How to set an Android notification to a specific date in the future

activity_main.xml

<? xml version = "1.0" encoding = "utf-8" ?>
<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 :padding = "16dp"
   tools :context = ".MainActivity" >
   <TextView
      android :id = "@+id/tvDate"
      android :layout_width = "match_parent"
      android :layout_height = "wrap_content"
      android :hint = "Select Date"
      android :onClick = "setDate"
      android :padding = "16dp" />
</RelativeLayout>

AndroidManifest.xml

<? xml version = "1.0" encoding = "utf-8" ?>
<manifest xmlns: android = "http://schemas.android.com/apk/res/android"
   package = "app.tutorialspoint.com.notifyme" >
   <uses-permission android :name = "android.permission.VIBRATE" />
   <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>
      <receiver android :name= ".MyNotificationPublisher" />
   </application>
</manifest>

MainActivity.java

package app.tutorialspoint.com.notifyme ;
import android.app.AlarmManager ;
import android.app.DatePickerDialog ;
import android.app.Notification ;
import android.app.PendingIntent ;
import android.content.Context ;
import android.content.Intent ;
import android.os.Bundle ;
import android.support.v4.app.NotificationCompat ;
import android.support.v7.app.AppCompatActivity ;
import android.view.View ;
import android.widget.Button ;
import android.widget.DatePicker ;
import java.text.SimpleDateFormat ;
import java.util.Calendar ;
import java.util.Date ;
import java.util.Locale ;
public class MainActivity extends AppCompatActivity {
   public static final String NOTIFICATION_CHANNEL_ID = "10001" ;
   private final static String default_notification_channel_id = "default" ;
   Button btnDate ;
   final Calendar myCalendar = Calendar. getInstance () ;
   @Override
   protected void onCreate (Bundle savedInstanceState) {
      super .onCreate(savedInstanceState) ;
      setContentView(R.layout. activity_main ) ;
      btnDate = findViewById(R.id. btnDate ) ;
   }
   private void scheduleNotification (Notification notification , long delay) {
      Intent notificationIntent = new Intent( this, MyNotificationPublisher. class ) ;
      notificationIntent.putExtra(MyNotificationPublisher. NOTIFICATION_ID , 1 ) ;
      notificationIntent.putExtra(MyNotificationPublisher. NOTIFICATION , notification) ;
      PendingIntent pendingIntent = PendingIntent. getBroadcast ( this, 0 , notificationIntent , PendingIntent. FLAG_UPDATE_CURRENT ) ;
      AlarmManager alarmManager = (AlarmManager) getSystemService(Context. ALARM_SERVICE ) ;
      assert alarmManager != null;
      alarmManager.set(AlarmManager. ELAPSED_REALTIME_WAKEUP , delay , pendingIntent) ;
   }
   private Notification getNotification (String content) {
      NotificationCompat.Builder builder = new NotificationCompat.Builder( this, default_notification_channel_id ) ;
      builder.setContentTitle( "Scheduled Notification" ) ;
      builder.setContentText(content) ;
      builder.setSmallIcon(R.drawable. ic_launcher_foreground ) ;
      builder.setAutoCancel( true ) ;
      builder.setChannelId( NOTIFICATION_CHANNEL_ID ) ;
      return builder.build() ;
   }
   DatePickerDialog.OnDateSetListener date = new DatePickerDialog.OnDateSetListener() {
      @Override
      public void onDateSet (DatePicker view , int year , int monthOfYear , int dayOfMonth) {
         myCalendar .set(Calendar. YEAR , year) ;
         myCalendar .set(Calendar. MONTH , monthOfYear) ;
         myCalendar .set(Calendar. DAY_OF_MONTH , dayOfMonth) ;
         updateLabel() ;
      }
   } ;
   public void setDate (View view) {
      new DatePickerDialog(
         MainActivity. this, date ,
         myCalendar .get(Calendar. YEAR ) ,
         myCalendar .get(Calendar. MONTH ) ,
         myCalendar .get(Calendar. DAY_OF_MONTH )
      ).show() ;
   }
   private void updateLabel () {
      String myFormat = "dd/MM/yy" ; //In which you need put here
      SimpleDateFormat sdf = new SimpleDateFormat(myFormat , Locale. getDefault ()) ;
      Date date = myCalendar .getTime() ;
      btnDate .setText(sdf.format(date)) ;
      scheduleNotification(getNotification( btnDate .getText().toString()) , date.getTime()) ;
   }
}

MyNotificationPublisher.java

package app.tutorialspoint.com.notifyme ;
import android.app.Notification ;
import android.app.NotificationChannel ;
import android.app.NotificationManager ;
import android.content.BroadcastReceiver ;
import android.content.Context ;
import android.content.Intent ;
import static app.tutorialspoint.com.notifyme.MainActivity. NOTIFICATION_CHANNEL_ID ;
public class MyNotificationPublisher extends BroadcastReceiver {
   public static String NOTIFICATION_ID = "notification-id" ;
   public static String NOTIFICATION = "notification" ;
   public void onReceive (Context context , Intent intent) {
      NotificationManager notificationManager = (NotificationManager) context.getSystemService(Context. NOTIFICATION_SERVICE ) ;
      Notification notification = intent.getParcelableExtra( NOTIFICATION ) ;
      if (android.os.Build.VERSION. SDK_INT >= android.os.Build.VERSION_CODES. O ) {
         int importance = NotificationManager. IMPORTANCE_HIGH ;
         NotificationChannel notificationChannel = new NotificationChannel( NOTIFICATION_CHANNEL_ID , "NOTIFICATION_CHANNEL_NAME" , importance) ;
         assert notificationManager != null;
         notificationManager.createNotificationChannel(notificationChannel) ;
      }
      int id = intent.getIntExtra( NOTIFICATION_ID , 0 ) ;
      assert notificationManager != null;
      notificationManager.notify(id , notification) ;
   }
}