notification not showing if needed after some time. but working on the spot only

Question

I have 3 buttons in my app

First button is showing notification on button clicked.

Second button is cancelling the shown notification.

Third button has to show notification after 5 seconds.

First and Second button is working but Third one is not working. it is not showing any error in compilation. Can anybody tell me what is wrong with this piece of code?

public void setAlarm(View view) {
        Long alertTime=new GregorianCalendar().getTimeInMillis()+5000;
        Intent alertIntent=new Intent(this,AlertReceiver.class);
        AlarmManager alarmManager=(AlarmManager)
                getSystemService(Context.ALARM_SERVICE);
        alarmManager.set(AlarmManager.RTC_WAKEUP, alertTime,
                 PendingIntent.getBroadcast(this,1, alertIntent,
                         PendingIntent.FLAG_UPDATE_CURRENT));
    }

Here is My complete Activity Main Class

package com.test.notification2;

import android.app.AlarmManager;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.app.TaskStackBuilder;
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.support.v7.widget.Toolbar;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

import java.util.GregorianCalendar;

public class MainActivity extends AppCompatActivity {

    Button showNotificationBut, stopNotificationBut,alertButton;
    NotificationManager notificationManager;

    boolean isNotificActive=false;

    int notifID=33;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        showNotificationBut=(Button)findViewById(R.id.showNotificationBut);
        stopNotificationBut=(Button)findViewById(R.id.stopNotificationBut);
        alertButton=(Button)findViewById(R.id.alertButton);


    }


    public void showNotification(View view) {
        NotificationCompat.Builder notificBuilder= new
                NotificationCompat.Builder(this)
                .setContentTitle("Message")
                .setContentText("New Message")
                .setTicker("Alert New Message")
                .setSmallIcon(R.drawable.my_image);

        Intent moreInfoIntent=new Intent(this,MoreInfoNotification.class);

        TaskStackBuilder taskStackBuilder=TaskStackBuilder.create(this);
        taskStackBuilder.addParentStack(MoreInfoNotification.class);
        taskStackBuilder.addNextIntent(moreInfoIntent);
        PendingIntent pendingIntent=taskStackBuilder.getPendingIntent(0,
                PendingIntent.FLAG_UPDATE_CURRENT);
        notificBuilder.setContentIntent(pendingIntent);

        notificationManager=(NotificationManager)getSystemService(Context.NOTIFICATION_SERVICE);
        notificationManager.notify(notifID, notificBuilder.build());
        isNotificActive=true;


    }

    public void stopNotification(View view) {
        if(isNotificActive){
            notificationManager.cancel(notifID);
        }
    }

    public void setAlarm(View view) {
        Long alertTime=new GregorianCalendar().getTimeInMillis()+5000;
        String s = String.valueOf(alertTime);
        Toast.makeText(this,s,Toast.LENGTH_SHORT).show();

        Intent alertIntent=new Intent(this,AlertReceiver.class);
        AlarmManager alarmManager=(AlarmManager)
                getSystemService(Context.ALARM_SERVICE);
        alarmManager.set(AlarmManager.RTC_WAKEUP, alertTime,
                 PendingIntent.getBroadcast(this,1, alertIntent,
                         PendingIntent.FLAG_UPDATE_CURRENT));
    }
}

Here is AlertReceiver Class:

package com.test.notification2;

import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.support.v4.app.NotificationCompat;

/**
 * Created by waqas on 13/05/2016.
 */
public class AlertReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
       createNotification(context,"Times up","5 seconds has passed",
               "Alert");
    }
    public void createNotification(Context context,String msg,String msgText, String  msgAlert){
        PendingIntent notificIntent=PendingIntent.getActivity(context, 0,
                new Intent(context,MainActivity.class),0);
        NotificationCompat.Builder mBuilder=new NotificationCompat.Builder(context)
                .setSmallIcon(R.drawable.my_image)
                .setContentTitle(msg)
                .setTicker(msgAlert)
                .setContentText(msgText);
        mBuilder.setContentIntent(notificIntent);
        mBuilder.setDefaults(NotificationCompat.DEFAULT_SOUND);
        mBuilder.setAutoCancel(true);
        NotificationManager mNotificationManager=
                (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
        mNotificationManager.notify(1,mBuilder.build());

    }
}

Answer 1

This code works fine . Have you registered the service in the manifest ??

        <receiver android:name=".AlertReceiver">
    </receiver>