Notification at a certain time with no need to open the program

Question

package com.example.dell.notification;
import android.annotation.TargetApi;
import android.media.RingtoneManager;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.text.format.Time;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.app.Activity;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.widget.Button;
import android.widget.Toast;


import java.text.SimpleDateFormat;
import java.util.Date;


public class MainActivity extends ActionBarActivity {  

@Override
protected void onCreate(Bundle savedInstanceState)  {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
   String currentDateandTime = sdf.format(new Date());

if(currentDateandTime=="2015-05-15"){

}
            showNotification();


}


@TargetApi(Build.VERSION_CODES.JELLY_BEAN)
public void showNotification(){

    // define sound URI, the sound to be played when there's a notification
    Uri soundUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);

    // intent triggered, you can add other intent for other actions
    Intent intent = new Intent(MainActivity.this, NotificationReceiver.class);
    PendingIntent pIntent = PendingIntent.getActivity(MainActivity.this, 0, intent, 0);

    // this is it, we'll build the notification!
    // in the addAction method, if you don't want any icon, just set the first param to 0
    Notification mNotification = new Notification.Builder(this)

            .setContentTitle("Vigilia dos Obreiros")
            .setContentText("Hoje, as 22 horas")
            .setSmallIcon(R.drawable.ic_launcher)
            .setContentIntent(pIntent)
            .setSound(soundUri)

            .addAction(R.drawable.abc_ic_ab_back_mtrl_am_alpha, "View", pIntent)
            .addAction(0, "Remind", pIntent)

            .build();

    NotificationManager notificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);

    // If you want to hide the notification after it was selected, do the code below
    // myNotification.flags |= Notification.FLAG_AUTO_CANCEL;

    notificationManager.notify(0, mNotification);
}

public void cancelNotification(int notificationId){

    if (Context.NOTIFICATION_SERVICE!=null) {
        String ns = Context.NOTIFICATION_SERVICE;
        NotificationManager nMgr = (NotificationManager) getApplicationContext().getSystemService(ns);
        nMgr.cancel(notificationId);
    }
}
}

Answer 1

Define a Alarmmanager to call a Broadcastreceiver which will launch the notification:

//Definir a data
Calendar calendar = Calendar.getInstance();
calendar.set(Calendar.YEAR, 2015);
calendar.set(Calendar.MONTH, 5);
calendar.set(Calendar.DAY, 15);
//calendar.set(Calendar.HOUR_OF_DAY,10) //Se quiser indicar a hora
//calendar.set(Calendar.MINUTE,25)//Se quiser indicar os minutos
Intent intent = new Intent(MainActivity.this, LancaNotificacoaReceiver.class);
PendingIntent pIntent = PendingIntent.getBroadcast(MainActivity.this,0, intent,0);

AlarmManager alarmManager = (AlarmManager)context.getSystemService(Context.ALARM_SERVICE);

//Definir o alarme para acontecer no dia determinado
alarmManager.set(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), pIntent);  

Define the Broadcastreceiver LancaNotificacoaReceiver and in the method onReceive create the notification:

public class LancaNotificacoaReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {

        //      código da notificação
    }

}  

Don’t forget to register Broadcastreceiver on Androidmanifest.xml

<receiver android:name="a_sua_package.LancaNotificacoaReceiver"/>