetected = (ListView) findViewById(R.id.listViewDetected);         listViewPaired = (ListView) findViewById(R.id.listViewPaired);         buttonSearch = (Button) findViewById(R.id.buttonSearch);         buttonOn = (Button) findViewById(R.id.buttonOn);         buttonDesc = (Button) findViewById(R.id.buttonDesc);         buttonOff = (Button) findViewById(R.id.buttonOff);          arrayListpaired = new ArrayList<String>();         bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();         clicked = new ButtonClicked();         handleSeacrh = new HandleSeacrh();         arrayListPairedBluetoothDevices = new ArrayList<BluetoothDevice>();         /*          * the above declaration is just for getting the paired bluetooth devices;          * this helps in the removing the bond between paired devices.          */         listItemClickedonPaired = new ListItemClickedonPaired();         arrayListBluetoothDevices = new ArrayList<BluetoothDevice>();         adapter= new ArrayAdapter<String>(BluetoothDemo.this, android.R.layout.simple_list_item_1, arrayListpaired);         detectedAdapter = new ArrayAdapter<String>(BluetoothDemo.this, android.R.layout.simple_list_item_single_choice);         listViewDetected.setAdapter(detectedAdapter);         listItemClicked = new ListItemClicked();         detectedAdapter.notifyDataSetChanged();         listViewPaired.setAdapter(adapter);     }      @Override     protected void onStart() {         // TODO Auto-generated method stub         super.onStart();         getPairedDevices();         buttonOn.setOnClickListener(clicked);         buttonSearch.setOnClickListener(clicked);         buttonDesc.setOnClickListener(clicked);         buttonOff.setOnClickListener(clicked);         listViewDetected.setOnItemClickListener(listItemClicked);         listViewPaired.setOnItemClickListener(listItemClickedonPaired);     }     private void getPairedDevices() {         Set<BluetoothDevice> pairedDevice = bluetoothAdapter.getBondedDevices();                     if(pairedDevice.size()>0)         {             for(BluetoothDevice device : pairedDevice)             {                 arrayListpaired.add(device.getName()+"\n"+device.getAddress());                 arrayListPairedBluetoothDevices.add(device);             }         }         adapter.notifyDataSetChanged();     }     class ListItemClicked implements OnItemClickListener     {         @Override         public void onItemClick(AdapterView<?> parent, View view, int position, long id) {             // TODO Auto-generated method stub             bdDevice = arrayListBluetoothDevices.get(position);             //bdClass = arrayListBluetoothDevices.get(position);             Log.i("Log", "The dvice : "+bdDevice.toString());             /*              * here below we can do pairing without calling the callthread(), we can directly call the              * connect(). but for the safer side we must usethe threading object.              */             //callThread();             //connect(bdDevice);             Boolean isBonded = false;             try {                 isBonded = createBond(bdDevice);                 if(isBonded)                 {                     //arrayListpaired.add(bdDevice.getName()+"\n"+bdDevice.getAddress());                     //adapter.notifyDataSetChanged();                     getPairedDevices();                     adapter.notifyDataSetChanged();                 }             } catch (Exception e) {                 e.printStackTrace();              }//connect(bdDevice);             Log.i("Log", "The bond is created: "+isBonded);         }            }     class ListItemClickedonPaired implements OnItemClickListener     {         @Override         public void onItemClick(AdapterView<?> parent, View view, int position,long id) {             bdDevice = arrayListPairedBluetoothDevices.get(position);             try {                 Boolean removeBonding = removeBond(bdDevice);                 if(removeBonding)                 {                     arrayListpaired.remove(position);                     adapter.notifyDataSetChanged();                 }                   Log.i("Log", "Removed"+removeBonding);             } catch (Exception e) {                 // TODO Auto-generated catch block                 e.printStackTrace();             }         }     }     /*private void callThread() {         new Thread(){             public void run() {                 Boolean isBonded = false;                 try {                     isBonded = createBond(bdDevice);                     if(isBonded)                     {                         arrayListpaired.add(bdDevice.getName()+"\n"+bdDevice.getAddress());                         adapter.notifyDataSetChanged();                     }                 } catch (Exception e) {                     // TODO Auto-generated catch block                     e.printStackTrace();                  }//connect(bdDevice);                 Log.i("Log", "The bond is created: "+isBonded);             }                    }.start();     }*/     private Boolean connect(BluetoothDevice bdDevice) {          Boolean bool = false;         try {             Log.i("Log", "service method is called ");             Class cl = Class.forName("android.bluetooth.BluetoothDevice");             Class[] par = {};             Method method = cl.getMethod("createBond", par);             Object[] args = {};             bool = (Boolean) method.invoke(bdDevice);//, args);// this invoke creates the detected devices paired.             //Log.i("Log", "This is: "+bool.booleanValue());             //Log.i("Log", "devicesss: "+bdDevice.getName());         } catch (Exception e) {             Log.i("Log", "Inside catch of serviceFromDevice Method");             e.printStackTrace();         }         return bool.booleanValue();     };       public boolean removeBond(BluetoothDevice btDevice)       throws Exception       {           Class btClass = Class.forName("android.bluetooth.BluetoothDevice");         Method removeBondMethod = btClass.getMethod("removeBond");           Boolean returnValue = (Boolean) removeBondMethod.invoke(btDevice);           return returnValue.booleanValue();       }       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();       }         class ButtonClicked implements OnClickListener     {         @Override         public void onClick(View view) {             switch (view.getId()) {             case R.id.buttonOn:                 onBluetooth();                 break;             case R.id.buttonSearch:                 arrayListBluetoothDevices.clear();                 startSearching();                 break;             case R.id.buttonDesc:                 makeDiscoverable();                 break;             case R.id.buttonOff:                 offBluetooth();                 break;             default:                 break;             }         }     }     private BroadcastReceiver myReceiver = new BroadcastReceiver() {         @Override         public void onReceive(Context context, Intent intent) {             Message msg = Message.obtain();             String action = intent.getAction();             if(BluetoothDevice.ACTION_FOUND.equals(action)){                 Toast.makeText(context, "ACTION_FOUND", Toast.LENGTH_SHORT).show();                  BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);                 try                 {                     //device.getClass().getMethod("setPairingConfirmation", boolean.class).invoke(device, true);                     //device.getClass().getMethod("cancelPairingUserInput", boolean.class).invoke(device);                 }                 catch (Exception e) {                     Log.i("Log", "Inside the exception: ");                     e.printStackTrace();                 }                  if(arrayListBluetoothDevices.size()<1) // this checks if the size of bluetooth device is 0,then add the                 {                                           // device to the arraylist.                     detectedAdapter.add(device.getName()+"\n"+device.getAddress());                     arrayListBluetoothDevices.add(device);                     detectedAdapter.notifyDataSetChanged();                 }                 else                 {                     boolean flag = true;    // flag to indicate that particular device is already in the arlist or not                     for(int i = 0; i<arrayListBluetoothDevices.size();i++)                     {                         if(device.getAddress().equals(arrayListBluetoothDevices.get(i).getAddress()))                         {                             flag = false;                         }                     }                     if(flag == true)                     {                         detectedAdapter.add(device.getName()+"\n"+device.getAddress());                         arrayListBluetoothDevices.add(device);                         detectedAdapter.notifyDataSetChanged();                     }                 }             }                    }     };     private void startSearching() {         Log.i("Log", "in the start searching method");         IntentFilter intentFilter = new IntentFilter(BluetoothDevice.ACTION_FOUND);         BluetoothDemo.this.registerReceiver(myReceiver, intentFilter);         bluetoothAdapter.startDiscovery();     }     private void onBluetooth() {         if(!bluetoothAdapter.isEnabled())         {             bluetoothAdapter.enable();             Log.i("Log", "Bluetooth is Enabled");         }     }     private void offBluetooth() {         if(bluetoothAdapter.isEnabled())         {             bluetoothAdapter.disable();         }     }     private void makeDiscoverable() {         Intent discoverableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);         discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 300);         startActivity(discoverableIntent);         Log.i("Log", "Discoverable ");     }     class HandleSeacrh extends Handler     {         @Override         public void handleMessage(Message msg) {             switch (msg.what) {             case 111:                  break;              default:                 break;             }         }     } } 

Here is the main.xml

<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"     android:layout_width="fill_parent"     android:layout_height="fill_parent"     android:orientation="vertical" >      <Button          android:id="@+id/buttonOn"         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:text="On"/>     <Button          android:id="@+id/buttonDesc"         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:text="Make Discoverable"/>    <Button         android:id="@+id/buttonSearch"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="Search"/>    <Button         android:id="@+id/buttonOff"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="Bluetooth Off"/>     <ListView         android:id="@+id/listViewPaired"        android:layout_width="match_parent"        android:layout_height="120dp">     </ListView>     <ListView         android:id="@+id/listViewDetected"        android:layout_width="match_parent"        android:layout_height="match_parent">     </ListView> </LinearLayout> 

Add this permissions to your AndroidManifest.xml file:

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

The output for this code will look like this.

Answer 2

The Best way is do not use any pairing code. Instead of onClick go to other function or other class where You create the socket using UUID.
Android automatically pops up for pairing if already not paired.

or see this link for better understanding

Below is code for the same:

private OnItemClickListener mDeviceClickListener = new 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 intent = new Intent();         intent.putExtra(EXTRA_DEVICE_ADDRESS, address);          // Set result and finish this Activity         setResult(Activity.RESULT_OK, intent);        // **add this 2 line code**         Intent myIntent = new Intent(view.getContext(), Connect.class);         startActivityForResult(myIntent, 0);          finish();     } }; 

Connect.java file is :

public class Connect extends Activity { private static final String TAG = "zeoconnect"; private ByteBuffer localByteBuffer;  private InputStream in;  byte[] arrayOfByte = new byte[4096];  int bytes;     public BluetoothDevice mDevice;    @Override public void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.connect);                  try {                 setup();             } catch (ZeoMessageException e) {                 // TODO Auto-generated catch block                 e.printStackTrace();             } catch (ZeoMessageParseException e) {                 // TODO Auto-generated catch block                 e.printStackTrace();             }             }   private void setup() throws ZeoMessageException, ZeoMessageParseException  {     // TODO Auto-generated method stub          getApplicationContext().registerReceiver(receiver,                     new IntentFilter(BluetoothDevice.ACTION_ACL_CONNECTED));         getApplicationContext().registerReceiver(receiver,                     new IntentFilter(BluetoothDevice.ACTION_ACL_DISCONNECTED));              BluetoothDevice zee = BluetoothAdapter.getDefaultAdapter().                     getRemoteDevice("**:**:**:**:**:**");// add device mac adress              try {                 sock = zee.createRfcommSocketToServiceRecord(                          UUID.fromString("*******************")); // use unique UUID             } catch (IOException e1) {                 // TODO Auto-generated catch block                 e1.printStackTrace();             }              Log.d(TAG, "++++ Connecting");             try {                 sock.connect();             } catch (IOException e1) {                 // TODO Auto-generated catch block                 e1.printStackTrace();             }             Log.d(TAG, "++++ Connected");               try {                 in = sock.getInputStream();             } catch (IOException e1) {                 // TODO Auto-generated catch block                 e1.printStackTrace();             }                Log.d(TAG, "++++ Listening...");                while (true) {                    try {                       bytes = in.read(arrayOfByte);                       Log.d(TAG, "++++ Read "+ bytes +" bytes");                       } catch (IOException e1) {                         // TODO Auto-generated catch block                         e1.printStackTrace();                 }                         Log.d(TAG, "++++ Done: test()");                           }}       private static final LogBroadcastReceiver receiver = new LogBroadcastReceiver();     public static class LogBroadcastReceiver extends BroadcastReceiver {          @Override         public void onReceive(Context paramAnonymousContext, Intent paramAnonymousIntent) {             Log.d("ZeoReceiver", paramAnonymousIntent.toString());             Bundle extras = paramAnonymousIntent.getExtras();             for (String k : extras.keySet()) {                 Log.d("ZeoReceiver", "    Extra: "+ extras.get(k).toString());             }         }       };      private BluetoothSocket sock;     @Override     public void onDestroy() {         getApplicationContext().unregisterReceiver(receiver);         if (sock != null) {             try {                 sock.close();             } catch (IOException e) {                 e.printStackTrace();             }         }         super.onDestroy();     }  }