Develop Reference

How to access a button from an Activity in a fragment?

So I'm in a bit of a dilemma here,
I have a button in my DashboardFragment which can only be referenced within that class, and I need that button to enable bluetooth, which is done in a separate activity. I'd prefer not to have the Bluetooth code in my fragment class since the bluetooth will be referenced from multiple fragments. The issue is when I try to reference the Activity button from the Fragment class, I get a null object reference.
Here is my DashboardFragment class:
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
public View onCreateView(#NonNull LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
View root = inflater.inflate(R.layout.fragment_dashboard, container, false);
return root;
}
#Override
public void onViewCreated(View view, #Nullable Bundle savedInstanceState) {
connButton = (Button) getView().findViewById(R.id.button2);
connectionActivity = new ConnectionActivity();
connectionActivity.initView(connButton);
}
And my activity:
public class ConnectionActivity extends AppCompatActivity {
private static final String TAG = ConnectionActivity.class.getSimpleName();
BluetoothAdapter mBluetoothAdapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
public final BroadcastReceiver mBroadcastReceiver1 = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
final String action = intent.getAction();
if (action.equals(mBluetoothAdapter.ACTION_STATE_CHANGED)) {
final int state = intent.getIntExtra(BluetoothAdapter.EXTRA_STATE,
mBluetoothAdapter.ERROR);
//Use for when implementing states
switch (state) {
case BluetoothAdapter.STATE_OFF:
/*MainActivity.MyArrayAdapter adapter = (MainActivity.MyArrayAdapter) deviceSpinner.getAdapter();
if (adapter != null) {
adapter.clear();
adapter.notifyDataSetChanged();
}*/
Log.d(TAG, "STATE OFF");
break;
case BluetoothAdapter.STATE_TURNING_OFF:
Log.d(TAG,"STATE TURNING OFF");
break;
case BluetoothAdapter.STATE_ON:
//populateDeviceSpinner();
Log.d(TAG,"I'm ON!");
break;
case BluetoothAdapter.STATE_TURNING_ON:
Log.d(TAG,"Turning On...");
}
}
}
};
public void initView(Button connButton) {
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
connButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
enableDisableBT();
}
});
}
public void enableDisableBT() {
if (mBluetoothAdapter == null) {
Log.d(TAG, "Device does not have BLuetooth capabilites");
}
if (!mBluetoothAdapter.isEnabled()) {
Intent enableBTIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivity(enableBTIntent);
IntentFilter filter = new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED);
registerReceiver(mBroadcastReceiver1, filter);
}
if (mBluetoothAdapter.isEnabled()) {
mBluetoothAdapter.disable();
IntentFilter filter = new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED);
registerReceiver(mBroadcastReceiver1, filter);
}
}
}

Just add the reference in onViewCreated of DashboardFragment to
((ConnectionActivity) getActivity()).initView(connButton)

My Broadcastreceiver seem to detect that a call ended, still doesn't do that it should do. Does anybody see the flaws in my code?

I would like to make two calls in a row in an android app. Upon clicking button the app calls the first number. I created the broadcastreceiver below, that detects when the first call ends. It should write out that "First call ended" and then call the second number. It does not seem working. Can anybody spot the mistake in my code?
public class MainActivity extends AppCompatActivity {
public void calling(String phone) {
Intent callIntent = new Intent(Intent.ACTION_CALL)
.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
callIntent.setData(Uri.parse("tel:" + phone));
callIntent.putExtra("com.android.phone.extra.slot", 1);
startActivity(callIntent);
Intent intent = new Intent(this, CallReciever.class);
PendingIntent pendingIntent = PendingIntent.getBroadcast(this.getApplicationContext(), 234324243 , intent, 0);
startActivity(callIntent);
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button b = (Button) this.findViewById(R.id.CallButton);
b.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
calling("+36309577686");
}
});
}
public class CallReciever extends BroadcastReceiver {
private Context mContext;
private CustomPhoneStateListener mPhoneListener;
private String incoming_nr;
private int prev_state;
#Override
public void onReceive(Context context, Intent intent) {
mContext = context;
if (mPhoneListener == null) {
mPhoneListener = new CustomPhoneStateListener();
// TelephonyManager object
TelephonyManager telephony = (TelephonyManager) context.getSystemService(Context.TELEPHONY_SERVICE);
// Register our listener with TelephonyManager
telephony.listen(mPhoneListener, PhoneStateListener.LISTEN_CALL_STATE);
}
}
/* Custom PhoneStateListener */
class CustomPhoneStateListener extends PhoneStateListener {
#Override
public void onCallStateChanged(int state, String incomingNumber) {
if (!TextUtils.isEmpty(incomingNumber)) {
incoming_nr = incomingNumber;
}
switch (state) {
case TelephonyManager.CALL_STATE_RINGING:
prev_state = state;
break;
case TelephonyManager.CALL_STATE_OFFHOOK:
prev_state = state;
break;
case TelephonyManager.CALL_STATE_IDLE:
if ((prev_state == TelephonyManager.CALL_STATE_OFFHOOK)) {
// A call has now ended
//it writes out the call end, but does not call. why?
Toast.makeText(mContext, "Call End", Toast.LENGTH_SHORT).show();
calling("+36303853440");
prev_state = state;
}
else if ((prev_state == TelephonyManager.CALL_STATE_RINGING)) {
// Rejected or Missed call
Toast.makeText(mContext, "Rejected Call", Toast.LENGTH_SHORT).show();
prev_state = state;
}
break;
}
}
}
}
}

You are not registering the CallReciever anywhere. Try this
Button b = (Button) this.findViewById(R.id.CallButton);
b.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
calling("+36309577686");
registerReceiver(new CallReceiver());
}
});
Then unregister the receiver on broadcast is received

Android Wifi Direct onPeersAvailable doesn't shows anything

I'm trying to develop a simple app using Wifi Direct. The problem is I can't get a list of available peers using onPeersAvailable method. I tried the solutions mentioned here and here but no luck.There is nothing at logs, tried using Toast instead of log but nothing showed up on the screen either. Here is my Main and BroadCastReceiver classes.
Main Class:
public class MainActivity extends AppCompatActivity {
private final String TAG = this.getClass().toString();
WifiP2pManager mManager;
WifiP2pManager.Channel mChannel;
BroadcastReceiver mReceiver;
IntentFilter mIntentFilter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mManager = (WifiP2pManager) getSystemService(Context.WIFI_P2P_SERVICE);
mChannel = mManager.initialize(this, getMainLooper(), null);
mReceiver = new WiFiDirectBroadcastReceiver(mManager, mChannel, this);
mIntentFilter = new IntentFilter();
mIntentFilter.addAction(WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION);
mIntentFilter.addAction(WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION);
mIntentFilter.addAction(WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION);
mIntentFilter.addAction(WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION);
Button btn_discover = (Button) findViewById(R.id.btn_discover);
btn_discover.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
mManager.discoverPeers(mChannel, new WifiP2pManager.ActionListener() {
#Override
public void onSuccess() {
/*Toast.makeText(getApplicationContext(), "Discovery is a success.",
Toast.LENGTH_SHORT).show();*/
//startActivity(new Intent(Settings.ACTION_WIRELESS_SETTINGS));
}
#Override
public void onFailure(int reasonCode) {
Toast.makeText(getApplicationContext(), "Discovery is a failure "+reasonCode,
Toast.LENGTH_SHORT).show();
}
});
}
});
}
/* register the broadcast receiver with the intent values to be matched */
#Override
protected void onResume() {
super.onResume();
registerReceiver(mReceiver, mIntentFilter);
}
/* unregister the broadcast receiver */
#Override
protected void onPause() {
super.onPause();
unregisterReceiver(mReceiver);
}}
BroadCastReceiver class:
public class WiFiDirectBroadcastReceiver extends BroadcastReceiver {
private final String LOG_TAG = this.toString();
private WifiP2pManager mManager;
private WifiP2pManager.Channel mChannel;
private MainActivity mActivity;
public WiFiDirectBroadcastReceiver(WifiP2pManager manager, WifiP2pManager.Channel channel,
MainActivity activity) {
super();
this.mManager = manager;
this.mChannel = channel;
this.mActivity = activity;
}
#Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION.equals(action)) {
int state = intent.getIntExtra(WifiP2pManager.EXTRA_WIFI_STATE, -1);
if (state == WifiP2pManager.WIFI_P2P_STATE_ENABLED) {
Log.i(LOG_TAG, "Wifi Direct is enabled");
} else {
Log.i(LOG_TAG, "Wifi Direct is not enabled");
}
} else if (WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION.equals(action)) {
// request available peers from the wifi p2p manager. This is an
// asynchronous call and the calling activity is notified with a
// callback on PeerListListener.onPeersAvailable()
if (mManager != null) {
mManager.requestPeers(mChannel, new WifiP2pManager.PeerListListener() {
#Override
public void onPeersAvailable(WifiP2pDeviceList wifiP2pDeviceList) {
Log.i(LOG_TAG, "Found some peers!!! "+wifiP2pDeviceList.getDeviceList().size());
}
});
}
} else if (WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION.equals(action)) {
// Respond to new connection or disconnections
} else if (WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION.equals(action)) {
// Respond to this device's wifi state changing
}
}}
I am sure my device (2012 Nexus 7 running Android 4.4.4) supports Wifi Direct.

I think the issue is because you are creating new "PeerListListener" inside the "WiFiDirectBroadcastReceiver".
Try to add it to your main activity instead:
public class MainActivity extends AppCompatActivity implements WifiP2pManager.PeerListListener
And then add new method to you main activity to listen to available peers:
#Override
public void onPeersAvailable(WifiP2pDeviceList peerList) {
Log.i(LOG_TAG, "Found some peers!!! " + peerList.getDeviceList().size());
}
Note: Don't forget to create new listener variable instead "WiFiDirectBroadcastReceiver" and pass the main activity as a reference to it.
Hope this helps.

Android BLE Scan in Background Service

I'm trying to make an Android app that will scan for a certain Bluetooth device as a background service. Once the phone is within a certain range of the Bluetooth device, measured by reading the RSSI, the background service will start an Activity displayed to the user. If the phone is moved out of range of the Bluetooth device, (after the RSSI value is beyond a certain threshold,) the Activity should be killed.
Here is the code for the background service:
public class BeaconScanService extends Service implements BluetoothAdapter.LeScanCallback {
private Service self = this;
public static final String UNLOCK = "unlock";
public static final String STATUS = "status";
public static final String SIGNAL = "signal";
public static final String GET_SIGNAL = "get_signal";
//desired device to find
private static final String targetMAC = "E1:BE:A8:1A:8B:A0";
//class to handle saving RSSI values and detecting Bluetooth proximity
private proxDetector proxy;
//boolean to determine if phone is in BT range
static boolean inProx = false;
private BluetoothAdapter mBluetoothAdapter;
#Override
public IBinder onBind(Intent intent) {
// TODO Auto-generated method stub
return null;
}
#Override
public void onCreate() {
super.onCreate();
//Proximity Detector
proxy = new proxDetector();
final BluetoothManager bluetoothManager =
(BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
mBluetoothAdapter = bluetoothManager.getAdapter();
}
#Override
public int onStartCommand(Intent intent, int flags, int startId){
/*
* We need to enforce that Bluetooth is first enabled, and take the
* user to settings to enable it if they have not done so.
*/
if (mBluetoothAdapter == null || !mBluetoothAdapter.isEnabled()) {
//Bluetooth is disabled
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
enableBtIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(enableBtIntent);
}
/*
* Check for Bluetooth LE Support. In production, our manifest entry will keep this
* from installing on these devices, but this will allow test devices or other
* sideloads to report whether or not the feature exists.
*/
if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) {
Toast.makeText(this, "No LE Support.", Toast.LENGTH_SHORT).show();
return START_STICKY;
}
//Begin scanning for LE devices
startScan();
return START_STICKY;
}
#Override
public void onDestroy() {
super.onDestroy();
//Cancel any scans in progress
mHandler.removeCallbacks(mStopRunnable);
mHandler.removeCallbacks(mStartRunnable);
mBluetoothAdapter.stopLeScan(this);
}
private Runnable mStopRunnable = new Runnable() {
#Override
public void run() {
stopScan();
}
};
private Runnable mStartRunnable = new Runnable() {
#Override
public void run() {
startScan();
}
};
private void startScan() {
Toast.makeText(this, "Scanning", Toast.LENGTH_SHORT).show();
//Scan for Bluetooth device with specified MAC
mBluetoothAdapter.startLeScan(this);
mHandler.postDelayed(mStopRunnable, 5000);
}
private void stopScan() {
Toast.makeText(this, "Not Scanning", Toast.LENGTH_SHORT).show();
mBluetoothAdapter.stopLeScan(this);
mHandler.postDelayed(mStartRunnable, 2500);
}
/* BluetoothAdapter.LeScanCallback */
#Override
public void onLeScan(BluetoothDevice device, int rssi, byte[] scanRecord) {
/*
* Create a new beacon and pass it up to the main thread
*/
Toast.makeText(self, "OnLeScan", Toast.LENGTH_SHORT).show();
BT_Beacon beacon = new BT_Beacon(device.getAddress(), rssi);
mHandler.sendMessage(Message.obtain(null, 0, beacon));
}
/*
* We have a Handler to process scan results on the main thread
*/
private Handler mHandler = new Handler() {
#Override
public void handleMessage(Message msg) {
Toast.makeText(self, "Handlering", Toast.LENGTH_SHORT).show();
BT_Beacon beacon = (BT_Beacon) msg.obj;
if(beacon.getAddress().equals(targetMAC)){//Only look for target device
Toast.makeText(self, String.format("%ddBm", beacon.getSignal()), Toast.LENGTH_SHORT).show();
//HANDLE PROXIMITY DETECTION
Intent i1 = new Intent(UNLOCK);
proxy.processProx(beacon.getSignal());
Intent i2 = new Intent(SIGNAL);
i2.putExtra(GET_SIGNAL, proxy.prox);
sendBroadcast(i2);
if(proxy.crossedLine()){
i1.putExtra(STATUS, 1);
sendBroadcast(i1);
inProx = true;
Intent i = new Intent(self,MyActivity.class);
i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(i);
}else{
i1.putExtra(STATUS, 0);
sendBroadcast(i1);
inProx = false;
}
}
}
};
}
Ultimately I want this background service to be started on boot, but for testing purposes, I am able to create or destroy this service from an Activity that should also display the RSSI value:
public class MainActivity extends Activity implements OnClickListener {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button btnScan = (Button) findViewById(R.id.btnScan);
Button btnUnscan = (Button) findViewById(R.id.btnUnscan);
btnScan.setOnClickListener(this);
btnUnscan.setOnClickListener(this);
}
#Override
protected void onResume() {
super.onResume();
registerReceiver(mReceiver, new IntentFilter(BeaconScanService.SIGNAL));
}
#Override
protected void onPause() {
super.onPause();
unregisterReceiver(mReceiver);
}
#Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.btnScan:
Intent i = new Intent(this,BeaconScanService.class);
startService(i);
break;
case R.id.btnUnscan:
Intent i = new Intent(this,BeaconScanService.class);
stopService(i);
break;
}
}
private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
Bundle bundle = intent.getExtras();
if(bundle != null) {
int sig = bundle.getInt(BeaconScanService.GET_SIGNAL);
TextView rssiView = (TextView) findViewById(R.id.text_rssi);
rssiView.setText(String.format("%ddBm", sig));
}
}
};
}
This is the layout for for MainActivity:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
android:paddingBottom="#dimen/activity_vertical_margin"
tools:context=".MainActivity">
<Button
android:id="#+id/btnScan"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Scan"/>
<Button
android:id="#+id/btnUnscan"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Stop Scan"
android:layout_below="#+id/btnScan"/>
<TextView
android:id="#+id/text_rssi"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1"
android:textAppearance="?android:attr/textAppearanceListItem"
android:text="dBm"
android:layout_below="#+id/btnUnscan"/>
</RelativeLayout>
in the activity that is started and ended by the BeaconScanService, the BroadcastReceiver is registered like this:
#Override
protected void onResume() {
super.onResume();
registerReceiver(beaconScanReceiver, new IntentFilter(BeaconScanService.UNLOCK));
}
and the BroadcastReceiver looks like this:
private final BroadcastReceiver beaconScanReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
Bundle bundle = intent.getExtras();
if(bundle != null) {
int status = bundle.getInt(BeaconScanService.STATUS);
if(status == 0) {
finish();
}
}
}
};
When I run this code, I can start and stop the BeaconScanService fine, and I know the service is scanning for the Bluetooth device due to debug Toasts being displayed. As far as I can tell, the code breaks down somewhere in the Handler of the service. No RSSI value is displayed in the TextView, and MyActivity is not started when the phone is brought close enough to the Bluetooth device.
I'm not too familiar with the interprocess communication aspects of Android programming, so I'm probably doing something wrong there. Any thoughts?

Android Getting continuously Bluetooth signal strength of paired devices

i am listing all paired devices,and it well work but now want to get Bluetooth signal strength of paired devices...i know it will get by use rssi but cannot implement get it continuously in my app..
plz me by giving suitable code as my code...my code is here...
public class Security extends Fragment implements OnClickListener{
private BluetoothAdapter BA;
private Set<BluetoothDevice>pairedDevices;
ArrayList<String> mylist = new ArrayList<String>();
//private Object ImageView;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.security, null);
BA = BluetoothAdapter.getDefaultAdapter();
/* starting the bluetooth*/
on(v);
pairedDevices = BA.getBondedDevices();
//length=4;
// int j=1;
for(BluetoothDevice bt : pairedDevices) {
mylist.add(bt.getName());
length=j;
j++;
bt.getBondState();
}
return v;
}
#Override
public void onResume() {
super.onResume();
// Toast.makeText(getActivity(), "On resume", Toast.LENGTH_LONG).show();
}
/*************************Bluetooth function****************************/
public void on(View view){
if (!BA.isEnabled()) {
Intent turnOn = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(turnOn, 0);
Toast.makeText(getActivity(),"Turned on"
,Toast.LENGTH_LONG).show();
} else{
// Toast.makeText(getActivity(),"Already on",
// Toast.LENGTH_LONG).show();
}
}
public void Discovery(View view) {
if(BA.isDiscovering()) {
BA.cancelDiscovery();
}
}
public void list(View view){
Toast.makeText(getActivity(),"Showing Paired Devices",
Toast.LENGTH_SHORT).show();
}
#Override
public void onClick(View v) {
for(int j=0;j<length;j++) {
if(v.getId()==j)
Toast.makeText(getActivity(), mylist.get(j), Toast.LENGTH_LONG).show();
//hand.update(run,1000);
}
}
}

You can get the signal from following code.
Code your activity
#Override
public void onCreate(Bundle savedInstanceState) {
.....
// Registering Broadcast. this will fire when Bluetoothdevice Found
registerReceiver(receiver, new IntentFilter(BluetoothDevice.ACTION_ACL_CONNECTED));
}
private final BroadcastReceiver BroadcastReceiver = new BroadcastReceiver(){
#Override
public void onReceive(Context context, Intent intent) {
String mIntentAction = intent.getAction();
if(BluetoothDevice.ACTION_ACL_CONNECTED.equals(mIntentAction)) {
short rssi = intent.getShortExtra(BluetoothDevice.EXTRA_RSSI,Short.MIN_VALUE);
String mDeviceName = intent.getStringExtra(BluetoothDevice.EXTRA_NAME);
}
}
};
This broadcast will execute when your device will be connected to the remote device.
There are several other action on which you can fire this broadcast. have a look at here(BluetoothDevice)
Check following link for constant reading of RSSI
Tutorial to continuously measure the Bluetooth RSSI of a connected Android device (Java)
Output of link :

Then if you want to do it in continuously, you need to run it in a service or in a thread. So that you can even add time slots or sleep (waits) measuring the RSSI.