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How to show custom UI / widget on Lock Screen in Android

I have a requirement to show a customised screen over/on the lock screen in android. logically I want to show a screen (an activity) when phone is locked.
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I have tried multiple ways to achieve this functionality but no luck yet.
some links which I have followed are :
https://github.com/ShakeebM/Android-LockScreen
Create custom lockscreen for android 4.0 or above?
show web site on Android lock screen
Creating custom LockScreen in android
https://github.com/Kirk-Str/LockScreenApp
As of now I am able to show a custom screen over the lock screen when app is in foreground state but when app is in background/killed state not able to show the custom screen over the lock screen. Please suggest me what I am missing in my code snippet.
Manifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.lockscreen">
<uses-permission android:name="android.permission.DISABLE_KEYGUARD" />
<uses-permission android:name="android.permission.WAKE_LOCK" />
<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
<uses-permission android:name="android.permission.READ_PHONE_STATE" />
<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />
<uses-permission android:name="android.permission.FOREGROUND_SERVICE"/>
<application
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:roundIcon="#mipmap/ic_launcher_round">
<activity
android:name=".sample2.screen.LockScreenActivity"
android:excludeFromRecents="true"
android:label="#string/app_name"
android:launchMode="singleTask"
android:screenOrientation="portrait"
android:theme="#android:style/Theme.NoTitleBar.Fullscreen"
android:showOnLockScreen="true"
android:turnScreenOn="false"
android:noHistory="true"
android:exported="true">
<intent-filter >
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<service android:name=".sample2.utils.LockscreenService" >
</service>
<receiver
android:name=".sample2.utils.LockscreenIntentReceiver"
android:enabled="true"
android:exported="false">
<intent-filter>
<action android:name="android.intent.action.BOOT_COMPLETED" />
</intent-filter>
</receiver>
</application>
</manifest>
LockscreenService Class:
package com.example.lockscreen.sample2.utils;
import android.app.Notification;
import android.app.Service;
import android.content.BroadcastReceiver;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.IBinder;
import android.util.Log;
import androidx.core.app.NotificationCompat;
import com.example.lockscreen.R;
public class LockscreenService extends Service {
private BroadcastReceiver mReceiver;
#Override
public IBinder onBind(Intent intent) {
return null;
}
#Override
public void onCreate() {
super.onCreate();
}
// Register for Lockscreen event intents
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.e("LockScreen ::: ","onStartCommand");
IntentFilter filter = new IntentFilter(Intent.ACTION_SCREEN_ON);
filter.addAction(Intent.ACTION_SCREEN_OFF);
mReceiver = new LockscreenIntentReceiver();
registerReceiver(mReceiver, filter);
startForeground();
return START_STICKY;
}
// Run service in foreground so it is less likely to be killed by system
private void startForeground() {
Notification notification = new NotificationCompat.Builder(this)
.setContentTitle(getResources().getString(R.string.app_name))
.setTicker(getResources().getString(R.string.app_name))
.setContentText("Running")
.setSmallIcon(R.drawable.ic_launcher_foreground)
.setContentIntent(null)
.setOngoing(true)
.build();
startForeground(9999,notification);
}
// Unregister receiver
#Override
public void onDestroy() {
super.onDestroy();
unregisterReceiver(mReceiver);
}
}
LockscreenIntentReceiver Class:
package com.example.lockscreen.sample2.utils;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import com.example.lockscreen.sample2.screen.LockScreenActivity;
public class LockscreenIntentReceiver extends BroadcastReceiver {
// Handle actions and display Lockscreen
#Override
public void onReceive(Context context, Intent intent) {
if (intent.getAction().equals(Intent.ACTION_SCREEN_OFF)
|| intent.getAction().equals(Intent.ACTION_SCREEN_ON)
|| intent.getAction().equals(Intent.ACTION_BOOT_COMPLETED)) {
start_lockscreen(context);
}
}
// Display lock screen
private void start_lockscreen(Context context) {
Intent mIntent = new Intent(context, LockScreenActivity.class);
mIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
context.startActivity(mIntent);
}
}
LockScreenActivity Class:
package com.example.lockscreen.sample2.screen;
import android.app.Activity;
import android.app.KeyguardManager;
import android.content.Intent;
import android.os.Bundle;
import android.telephony.PhoneStateListener;
import android.telephony.TelephonyManager;
import android.view.KeyEvent;
import android.view.View;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.Toast;
import com.example.lockscreen.R;
import com.example.lockscreen.sample2.utils.LockscreenService;
import com.example.lockscreen.sample2.utils.LockscreenUtils;
public class LockScreenActivity extends Activity implements
LockscreenUtils.OnLockStatusChangedListener {
// User-interface
private Button btnUnlock;
// Member variables
private LockscreenUtils mLockscreenUtils;
// Set appropriate flags to make the screen appear over the keyguard
#Override
public void onAttachedToWindow() {
this.getWindow().addFlags(
WindowManager.LayoutParams.FLAG_FULLSCREEN
| WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED
| WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON
| WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD
);
super.onAttachedToWindow();
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.getWindow().addFlags(
WindowManager.LayoutParams.FLAG_FULLSCREEN
| WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED
| WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON
| WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD
);
setContentView(R.layout.activity_lockscreen);
init();
// unlock screen in case of app get killed by system
if (getIntent() != null && getIntent().hasExtra("kill")
&& getIntent().getExtras().getInt("kill") == 1) {
enableKeyguard();
unlockHomeButton();
}
try {
// disable keyguard
disableKeyguard();
// lock home button
lockHomeButton();
Toast.makeText(getApplicationContext(),"lockHomeButton startService", Toast.LENGTH_LONG).show();
// start service for observing intents
startService(new Intent(this, LockscreenService.class));
// listen the events get fired during the call
StateListener phoneStateListener = new StateListener();
TelephonyManager telephonyManager = (TelephonyManager) getSystemService(TELEPHONY_SERVICE);
telephonyManager.listen(phoneStateListener,
PhoneStateListener.LISTEN_CALL_STATE);
} catch (Exception e) {
}
}
private void init() {
mLockscreenUtils = new LockscreenUtils();
btnUnlock = (Button) findViewById(R.id.btnUnlock);
btnUnlock.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// unlock home button and then screen on button press
unlockHomeButton();
}
});
}
// Handle events of calls and unlock screen if necessary
private class StateListener extends PhoneStateListener {
#Override
public void onCallStateChanged(int state, String incomingNumber) {
super.onCallStateChanged(state, incomingNumber);
switch (state) {
case TelephonyManager.CALL_STATE_RINGING:
unlockHomeButton();
break;
case TelephonyManager.CALL_STATE_OFFHOOK:
break;
case TelephonyManager.CALL_STATE_IDLE:
break;
}
}
};
// Don't finish Activity on Back press
#Override
public void onBackPressed() {
return;
}
// Handle button clicks
#Override
public boolean onKeyDown(int keyCode, android.view.KeyEvent event) {
if ((keyCode == KeyEvent.KEYCODE_VOLUME_DOWN)
|| (keyCode == KeyEvent.KEYCODE_POWER)
|| (keyCode == KeyEvent.KEYCODE_VOLUME_UP)
|| (keyCode == KeyEvent.KEYCODE_CAMERA)) {
return true;
}
if ((keyCode == KeyEvent.KEYCODE_HOME)) {
return true;
}
return false;
}
// handle the key press events here itself
public boolean dispatchKeyEvent(KeyEvent event) {
if (event.getKeyCode() == KeyEvent.KEYCODE_VOLUME_UP
|| (event.getKeyCode() == KeyEvent.KEYCODE_VOLUME_DOWN)
|| (event.getKeyCode() == KeyEvent.KEYCODE_POWER)) {
return false;
}
if ((event.getKeyCode() == KeyEvent.KEYCODE_HOME)) {
return true;
}
return false;
}
// Lock home button
public void lockHomeButton() {
mLockscreenUtils.lock(LockScreenActivity.this);
}
// Unlock home button and wait for its callback
public void unlockHomeButton() {
mLockscreenUtils.unlock();
}
// Simply unlock device when home button is successfully unlocked
#Override
public void onLockStatusChanged(boolean isLocked) {
if (!isLocked) {
unlockDevice();
}
}
#Override
protected void onStop() {
super.onStop();
unlockHomeButton();
}
#SuppressWarnings("deprecation")
private void disableKeyguard() {
KeyguardManager mKM = (KeyguardManager) getSystemService(KEYGUARD_SERVICE);
KeyguardManager.KeyguardLock mKL = mKM.newKeyguardLock("IN");
mKL.disableKeyguard();
}
#SuppressWarnings("deprecation")
private void enableKeyguard() {
KeyguardManager mKM = (KeyguardManager) getSystemService(KEYGUARD_SERVICE);
KeyguardManager.KeyguardLock mKL = mKM.newKeyguardLock("IN");
mKL.reenableKeyguard();
}
//Simply unlock device by finishing the activity
private void unlockDevice()
{
finish();
}
}
Please help me how can I achieve this?

NFC Tag Reading Activity not receiving intent

I have an activity to read NFC Type A tags (non-NDEF). I am running Android Studio with Android phone in developer mode.
The project launches the application correctly on the developer Android phone with NFC switched on on the phone. When I tap my NFC contactless card on the phone, the phone detects the NFC card but shows an options list of other NFC reader application installed on the phone instead of passing the intent to the foreground application.
How do I get the foreground project's application to receive the NFC intent instead of having a suggestions list popout ?
Here's my AndroidManifest.xml file:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="testtag">
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:roundIcon="#mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<activity android:name=".TapTagActivity">
<intent-filter>
<action android:name="android.nfc.action.TECH_DISCOVERED" />
</intent-filter>
<meta-data
android:name="android.nfc.action.TECH_DISCOVERED"
android:resource="#xml/nfc_tech_filter" />
</activity>
<activity android:name=".ManageTagActivity"></activity>
<activity android:name=".EnquireTagActivity"></activity>
<activity android:name=".SelectTagActionActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".TestActivity" />
</application>
<uses-permission android:name="android.permission.NFC" />
<uses-sdk android:minSdkVersion="10" />
<uses-feature
android:name="android.hardware.nfc"
android:required="true" />
</manifest>
Here's the Activity Java class:
package testtag;
import androidx.appcompat.app.AppCompatActivity;
import android.app.Activity;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.nfc.NfcAdapter;
import android.nfc.NfcManager;
import android.nfc.Tag;
import android.os.Bundle;
import android.util.Log;
public class TapTagActivity extends AppCompatActivity {
private static Class targetActivity = null;
private NfcAdapter nfcAdapter = null;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_tap_tag);
System.out.println("Tap Tag window ready ...");
NfcManager nfcManager = (NfcManager) getSystemService(Context.NFC_SERVICE);
// nfcAdapter = nfcManager.getDefaultAdapter();
nfcAdapter = NfcAdapter.getDefaultAdapter(this);
if (nfcManager != null) {
System.out.println("NFC Manager ready ...");
}
if (nfcAdapter != null) {
System.out.println("NFC Adapter ready ...");
}
}
#Override
protected void onResume() {
super.onResume();
Intent intent = new Intent();
intent.addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);
PendingIntent nfcPendingIntent = PendingIntent.getActivity(this, 0, intent, 0);
if (nfcAdapter != null) {
nfcAdapter.enableForegroundDispatch(this, nfcPendingIntent, null, null);
}
}
#Override
protected void onPause() {
super.onPause();
if (nfcAdapter != null) {
try {
nfcAdapter.disableForegroundDispatch(this);
} catch (IllegalStateException ex) {
Log.e("ATHTAG","Error disabling NFC foreground dispatch", ex);
}
}
}
#Override
protected void onNewIntent(Intent intent) {
super.onNewIntent(intent);
System.out.println("Doing onNewIntent() ...");
// Use NFC to read tag
Tag tag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
if (tag != null) {
System.out.println("New tag found !!!");
} else {
System.out.println("No new tag found !!!");
}
}
public static void setTargetRedirectIntent(Class activity) {
targetActivity = activity;
}
}
The console manages to print the:
I/System.out: Tap Tag window ready ...
I/System.out: NFC Manager ready ...
NFC Adapter ready ...
How do I read the NFC card from the foreground without having the suggestions list with installed NFC reader apps appear ?

I figured out that I have to set enableForegroundDispatch() parameters in the onResume() instead of leaving null values.
Working code:
package testtag;
import androidx.appcompat.app.AppCompatActivity;
import android.app.Activity;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.nfc.NfcAdapter;
import android.nfc.NfcManager;
import android.nfc.Tag;
import android.nfc.tech.IsoDep;
import android.nfc.tech.NfcA;
import android.nfc.tech.NfcB;
import android.os.Bundle;
import android.util.Log;
public class TapTagActivity extends AppCompatActivity {
private static Class targetActivity = null;
private NfcAdapter nfcAdapter = null;
private IntentFilter[] intentFiltersArray = null;
private String[][] techListsArray = null;
private PendingIntent pendingIntent = null;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_tap_tag);
System.out.println("Tap Tag window ready ...");
NfcManager nfcManager = (NfcManager) getSystemService(Context.NFC_SERVICE);
// nfcAdapter = nfcManager.getDefaultAdapter();
nfcAdapter = NfcAdapter.getDefaultAdapter(this);
if (nfcManager != null) {
System.out.println("NFC Manager ready ...");
}
if (nfcAdapter != null) {
System.out.println("NFC Adapter ready ...");
}
pendingIntent = PendingIntent.getActivity(
this, 0, new Intent(this, getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);
intentFiltersArray = new IntentFilter[]{new IntentFilter(NfcAdapter.ACTION_TECH_DISCOVERED)};
techListsArray = new String[][]{new String[]{NfcA.class.getName()}, new String[]{NfcB.class.getName()}, new String[]{IsoDep.class.getName()}};
}
#Override
protected void onResume() {
super.onResume();
Intent intent = new Intent();
intent.addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);
PendingIntent nfcPendingIntent = PendingIntent.getActivity(this, 0, intent, 0);
if (nfcAdapter != null) {
nfcAdapter.enableForegroundDispatch(this, pendingIntent, intentFiltersArray, techListsArray);
}
}
#Override
protected void onPause() {
super.onPause();
if (nfcAdapter != null) {
try {
nfcAdapter.disableForegroundDispatch(this);
} catch (IllegalStateException ex) {
Log.e("ATHTAG", "Error disabling NFC foreground dispatch", ex);
}
}
}
#Override
protected void onNewIntent(Intent intent) {
super.onNewIntent(intent);
System.out.println("Doing onNewIntent() ...");
// Use NFC to read tag
Tag tag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
if (tag != null) {
System.out.println("New tag found !!!");
} else {
System.out.println("No new tag found !!!");
}
}
public static void setTargetRedirectIntent(Class activity) {
targetActivity = activity;
}
}

Why do I get ClassCastException when I extend a class?

I'm developing an app which can read data from a Bluetooth RFID Reader, but everytime i start the BluetoothActivity (it's a tabbed activity), it always shows a ClassCastException, below is my code..
BluetoothActivity class:
package com.siscaproject.sisca.Activity;
import android.net.Uri;
import android.support.annotation.Nullable;
import android.support.design.widget.Snackbar;
import android.support.design.widget.TabLayout;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import com.siscaproject.sisca.Fragment.RegisterFragment;
import com.siscaproject.sisca.Fragment.SearchFragment;
import com.siscaproject.sisca.R;
import com.siscaproject.sisca.Utilities.FamsModel;
import com.siscaproject.sisca.Utilities.TSLBluetoothDeviceActivity;
import com.siscaproject.sisca.Utilities.TSLBluetoothDeviceApplication;
import com.uk.tsl.rfid.asciiprotocol.AsciiCommander;
import com.uk.tsl.rfid.asciiprotocol.responders.LoggerResponder;
import java.util.ArrayList;
import butterknife.BindView;
import butterknife.ButterKnife;
public class BluetoothActivity extends TSLBluetoothDeviceActivity {
private SectionsPagerAdapter mSectionsPagerAdapter;
#BindView(R.id.viewpager_bluetooth) ViewPager mViewPager;
#BindView(R.id.toolbar_bluetooth) Toolbar mToolbar;
#BindView(R.id.tab_bluetooth) TabLayout mTabLayout;
private FamsModel mModel;
public AsciiCommander getCommander(){
return ((TSLBluetoothDeviceApplication) getApplication()).getCommander();
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_bluetooth);
ButterKnife.bind(this);
setSupportActionBar(mToolbar);
// Create the adapter that will return a fragment for each of the three
// primary sections of the activity.
mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
// Set up the ViewPager with the sections adapter.
setupViewPager(mViewPager);
mTabLayout.setupWithViewPager(mViewPager);
AsciiCommander commander = getCommander();
// Add the LoggerResponder - this simply echoes all lines received from the reader to the log
// and passes the line onto the next responder
// This is added first so that no other responder can consume received lines before they are logged.
commander.addResponder(new LoggerResponder());
// Add a synchronous responder to handle synchronous commands
commander.addSynchronousResponder();
}
private void setupViewPager(ViewPager viewPager){
SectionsPagerAdapter adapter = new SectionsPagerAdapter(getSupportFragmentManager());
adapter.addFragment(new RegisterFragment(), "REGISTER");
adapter.addFragment(new SearchFragment(), "SEARCH");
viewPager.setAdapter(adapter);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_bluetooth, 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();
//noinspection SimplifiableIfStatement
if (id == R.id.menu_item_reconnect_reader) {
return true;
}
return super.onOptionsItemSelected(item);
}
public static class PlaceholderFragment extends Fragment {
private static final String ARG_SECTION_NUMBER = "section_number";
public PlaceholderFragment() {
}
public static PlaceholderFragment newInstance(int sectionNumber) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_bluetooth, container, false);
TextView textView = (TextView) rootView.findViewById(R.id.section_label);
textView.setText(getString(R.string.section_format, getArguments().getInt(ARG_SECTION_NUMBER)));
return rootView;
}
}
public class SectionsPagerAdapter extends FragmentPagerAdapter {
private ArrayList<Fragment> fragmentList = new ArrayList<>();
private ArrayList<String> fragmentTitleList = new ArrayList<>();
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
return fragmentList.get(position);
}
#Override
public int getCount() {
// Show 3 total pages.
return fragmentList.size();
}
public void addFragment(Fragment fragment, String title ){
fragmentList.add(fragment);
fragmentTitleList.add(title);
}
#Nullable
#Override
public CharSequence getPageTitle(int position) {
return fragmentTitleList.get(position);
}
}
}
TSLBluetoothDeviceActivity class:
package com.siscaproject.sisca.Utilities;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.widget.Toast;
import com.siscaproject.sisca.BuildConfig;
import com.uk.tsl.rfid.DeviceListActivity;
import com.uk.tsl.rfid.asciiprotocol.AsciiCommander;
import java.util.Timer;
import java.util.TimerTask;
public class TSLBluetoothDeviceActivity extends AppCompatActivity {
// Debugging
private static final String TAG = "TSLBTDeviceActivity";
private static final boolean D = BuildConfig.DEBUG;
// Intent request codes
private static final int REQUEST_CONNECT_DEVICE_SECURE = 1;
private static final int REQUEST_CONNECT_DEVICE_INSECURE = 2;
private static final int REQUEST_ENABLE_BT = 3;
// Local Bluetooth adapter
private BluetoothAdapter mBluetoothAdapter = null;
private BluetoothDevice mDevice = null;
protected AsciiCommander getCommander() {
return ((TSLBluetoothDeviceApplication) getApplication()).getCommander();
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Get local Bluetooth adapter
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
// Create the AsciiCommander to talk to the reader (if it doesn't already exist)
if (getCommander() == null) {
try {
TSLBluetoothDeviceApplication app = (TSLBluetoothDeviceApplication) getApplication();
AsciiCommander commander = new AsciiCommander(getApplicationContext());
app.setCommander(commander);
} catch (Exception e) {
fatalError("Unable to create AsciiCommander!");
}
}
}
// Terminate the app with the given message
private void fatalError(String message) {
Toast.makeText(this, message, Toast.LENGTH_LONG).show();
Timer t = new Timer();
t.schedule(new TimerTask() {
public void run() {
finish();
}
}, 1800);
}
protected void bluetoothNotAvailableError(String message) {
fatalError(message);
}
#Override
public void onStart() {
super.onStart();
// If no other attempt to connect is ongoing try to connect to last used reader
// Note: When returning from the Device List activity
if (mBluetoothAdapter.isEnabled()) {
if (mDevice == null) {
// Attempt to reconnect to the last reader used
Toast.makeText(this, "Reconnecting to last used reader...", Toast.LENGTH_SHORT).show();
getCommander().connect(null);
}
} else {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
}
}
#Override
public void onStop() {
super.onStop();
getCommander().disconnect();
mDevice = null;
}
protected void connectToDevice(Intent deviceData, boolean secure) {
Toast.makeText(this.getApplicationContext(), "Connecting...", Toast.LENGTH_LONG).show();
// Get the device MAC address
String address = deviceData.getExtras()
.getString(DeviceListActivity.EXTRA_DEVICE_ADDRESS);
// Get the BluetoothDevice object
mDevice = mBluetoothAdapter.getRemoteDevice(address);
// Attempt to connect to the device
if (mDevice != null) {
getCommander().connect(mDevice);
} else {
if (D) Log.e(TAG, "Unable to obtain BluetoothDevice!");
}
}
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if (D)
Log.d(TAG, "selectDevice() onActivityResult: " + resultCode + " for request: " + requestCode);
switch (requestCode) {
case REQUEST_CONNECT_DEVICE_SECURE:
// When DeviceListActivity returns with a device to connect
if (resultCode == Activity.RESULT_OK) {
connectToDevice(data, true);
}
break;
case REQUEST_CONNECT_DEVICE_INSECURE:
// When DeviceListActivity returns with a device to connect
if (resultCode == Activity.RESULT_OK) {
connectToDevice(data, false);
}
break;
case REQUEST_ENABLE_BT:
// When the request to enable Bluetooth returns
if (resultCode != Activity.RESULT_OK) {
// User did not enable Bluetooth or an error occurred
Log.d(TAG, "BT not enabled");
bluetoothNotAvailableError("Bluetooth was not enabled\nApplication Quitting...");
}
}
}
public void selectDevice() {
// Launch the DeviceListActivity to see devices and do scan
Intent serverIntent = new Intent(this, DeviceListActivity.class);
startActivityForResult(serverIntent, REQUEST_CONNECT_DEVICE_INSECURE);
}
public void disconnectDevice() {
mDevice = null;
getCommander().disconnect();
}
public void reconnectDevice() {
getCommander().connect(null);
}
}
The error log:
11-21 14:47:54.836 18956-18956/com.siscaproject.sisca E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.siscaproject.sisca, PID: 18956
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.siscaproject.sisca/com.siscaproject.sisca.Activity.BluetoothActivity}: java.lang.ClassCastException: android.app.Application cannot be cast to com.siscaproject.sisca.Utilities.TSLBluetoothDeviceApplication
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2318)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2396)
at android.app.ActivityThread.access$800(ActivityThread.java:139)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1293)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:149)
at android.app.ActivityThread.main(ActivityThread.java:5257)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:609)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.ClassCastException: android.app.Application cannot be cast to com.siscaproject.sisca.Utilities.TSLBluetoothDeviceApplication
at com.siscaproject.sisca.Activity.BluetoothActivity.getCommander(BluetoothActivity.java:51)
at com.siscaproject.sisca.Utilities.TSLBluetoothDeviceActivity.onCreate(TSLBluetoothDeviceActivity.java:45)
at com.siscaproject.sisca.Activity.BluetoothActivity.onCreate(BluetoothActivity.java:57)
at android.app.Activity.performCreate(Activity.java:5411)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2270)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2396) 
at android.app.ActivityThread.access$800(ActivityThread.java:139) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1293) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:149) 
at android.app.ActivityThread.main(ActivityThread.java:5257) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:515) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:609) 
at dalvik.system.NativeStart.main(Native Method) 
I've followed this code from an app that works fine, but when I implemented it in my project it always shows this error, I'm not sure what I'm doing wrong.
---EDIT---
TSLBluetoothDeviceApplication class:
package com.siscaproject.sisca.Utilities;
import android.app.Application;
import com.uk.tsl.rfid.asciiprotocol.AsciiCommander;
public class TSLBluetoothDeviceApplication extends Application {
private static AsciiCommander commander = null;
/// Returns the current AsciiCommander
public AsciiCommander getCommander() {
return commander;
}
/// Sets the current AsciiCommander
public void setCommander(AsciiCommander _commander) {
commander = _commander;
}
}
Android Manifest:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
package="com.siscaproject.sisca">
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.BLUETOOTH_PRIVILEGED" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.VIBRATE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:roundIcon="#mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="#style/AppTheme"
tools:replace="android:icon">
<activity
android:name=".Activity.LoginActivity"
android:screenOrientation="portrait">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".Activity.BluetoothTestActivity"
android:theme="#style/StandardTheme" />
<activity
android:name=".Activity.HomeActivity"
android:label="#string/title_activity_home"
android:theme="#style/AppTheme" />
<meta-data
android:name="com.google.android.gms.vision.DEPENDENCIES"
android:value="barcode" />
<activity android:name=".Activity.QRActivity" />
<activity
android:name=".Activity.BluetoothActivity"
android:label="#string/title_activity_bluetooth"
android:theme="#style/AppTheme"></activity>
</application>
</manifest>

getApplication() inside an activity returns an object of type Application. In your case you are trying to cast this object into TSLBluetoothDeviceApplication which, as defined by you, is an Activity type class.
As I see, you are trying to call getCommander() which is defined already in your TSL activity class. I assume you want getCommander() method from another class.. Make sure which one is.
public AsciiCommander getCommander(){
return ((TSLBluetoothDeviceApplication) getApplication()).getCommander();
}
This method is already inside TSLBluetoothDeviceApplication class.. I don't know what are you trying to achieve by trying to call same method which is already in your current class.
EDIT:
After the edited post, we noticed that the class was properly implemented, just forgot to add
android:name="com.path.to.ApplicationClass" into the Manifestfile under <application/> tag.
I will let the above answer also, because it may help others
Happy coding <3

It's clear that your application class is not used. You need to add it to your xml Application tag like this:
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:roundIcon="#mipmap/ic_launcher_round"
android:supportsRtl="true"
android:name="com.siscaproject.sisca.Utilities. TSLBluetoothDeviceApplication"
android:theme="#style/AppTheme"
tools:replace="android:icon">
and the only change is adding android:name="com.siscaproject.sisca.Utilities. TSLBluetoothDeviceApplication" to the Application tag as your customized class.

avoid of send null from destroyed activity to restarted service

I want to programing app for data track in background , so I use service .
I want to write a program that monitors all data sent and received by the device, and when the total volume of received or received messages reaches a specified value, the Internet device is turned off.
So I used the following code to monitor the data:
 
mStartRX = TrafficStats.getTotalRxBytes ();
mStartTX = TrafficStats.getTotalTxBytes ();
And I used the services to work on the background in the background.
To specify the download or upload limit from the user with edittext, I requested this limit in mainactivity and send this value to the service.
The problem is when: When I destroy the program, I will restart the service and get the NULL value and the program crashes.
My application code:
Main Activity :
package ir.alexandre9009.service;
import android.app.AlertDialog;
import android.content.Context;
import android.net.TrafficStats;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.os.Handler;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class MainActivity extends Activity {
public static Handler mHandler = new Handler();
public static long UPP;
public static long DLL;
Button startService,stopService;
public Context context=this;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (FirstService.mStartRX == TrafficStats.UNSUPPORTED || FirstService.mStartTX == TrafficStats.UNSUPPORTED) {
AlertDialog.Builder alert = new AlertDialog.Builder(this);
alert.setTitle("Uh Oh!");
alert.setMessage("Your device does not support traffic stat monitoring.");
alert.show();
} else {
mHandler.postDelayed(mRunnable, 1000);
}
startService=(Button)findViewById(R.id.startService);
stopService=(Button)findViewById(R.id.stopService);
startService.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
EditText UP = (EditText) findViewById(R.id.UP);
String UPPP = UP.getText().toString();
UPP=Long.parseLong(UPPP);
EditText DL = (EditText) findViewById(R.id.DL);
String DLLL = DL.getText().toString();
DLL=Long.parseLong(DLLL);
Intent intent = new Intent(getApplicationContext(), FirstService.class);
String myString = DLLL;
intent.putExtra("StringName", myString);
startService(intent);
}
});
stopService.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
stopService(new Intent(getBaseContext(),FirstService.class));
}
});
}
public final Runnable mRunnable = new Runnable() {
public void run() {
TextView RX = (TextView)findViewById(R.id.RX);
TextView TX = (TextView)findViewById(R.id.TX);
RX.setText(Long.toString(FirstService.rxBytes));
TX.setText(Long.toString(FirstService.txBytes));
mHandler.postDelayed(mRunnable, 1000);
}
};
}
Service :
package ir.alexandre9009.service;
import android.app.AlertDialog;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.net.TrafficStats;
import android.net.wifi.WifiManager;
import android.os.Handler;
import android.os.IBinder;
import android.widget.TextView;
import android.widget.Toast;
public class FirstService extends Service{
public static long mStartRX ;
public static long mStartTX ;
public static long rxBytes ;
public static long txBytes ;
public long dl=MainActivity.DLL;
Context context=this;
private final Runnable mRunnable = new Runnable() {
public void run() {
rxBytes = (TrafficStats.getTotalRxBytes()- mStartRX)/1048576;
txBytes = (TrafficStats.getTotalTxBytes()- mStartTX)/1048576;
if (rxBytes==2) {
stopService(new Intent(getBaseContext(),FirstService.class));
Intent i = new Intent(context,MainActivity.class);
context.startActivity(i);
// WifiManager wifiManager = (WifiManager)getApplicationContext().getSystemService(Context.WIFI_SERVICE);
// wifiManager.setWifiEnabled(false);
//معرفی توست برای نمایش یک پیام کوتاه به کاربر در هنگام خاموش کردن وای فای
Toast.makeText(FirstService.this, "هشدار", Toast.LENGTH_LONG).show();
}
mHandler.postDelayed(mRunnable, 1000);
}
};
private Handler mHandler = new Handler();
#Override
public IBinder onBind(Intent arg0) {
return null;
}
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
Toast.makeText(this,"staart",Toast.LENGTH_LONG).show();
mStartTX=0;
mStartRX=0;
mStartRX = TrafficStats.getTotalRxBytes();
mStartTX = TrafficStats.getTotalTxBytes();
mHandler.postDelayed(mRunnable, 1000);
return Service.START_STICKY;
}
#Override
public void onDestroy() {
TrafficStats.clearThreadStatsTag();
Toast.makeText(this,"FirstService Stoped",Toast.LENGTH_LONG).show();
mStartTX=0;
mStartRX=0;
super.onDestroy();
}
}
AndroidManifest :
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="ir.alexandre9009.service">
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE"/>
<uses-permission android:name="android.permission.UPDATE_DEVICE_STATS" />
<uses-permission android:name="android.permission.WAKE_LOCK" />
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:roundIcon="#mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<service android:name=".FirstService"
>
</service>
</application>
</manifest>
please help me ...

The problem is with this line
public long dl=MainActivity.DLL;
You're referring to a variable in the Activity, surly when the Activity is destroyed, this variable is no longer in scope, thus you get Null Exception.
You must get this value using the intent.
The other problem is that you can't prevent any service from being killed by the system except foreground services which need to show a notification to the user. But this is not suitable for your situation.
Therefore, the best approach for you is to check whether intent is null or not. If it is not null, you get the value and save it into Preferences or Database or somewhere, if it is null, you retrieve the value from where you stored it before.

Android Studio app crashes

I have a problem with my application I am making on Android Studio. I don't know why, but after the splash screen, the application crashes. I want the activity "Accueil" to open after the splash screen. It worked fine last week and now it doesn't anymore. I didn't touch anything. I show you the manifest, and the .java files.
Splashscreen.java:
import android.app.Activity;
import android.content.Intent;
import android.graphics.PixelFormat;
import android.os.Bundle;
import android.view.Window;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.ImageView;
import android.widget.LinearLayout;
public class Splashscreen extends Activity {
public void onAttachedToWindow() {
super.onAttachedToWindow();
Window window = getWindow();
window.setFormat(PixelFormat.RGBA_8888);
}
Thread splashTread;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_splashscreen);
StartAnimations();
Thread loading = new Thread() {
public void run() {
try {
sleep(5000);
Intent main = new Intent(Splashscreen.this,Menu.class);
startActivity(main);
finish();
} catch (Exception e) {
e.printStackTrace();
} finally {
finish();
}
}
};
loading.start();
}
private void StartAnimations() {
Animation anim = AnimationUtils.loadAnimation(this, R.anim.alpha);
anim.reset();
LinearLayout l = (LinearLayout) findViewById(R.id.lin_lay);
l.clearAnimation();
l.startAnimation(anim);
anim = AnimationUtils.loadAnimation(this, R.anim.rotate);
anim.reset();
ImageView iv = (ImageView) findViewById(R.id.splash);
iv.clearAnimation();
iv.startAnimation(anim);
splashTread = new Thread() {
#Override
public void run() {
try {
int waited = 0;
while (waited < 3500) {
sleep(100);
waited += 100;
}
Intent intent = new Intent(Splashscreen.this,Menu.class);
startActivity(intent);
finish();
} catch (InterruptedException e) {
}
}
};
}
}
Android Manifest:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.thibaudmangeot.erdfapplicationsecurite">
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme">
<activity android:name=".Splashscreen"
android:label="#string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.LAUNCHER"/>
</intent-filter>
</activity>
<activity android:name=".Accueil"
android:label="#string/title_activity_accueil"/>
</application>
</manifest>
Accueil.java:
package com.example.thibaudmangeot.erdfapplicationsecurite;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.widget.Button;
import android.view.View;
public class Accueil extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_accueil);
Button buttonfis = (Button) findViewById(R.id.buttonfis);
buttonfis.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
goTosignin();
}
});
}
private void goTosignin() {
Intent intent = new Intent(this, Menu.class);
startActivity(intent);
}
}

Do this
Intent main = new Intent(Splashscreen.this, Accueil.class);
startActivity(main);
finish();
Instead of
Intent main = new Intent(Splashscreen.this, Menu.class);
startActivity(main);
finish();
You have not even mentioned Menu activity in your manifest.

This is your error:
Intent main = new Intent(Splashscreen.this,Menu.class);
it should be:
Intent main = new Intent(Splashscreen.this, Accueil.class);

I think your application is crashing maybe because of two reasons
There is no Activity named "Menu"
Menu Activity is not mentioned in manifest file
If you want to open "Accueil" activity then write your intent in following fashion.
Intent openAccueil = new Intent(Splashscreen.this,Menu.class);
startActivity(openAccueil);