Develop Reference

Getting NULL in context while auto restart with BROADCAST RECEIVER in Android app

I am developing android application which need auto restart when restart device for that I am using broadcast receiver with action BOOT_COMPLETED.
Broadcast receiver is receiving message when I am restarting device but in restart method I want to start main activity for that I used Intent but in onReceive method of receiver I am getting null context so I am unable to restart main Activity.
Below is code for that.
MainActivity.java
private Object activity;
private TextView tvImeiNum;
private BroadcastReceiver rebootreceiver;
private IntentFilter filter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tvImeiNum = (TextView)findViewById(R.id.tv_imeinum);
filter = new IntentFilter();
filter.addAction(Intent.ACTION_BOOT_COMPLETED);
filter.addAction(Intent.ACTION_REBOOT);
rebootreceiver = new BootUpReceiver(MainActivity.this);
LocalBroadcastManager.getInstance(this).registerReceiver(rebootreceiver,
filter);//registering receiver
generateUniqueCode();
}
BootupReceiver.java
public class BootUpReceiver extends BroadcastReceiver {
MainActivity ma;
public BootUpReceiver(MainActivity maContext){
ma=maContext;
}
public BootUpReceiver(){
}
#RequiresApi(api = Build.VERSION_CODES.M)
#Override
public void onReceive(Context context, Intent intent) {
if (intent.getAction().equals("android.intent.action.BOOT_COMPLETED")) {
Log.d("TAG REBOOT", "onReceive: " + intent);
Log.d("Reboot complete", "connection");
GlobalTool.restartApplication(context);
}
}
}
GlobalTool.java
public class GlobalTool {
#RequiresApi(api = Build.VERSION_CODES.M)
public static void restartApplication(Context context) {
Log.d("IN App restart:", "");
Log.d("TAG", "restartApplication: ");
if(context != null)
{
Log.d("TAG NULL", "restartApplication: ");
Intent mainIntent = new Intent(context, MainActivity.class);
AlarmManager alarmMgr = (AlarmManager)
context.getSystemService(ALARM_SERVICE);
TaskStackBuilder stackBuilder = TaskStackBuilder.create(context);
stackBuilder.addNextIntent(mainIntent);
PendingIntent pendingIntent = stackBuilder.getPendingIntent(0,
PendingIntent.FLAG_UPDATE_CURRENT);
long alarmTime = System.currentTimeMillis() + (1 * 1000);
alarmMgr.setExact(AlarmManager.RTC_WAKEUP, alarmTime, pendingIntent);
Log.d("TAG", "restartApplication: 111");
Log.d("TAG", "restartApplication: 111");
}
else {
Intent mainIntent = new Intent(context, MainActivity.class);
AlarmManager alarmMgr = (AlarmManager)
context.getSystemService(ALARM_SERVICE);
TaskStackBuilder stackBuilder = TaskStackBuilder.create(context);
stackBuilder.addNextIntent(mainIntent);
PendingIntent pendingIntent = stackBuilder.getPendingIntent(0,
PendingIntent.FLAG_UPDATE_CURRENT);
long alarmTime = System.currentTimeMillis() + (1 * 1000);
alarmMgr.setExact(AlarmManager.RTC_WAKEUP, alarmTime, pendingIntent);
Log.d("TAG", "restartApplication: 111");
Log.d("TAG", "restartApplication: 111");
}
}
}
AndroidManifest.xml
<?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.example.kioskappdemo">
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission
android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
<application
android:name="KioskApplication"
android:allowBackup="true"
android:dataExtractionRules="#xml/data_extraction_rules"
android:fullBackupContent="#xml/backup_rules"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:roundIcon="#mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="#style/Theme.KioskAppDemo"
tools:targetApi="31"
tools:ignore="Instantiatable">
<service
android:name=".RebootService"
android:enabled="true"
android:exported="true"></service>
<activity
android:name=".MainActivity"
android:exported="true"
android:screenOrientation="landscape"
android:theme="#style/Theme.AppCompat.NoActionBar">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category
android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<receiver
android:name=".Activity.BootUpReceiver"
android:enabled="true"
android:exported="true">
<intent-filter >
<action
android:name="android.intent.action.BOOT_COMPLETED" />
<action android:name="android.intent.action.REBOOT" />
<action
android:name="android.intent.action.QUICKBOOT_POWERON" />
<action android:name="com.reboot.test" />
<action
android:name="android.intent.action.TIMEZONE_CHANGED" />
<action
android:name="android.intent.action.DATE_CHANGED" />
</intent-filter>
</receiver>
</application>
</manifest>

Some you code improvements:
Don't put context to Brodcast Receiver constructor. Use the Context from onReceive method
public class BootUpReceiver extends BroadcastReceiver {
public BootUpReceiver(){
//TODO log
}
...
You should not use LocalBroadcastManager::registerReceiver call. If Broadcast receiver is added to AndroidManifest then it will be started by the system.
<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
<receiver
android:name=".activity.BootUpReceiver"
android:enabled="true"
android:exported="true"
android:permission="android.permission.RECEIVE_BOOT_COMPLETED">
<intent-filter >
<action android:name="android.intent.action.BOOT_COMPLETED" />
</intent-filter>
</receiver>
Don't use CamelCase for package names (use .activity.BootUpReceiver insetad .Activity.BootUpReceiver)

Unable to show notification when app is closed

I am trying to show notification at specific date I am using alarm manager and broadcast receiver to show notifications but the problem is notification works only when app is open and when app is closed notification does not show. Below is my code:
Reminder.java
public class Reminder extends AppCompatActivity {
long reminderDateTimeInMilliseconds = 000;
Button but;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_reminder);
but = findViewById(R.id.but);
but.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
createNotifyChannel();
Intent intent = new Intent(Reminder.this,ReminderBroadcast.class);
PendingIntent pendingIntent = PendingIntent.getBroadcast(Reminder.this,0,intent,0);
AlarmManager alarmManager = (AlarmManager)getSystemService(Context.ALARM_SERVICE);
Calendar calendarToSchedule = Calendar.getInstance();
calendarToSchedule.setTimeInMillis(System.currentTimeMillis());
calendarToSchedule.clear();
//.Set(Year, Month, Day, Hour, Minutes, Seconds);
calendarToSchedule.set(2020, 8, 20, 19, 12, 0);
reminderDateTimeInMilliseconds = calendarToSchedule.getTimeInMillis();
alarmManager.setExact(AlarmManager.RTC_WAKEUP,reminderDateTimeInMilliseconds,pendingIntent);
}
});
}
private void createNotifyChannel(){
if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.O){
CharSequence name = "ReminChannel";
String desc = "This is my channel";
int importance = NotificationManager.IMPORTANCE_DEFAULT;
NotificationChannel channel = new NotificationChannel("mynotif",name,importance);
channel.setDescription(desc);
NotificationManager notificationManager = getSystemService(NotificationManager.class);
notificationManager.createNotificationChannel(channel);
}
}
}
ReminderBroadcast.java
public class ReminderBroadcast extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
NotificationCompat.Builder notif = new NotificationCompat.Builder(context,"mynotif")
.setContentTitle("Appointment reminder")
.setContentText("Hello there")
.setPriority(NotificationCompat.PRIORITY_DEFAULT);
NotificationManagerCompat manager = NotificationManagerCompat.from(context);
manager.notify(200,notif.build());
}
}
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.app.firstapp">
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_BACKGROUND_LOCATION" />
<uses-permission android:name="android.permission.WRITE_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">
<activity android:name=".Reminder">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".ThirdActivity" />
<activity android:name=".SecondActivity" />
<activity android:name=".MainActivity">
</activity>
<receiver android:name=".ReminderBroadcast"/>
</application>
</manifest>
What am I doing wrong?

Alarm Manager Example does not work

I am trying to follow the example given here on running some code in fixed time intervals. I used the code in this example (setting the waiting time to 1 minute instead), compiled it, started in on my phone, stopped the application on the phone, and waited for several minutes.
However, no Toast was shown and neither any log-entry. I also notice that the Service.onStart seems depreciated.
Is something missing in the example? Do I need to register something when the main activity of the app is started? Or call it from somewhere else in my app? Or maybe something is wrong in the manifest?
AndroidManifest.xml:
<?xml version="1.0" encoding="utf-8"?>
<manifest
xmlns:android="http://schemas.android.com/apk/res/android"
package="com.mypackage.test" >
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.WAKE_LOCK" />
<application>
android:allowBackup="true"
android:icon="#mipmap/stoxx"
android:label="#string/app_name"
android:supportsRtl="true"
android:theme="#style/Theme.AppCompat.Light" >
<activity
android:name=".MainActivity"
android:label="#string/app_name"
android:theme="#style/AppTheme.NoActionBar" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".NewEntryActivity"
android:label="#string/menu_add"
android:theme="#style/AppTheme.NoActionBar"
/>
<activity
android:name=".UserSettingActivity"
android:label="#string/menu_add"
android:theme="#style/AppTheme.NoActionBar"
/>
<receiver
android:process=":remote"
android:name=".Alarm">
</receiver>
</application>
</manifest>

You forgot to include service in your Manifest. Here is all this project that works for me, check it.
Here is my manifest:
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.alarmmanager.just_me.alarmmanager">
<uses-permission android:name="android.permission.WAKE_LOCK"/>
<application android:allowBackup="true" android:label="#string/app_name"
android:icon="#mipmap/ic_launcher" android:supportsRtl="true"
android:theme="#style/AppTheme">
<activity android:name=".MainActivity"
android:label="#string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<receiver android:process=":remote" android:name=".Alarm"/>
<service android:name=".MyService"/>
</application>
Here is Alarm:
public class Alarm extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent)
{
PowerManager pm = (PowerManager) context.getSystemService(Context.POWER_SERVICE);
PowerManager.WakeLock wl = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "");
wl.acquire();
// Put here YOUR code.
Toast.makeText(context, "com.alarmmanager.just_me.alarmmanager.Alarm !!!!!!!!!!", Toast.LENGTH_LONG).show(); // For example
wl.release();
}
public void SetAlarm(Context context)
{
AlarmManager am =( AlarmManager)context.getSystemService(Context.ALARM_SERVICE);
Intent i = new Intent(context, Alarm.class);
PendingIntent pi = PendingIntent.getBroadcast(context, 0, i, 0);
am.setRepeating(AlarmManager.RTC_WAKEUP, System.currentTimeMillis(), 1000 * 5, pi); // Millisec * Second
}
public void CancelAlarm(Context context)
{
Intent intent = new Intent(context, Alarm.class);
PendingIntent sender = PendingIntent.getBroadcast(context, 0, intent, 0);
AlarmManager alarmManager = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
alarmManager.cancel(sender);
}}
Here is service:
public class MyService extends Service
{
Alarm alarm = new Alarm();
public void onCreate()
{
super.onCreate();
}
#Override
public int onStartCommand(Intent intent, int flags, int startId)
{
Log.d("!~!", "Service started.");
alarm.SetAlarm(this);
return START_STICKY;
}
#Override
public void onStart(Intent intent, int startId)
{
alarm.SetAlarm(this);
}
#Override
public IBinder onBind(Intent intent)
{
return null;
}
}
And the last one MainActivity:
public class MainActivity extends Activity{
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Intent intent = new Intent(this, MyService.class);
startService(intent);
}
}

Android 4.4.4 Kitkat: Broadcastreceiver not receiving on_boot_completed broadcast

My program is to listen receive_boot_complete broadcast when device completes the boot.
The program is working fine as expected with android 4.0.3, but the same thing is not happening when I am running the code on Android 4.4.4 device.
The broadcastreceiver is not receiving a boot completed broadcast.
Is there anything new for Android 4.4.4? Running it on Moto G.
My code is as below:
AndroidManifest
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.my.app"
android:versionCode="1"
android:installLocation="internalOnly"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="15"
android:targetSdkVersion="19" />
<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_INTERNAL_STORAGE" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="com.android.alarm.permission.SET_ALARM" />
<uses-permission android:name="android.permission.INTERNET" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="#string/app_name"
android:excludeFromRecents="true" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<service
android:name=".MyService"
android:label="#string/ser_name"
android:icon="#drawable/serv_ico"
android:enabled="true" />
<receiver
android:name=".BootReceiver"
android:enabled="true"
android:permission="android.permission.RECEIVE_BOOT_COMPLETED" >
<intent-filter>
<action android:name="android.intent.action.BOOT_COMPLETED" />
<action android:name="android.intent.action.QUICKBOOT_POWERON" />
<action android:name="android.intent.action.ACTION_BOOT_COMPLETED" />
</intent-filter>
</receiver>
<receiver
android:name=".AlarmReceiver"
android:enabled="true" >
</receiver>
</application>
BootReceiver
public class BootReceiver extends BroadcastReceiver{
#Override
public void onReceive(final Context context, Intent intent) {
Timer timer = new Timer();
timer.schedule(new TimerTask() {
#Override
public void run() {
// Start alarm manager on boot
// Start service
}
}, 60000);
}
}
AlarmReceiver
public class AlarmReceiver extends BroadcastReceiver {
#Override
public void onReceive(final Context context, Intent intent) {
// Start service
}
}
MainActivity
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Run service on application start
setContentView(R.layout.activity_main);
// Initialize alarm manager application start
PackageManager p = getPackageManager(); // Remove App icon from launcher
p.setComponentEnabledSetting(getComponentName(), PackageManager.COMPONENT_ENABLED_STATE_DISABLED, PackageManager.DONT_KILL_APP);
}
}
AlarmManager
public class Alarm {
public Alarm schedule(Context context) {
Calendar calendar = Calendar.getInstance();
calendar.set(Calendar.HOUR_OF_DAY, 20);
calendar.set(Calendar.MINUTE, 15);
calendar.set(Calendar.SECOND, 0);
AlarmManager am = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
Intent intent = new Intent(context, AlarmReceiver.class);
PendingIntent pi = PendingIntent.getBroadcast(context, 0, intent, 0);
am.setRepeating(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(),AlarmManager.INTERVAL_DAY, pi);
return null;
}
}

You have to define your receiver with exported = true and enabled = true
<android:name=".BootReceiver"
android:enabled="true"
android:exported="true"
android:permission="android.permission.RECEIVE_BOOT_COMPLETED" />

This might be because of a bug in Android 4.4.4 r1/r2
See
Bug in Android KitKat

Alarm doesn't trigger the AlarmReveicer

I am coding a simple alarm test in android, but as mentionned in the title the AlarmReceiver isn't triggered !
i sought here for the solution but none of them worked since my code seems to be correct ...
here is my code :
public class AlarmActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_alarm);
Button salarm = (Button) findViewById(R.id.salarm);
final AlarmManager alarmManager = (AlarmManager)getSystemService(ALARM_SERVICE);
Intent i = new Intent(AlarmActivity.this,AlarmReceiver.class);
final PendingIntent pi = PendingIntent.getBroadcast(getApplicationContext(), 0, i, 0);
salarm.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
alarmManager.set(AlarmManager.RTC_WAKEUP, SystemClock.elapsedRealtime()+(1000*5), pi);
Toast.makeText(getApplicationContext(), "Alarm set, wait 5 sec", Toast.LENGTH_SHORT).show();
}
});
}
Manifest file :
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.androidtest3"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="18" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.androidtest3.MainActivity"
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="AlarmActivity"/>
<receiver
android:exported = "true"
android:name = "AlarmReceiver">
</receiver> <!-- <receiver android:name="AlarmReceiver"/> aurait fait l'affaire -->
</application>
</manifest>
AlarmReceiver Class :
public class AlarmReceiver extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
Toast.makeText(context, "pending intent received !", Toast.LENGTH_SHORT).show();
}
}
it would help if you could explain the any solution you suggest.
thanx

It's likely not happening because the time value is incorrect. If you are going to use RTC_WAKEUP type alarms, get the time using System.currentTimeMillis() plus your additional time. Right now you're using elapsed time, which is not the same as RTC wall clock time.