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Android Bluetooth for discover devices, method Broadcast receiver is never called

i have problem with this code everything works but when i press scan button nothing happens why is that, i'm sure this code is right i follow Bluetooth Android Developer tutorial, Upon debug, I found that the onReceive method of BroadcastReceiver is never called. However, Bluetooth is enabled. What am I missing?
package com.example.bluetoothmaccounter;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import android.annotation.SuppressLint;
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.media.MediaPlayer;
import android.os.Bundle;
import android.os.Vibrator;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity {
Button buttonON , buttonOFF, scanBt;
ListView deviceList;
ArrayList<String> arrayList = new ArrayList<String>();
ArrayAdapter<String> arrayAdapter;
BluetoothAdapter bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
int requestCodeForEnable = 1;
Intent btEnablingIntent;
Vibrator vibrator;
MediaPlayer mediaPlayer;
TextView textView2 ;
#Override
protected void onCreate (Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
buttonOFF = findViewById(R.id.bt_off);
buttonON = findViewById(R.id.bt_on);
scanBt = findViewById(R.id.bt_scan);
deviceList = findViewById(R.id.device_list);
btEnablingIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
vibrator = (Vibrator) getSystemService(VIBRATOR_SERVICE);
mediaPlayer = MediaPlayer.create(this, R.raw.alarm);
textView2 = findViewById(R.id.textView2);
// /////////////////// Enable bluetooth ///////////////////////
buttonON.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (bluetoothAdapter == null) {
Toast.makeText(getApplicationContext(), "this device not support bluetooth", Toast.LENGTH_SHORT).show();
} else {
if (!bluetoothAdapter.isEnabled()) {
startActivityForResult(btEnablingIntent, requestCodeForEnable);
}
}
}
});
// /////////////////// disable bluetooth ///////////////////////
buttonOFF.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (bluetoothAdapter.isEnabled()) {
bluetoothAdapter.disable();
Toast.makeText(getApplicationContext(), "bluetooth disable", Toast.LENGTH_SHORT).show();
}
}
});
// /////////////////// start scan ///////////////////////
scanBt.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
arrayList.clear();
if (!bluetoothAdapter.isEnabled()) {
Toast.makeText(getApplicationContext(), " bluetooth not Enabled", Toast.LENGTH_SHORT).show();
} else {
bluetoothAdapter.startDiscovery();
Toast.makeText(getApplicationContext(), "discover started", Toast.LENGTH_SHORT).show();
}
}
});
try {
IntentFilter intentFilter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
textView2.setText("befoore receiver");
registerReceiver(receiver, intentFilter);
arrayAdapter = new ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_list_item_1, arrayList);
deviceList.setAdapter(arrayAdapter);
} catch (Exception e) {
textView2.setText("exeption" + e.getMessage());
}
}
// Create a BroadcastReceiver for ACTION_FOUND.
private final BroadcastReceiver receiver = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
textView2.setText("on receive 1");
String action = intent.getAction();
if (BluetoothDevice.ACTION_FOUND.equals(action)) {
textView2.setText("found");
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
arrayList.add(device.getName() + device.getAddress());
String size = "size is " + arrayList.size();
textView2.setText(size);
arrayAdapter.notifyDataSetChanged();
if (arrayList.size() >= 1) {
Toast.makeText(getApplicationContext(), "There are :" + arrayList.size() + "person here ", Toast.LENGTH_LONG).show();
vibrator.vibrate(3 * 1000);
mediaPlayer.start();
}
//
}
}
};
#Override
protected void onDestroy () {
super.onDestroy();
// Don't forget to unregister the ACTION_FOUND receiver.
textView2.setText("destrrooooooy");
unregisterReceiver(receiver);
}
}

<uses-permission android:name="android.permission.BLUETOOTH_ADMIN"></uses-permission>
<uses-permission android:name="android.permission.BLUETOOTH"></uses-permission>
You need to add these two permissions in AndroidManifest.xml

List Paired Bluetooth Devices

i'm trying to create a simple app in which I have a button in the MainActivity and a ListView in the PairingList activity. I want the button to enable bluetooth and then list all the paired devices in the listview in the other activity. However, I get a runtime exception as soon as I've enabled BT after I clicked the button. So far this is my code:
MainActivity.java
package com.gmburg.android.bluetoothservice;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.Set;
public class MainActivity extends AppCompatActivity {
Button btOn;
BluetoothAdapter btAdapter;
int REQUEST_CODE = 1;
Set<BluetoothDevice> paired_devices;
String plist[];
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btOn = (Button) findViewById(R.id.btOn);
btOn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
btAdapter = BluetoothAdapter.getDefaultAdapter();
if (btAdapter == null) {
Toast.makeText(getBaseContext(), "Device has no bluetooth antenna", Toast.LENGTH_LONG).show();
} else {
if (!btAdapter.isEnabled()) {
Intent i = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(i, REQUEST_CODE);
}
}
}
});
}
public void onActivityResult(int requestcode, int resultcode, Intent data) {
if (requestcode == REQUEST_CODE) {
if (resultcode == RESULT_OK) {
Toast.makeText(getBaseContext(), "Bluetooth enabled", Toast.LENGTH_LONG).show();
paired_devices = btAdapter.getBondedDevices();
int count = paired_devices.size();
plist = new String[count];
int j = 0;
for(BluetoothDevice device : paired_devices){
plist[j] = device.getName();
j++;
}
}
Bundle btOn = new Bundle();
btOn.putStringArray("paires", plist);
Intent in = new Intent("pair_filter");
in.putExtras(btOn);
startActivity(in);
}
}
}
PairingList.java
package com.gmburg.android.bluetoothservice;
import android.app.Activity;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.ListView;
public class PairingList extends Activity {
ListView lview;
String[] pairs;
ArrayAdapter<String> adapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.pairinglist_layout);
lview = (ListView) findViewById(R.id.listviewid);
Bundle btOn = getIntent().getExtras();
pairs = btOn.getStringArray("pairs");
adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, pairs);
lview.setAdapter(adapter);
}
}
The logger gives me this:
java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=1, result=-1, data=null} to activity {com.gmburg.android.bluetoothservice/com.gmburg.android.bluetoothservice.MainActivity}: android.content.ActivityNotFoundException: No Activity found to handle Intent { act=pair_filter (has extras) }
All the help is appreciated!

You are getting below error
android.content.ActivityNotFoundException: No Activity found to handle Intent { act=pair_filter (has extras)
this is because the intent you are trying to start activity for is not handled by any available activity/app in the phone. try resolveActivity method to find if any activity will be able to handle this, then only call startActivity/ForResult from your application.
resolveActivity Method's docs

android error :ViewRootImpl$CalledFromWrongThreadException [closed]

Closed. This question needs debugging details. It is not currently accepting answers.
Edit the question to include desired behavior, a specific problem or error, and the shortest code necessary to reproduce the problem. This will help others answer the question.
Closed 7 years ago.
Improve this question
i know it has been asked before for a different program but I am still getting error given below for my program
Thread [Thread-15956] (Suspended (exception ViewRootImpl$CalledFromWrongThreadException))
Please HELP!!
This is my MainActivity class
package a.example.na;
import java.util.Scanner;
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.view.Menu;
import android.view.MenuItem;
import android.view.View;
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.Toast;
import android.widget.AdapterView.OnItemClickListener;
public class MainActivity extends Activity {
private static TextView inputtext;
private BluetoothAdapter myBluetoothAdapter;
private Set<BluetoothDevice> pairedDevices;
private ListView myListView;
private ArrayAdapter<String> BTArrayAdapter;
private BluetoothDevice mDevice;
private Button findBtn;
private String address;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
myBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if(myBluetoothAdapter == null) {
findBtn.setEnabled(false);
Toast.makeText(getApplicationContext(),"Your device does not support Bluetooth",
Toast.LENGTH_LONG).show();
} else {
inputtext = (TextView) findViewById(R.id.text);
findBtn = (Button)findViewById(R.id.search);
findBtn.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
find(v);
}
});
myListView = (ListView)findViewById(R.id.listView1);
// create the arrayAdapter that contains the BTDevices, and set it to the ListView
BTArrayAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1);
myListView.setAdapter(BTArrayAdapter);
myListView.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> adapterView, View v, int pos,
long arg3) {
// Add the name and address to an array adapter to show in a ListView
String i = (String) adapterView.getItemAtPosition(pos);
B b=new B(inputtext);
b.start();
Scanner scanner = new Scanner(i);
if(scanner.hasNextLine()) {
address =scanner.nextLine();
}
mDevice = myBluetoothAdapter.getRemoteDevice(address);
scanner.close();
}
});
}
}
final BroadcastReceiver bReceiver = new BroadcastReceiver() {
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);
// add the name and the MAC address of the object to the arrayAdapter
BTArrayAdapter.add( device.getAddress()+ "\n" +device.getName() );
BTArrayAdapter.notifyDataSetChanged();
}
}
};
public void find(View view) {
if (myBluetoothAdapter.isDiscovering()) {
// the button is pressed when it discovers, so cancel the discovery
myBluetoothAdapter.cancelDiscovery();
}
else {
BTArrayAdapter.clear();
myBluetoothAdapter.startDiscovery();
registerReceiver(bReceiver, new IntentFilter(BluetoothDevice.ACTION_FOUND));
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
#Override
protected void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
unregisterReceiver(bReceiver);
}
}
This is my separate Thread class
package com.bt;
import android.widget.TextView;
public class B extends Thread {
TextView inputtext;
public B(TextView x){
inputtext=x;
}
public void run(){
inputtext.setText("hero");
}
}

Your are touching the views(widgets) in the Non UI Thread.
public class B extends Thread {
TextView inputtext;
Activity activity;
public B(Activity activity, TextView x) {
inputtext = x;
this.activity = activity;
}
public void run() {
activity.runOnUiThread(new Runnable() {
#Override
public void run() {
inputtext.setText("hero");
}
});
}
}
While starting the Thread
B b=new B(MainActivity.this, inputtext);
b.start();

NullPointerException when I try to test the implemented Bluetooth feature

I am trying to create an application which activates and deactivates Bluetooth, finds the paired Bluetooth devices and scans for discovered Bluetooth devices. I added the permissions to the AndroidManifest.xml. And everything seems to be ok. However when I debug the app on the device(Samsung Galaxy tab 3 Lite) I get NullPointerException and the application crashes. Do you have an idea what might cause the problem? Please find below my code and the exception stack trace.
package dyankov.mylibraryrecommender.MainActivities.GUI;
import android.app.Activity;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import dyankov.mylibraryrecommender.R;
import android.os.Bundle;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.content.BroadcastReceiver;
import android.content.Context;
import java.util.Set;
import android.content.Intent;
import android.content.IntentFilter;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
public class AroundMeActivity extends Activity {
private static final int REQUEST_ENABLE_BT = 1;
private Button turnOn;
private Button offBtn;
private Button listBtn;
private Button findBtn;
private TextView text;
private BluetoothAdapter myBluetoothAdapter;
private Set<BluetoothDevice> pairedDevices;
private ListView myListView;
private ArrayAdapter<String> BTArrayAdapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// take an instance of BluetoothAdapter - Bluetooth radio
myBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if(myBluetoothAdapter == null) {
turnOn.setEnabled(false);
offBtn.setEnabled(false);
listBtn.setEnabled(false);
findBtn.setEnabled(false);
text.setText("Status: not supported");
Toast.makeText(getApplicationContext(),"Your device does not support Bluetooth",
Toast.LENGTH_LONG).show();
} else {
text = (TextView) findViewById(R.id.text);
turnOn = (Button)findViewById(R.id.turnOn);
turnOn.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
on(v);
}
});
offBtn = (Button)findViewById(R.id.turnOff);
offBtn.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
off(v);
}
});
listBtn = (Button)findViewById(R.id.paired);
listBtn.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
list(v);
}
});
findBtn = (Button)findViewById(R.id.search);
findBtn.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
find(v);
}
});
myListView = (ListView)findViewById(R.id.listView1);
// create the arrayAdapter that contains the BTDevices, and set it to the ListView
BTArrayAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1);
myListView.setAdapter(BTArrayAdapter);
}
}
public void on(View view){
if (!myBluetoothAdapter.isEnabled()) {
Intent turnOnIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(turnOnIntent, REQUEST_ENABLE_BT);
Toast.makeText(getApplicationContext(),"Bluetooth turned on" ,
Toast.LENGTH_LONG).show();
}
else{
Toast.makeText(getApplicationContext(),"Bluetooth is already on",
Toast.LENGTH_LONG).show();
}
}
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
// TODO Auto-generated method stub
if(requestCode == REQUEST_ENABLE_BT){
if(myBluetoothAdapter.isEnabled()) {
text.setText("Status: Enabled");
} else {
text.setText("Status: Disabled");
}
}
}
public void list(View view){
// get paired devices
pairedDevices = myBluetoothAdapter.getBondedDevices();
// put it's one to the adapter
for(BluetoothDevice device : pairedDevices)
BTArrayAdapter.add(device.getName()+ "\n" + device.getAddress());
Toast.makeText(getApplicationContext(),"Show Paired Devices",
Toast.LENGTH_SHORT).show();
}
final BroadcastReceiver bReceiver = new BroadcastReceiver() {
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);
// add the name and the MAC address of the object to the arrayAdapter
BTArrayAdapter.add(device.getName() + "\n" + device.getAddress());
BTArrayAdapter.notifyDataSetChanged();
}
}
};
public void find(View view) {
if (myBluetoothAdapter.isDiscovering()) {
// the button is pressed when it discovers, so cancel the discovery
myBluetoothAdapter.cancelDiscovery();
}
else {
BTArrayAdapter.clear();
myBluetoothAdapter.startDiscovery();
registerReceiver(bReceiver, new IntentFilter(BluetoothDevice.ACTION_FOUND));
}
}
public void off(View view){
myBluetoothAdapter.disable();
text.setText("Status: Disconnected");
Toast.makeText(getApplicationContext(),"Bluetooth turned off",
Toast.LENGTH_LONG).show();
}
#Override
protected void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
unregisterReceiver(bReceiver);
}
}
And here is my Logcat file:
Caused by: java.lang.NullPointerException
at dyankov.mylibraryrecommender.MainActivities.GUI.AroundMeActivity.onCreate(AroundMeActivity.java:60)
at android.app.Activity.performCreate(Activity.java:5326)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1097)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2225)
The code on line 60 is:
turnOn.setOnClickListener(new OnClickListener() { ... }
            

put turnOn = (Button)findViewById(R.id.turnOn) and all your Button object initialization before turnOn.setEnabled(false);

You try to use button before you set value for it.
Try this code:
text = (TextView) findViewById(R.id.text);
turnOn = (Button)findViewById(R.id.turnOn);
if(myBluetoothAdapter == null) {
turnOn.setEnabled(false);
offBtn.setEnabled(false);
listBtn.setEnabled(false);
findBtn.setEnabled(false);
text.setText("Status: not supported");
Toast.makeText(getApplicationContext(),"Your device does not support Bluetooth",
Toast.LENGTH_LONG).show();
} else {
turnOn.setOnClickListener(new OnClickListener() {

Android Bluetooth Discover and Show Devices

I want to create simple application in which i want to show bluetooth devices..but when i press the button, Application crashes..
in ActivityMain.java this method will go to next activity (Activity.java)..in which i am getting problem..Rest of buttons are working
ActivityMain.java
package com.example.bluetoothcheck5;
import java.util.Set;
import com.example.bluetoothcheck5.Activity2;
import android.os.Bundle;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.content.Context;
import android.content.Intent;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends Activity {
private static final int REQUEST_ENABLE_BT = 0;
private static final int REQUEST_DISCOVERABLE_BT = 0;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final TextView out=(TextView)findViewById(R.id.out);
final Button button = (Button) findViewById(R.id.button1);
final Button button1 = (Button) findViewById(R.id.button2);
final Button button2 = (Button) findViewById(R.id.button3);
final Button buttonSearch = (Button) findViewById(R.id.buttonSearch);
final BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if (mBluetoothAdapter == null) {
out.append("device not supported");
}
button.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
if (!mBluetoothAdapter.isEnabled()) {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
}
}
});
button1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View arg0) {
if (!mBluetoothAdapter.isDiscovering()) {
Context context = getApplicationContext();
CharSequence text = "MAKING YOUR DEVICE DISCOVERABLE";
int duration = Toast.LENGTH_SHORT;
Toast toast = Toast.makeText(context, text, duration);
toast.show();
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
startActivityForResult(enableBtIntent, REQUEST_DISCOVERABLE_BT);
}
}
});
button2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View arg0) {
mBluetoothAdapter.disable();
Context context = getApplicationContext();
CharSequence text = "TURNING_OFF BLUETOOTH";
Toast toast = Toast.makeText(context, text, Toast.LENGTH_LONG);
toast.show();
Set<BluetoothDevice> mPairedDevices = mBluetoothAdapter.getBondedDevices();
if (mPairedDevices.size() > 0)
{
for (BluetoothDevice mDevice : mPairedDevices)
{
Log.v("Title", "PairedDevices: " + mDevice.getName() + " " + mDevice.getAddress());
}
}
}
});
buttonSearch.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
Intent myIntent = new Intent(arg0.getContext(), Activity2.class);
// myIntent.setClass(MainActivity.this, Activity2.class);
// startActivityForResult(myIntent, REQUEST_PAIRED_DEVICE);
startActivity(myIntent);
}
});
}}
Activity2.java
package com.example.bluetoothcheck5;
import java.util.Set;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.AdapterView.OnItemClickListener;
import com.example.bluetoothcheck5.R;
import com.example.bluetoothcheck5.MainActivity;
public class Activity2 extends MainActivity {
protected static final String TAG = "TAG";
private BluetoothAdapter mBluetoothAdapter;
private ArrayAdapter<String> mPairedDevicesArrayAdapter;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_2);
mPairedDevicesArrayAdapter = new ArrayAdapter<String>(this, R.layout.activity_2);
ListView mPairedListView = (ListView) findViewById(R.id.listView1);
mPairedListView.setAdapter(mPairedDevicesArrayAdapter);
mPairedListView.setOnItemClickListener(mDeviceClickListener);
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
Set<BluetoothDevice> mPairedDevices = mBluetoothAdapter.getBondedDevices();
if (mPairedDevices.size() > 0)
{
findViewById(R.id.title_paired_devices).setVisibility(View.VISIBLE);
for (BluetoothDevice mDevice : mPairedDevices)
{
mPairedDevicesArrayAdapter.add(mDevice.getName() + "\n" + mDevice.getAddress());
}
}
else
{
String mNoDevices = getResources().getText(R.string.none_paired).toString();
mPairedDevicesArrayAdapter.add(mNoDevices);
}
}
private OnItemClickListener mDeviceClickListener = new OnItemClickListener()
{
public void onItemClick(AdapterView<?> mAdapterView, View mView, int mPosition, long mLong)
{
mBluetoothAdapter.cancelDiscovery();
String mDeviceInfo = ((TextView) mView).getText().toString();
String mDeviceAddress = mDeviceInfo.substring(mDeviceInfo.length() - 17);
Log.v(TAG, "Device_Address " + mDeviceAddress);
Bundle mBundle = new Bundle();
mBundle.putString("DeviceAddress", mDeviceAddress);
Intent mBackIntent = new Intent();
mBackIntent.putExtras(mBundle);
setResult(Activity.RESULT_OK, mBackIntent);
finish();
}
};
}

i made sample project to demonstrate bluetooth disovering, pair or unpair device. Find it here,
http://www.londatiga.net/it/programming/android/how-to-programmatically-scan-or-discover-android-bluetooth-device/