alarm is not triggered at particular time

Question

Update

The alarm service is not getting on at selected date and time.

add_task_frag (fragment that triggers alarm) :

Intent intent = new Intent(getActivity(), AlarmReceiver.class);
PendingIntent pendingIntent = PendingIntent.getService(getActivity(), 0, intent, 0);
AlarmManager am = (AlarmManager)getActivity().getSystemService(Context.ALARM_SERVICE);
am.set(AlarmManager.RTC_WAKEUP, 5000, pendingIntent);

The alarm should go on after 5 seconds but it doesn't happen. if I put this code (for pending intent)

PendingIntent pendingIntent = PendingIntent.getActivity(getActivity(), 0, intent, 0);

then alarm goes on immediately after button click instead of after 5 seconds.

Below is alarm receiver class :

super.onCreate(savedInstanceState);
    PowerManager powerManager = (PowerManager)getSystemService(Context.POWER_SERVICE);
    wakeLock = powerManager.newWakeLock(PowerManager.FULL_WAKE_LOCK, "My Wake Lock");
    wakeLock.acquire();
    this.requestWindowFeature(Window.FEATURE_NO_TITLE);
    this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN | WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED | WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON,
            WindowManager.LayoutParams.FLAG_FULLSCREEN | WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED | WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON);
    setContentView(R.layout.alarm);

    Button stopalarm = (Button)findViewById(R.id.stop);
    stopalarm.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            mediaPlayer.stop();
            finish();
        }
    });
    playSound (this, getAlarmUri());
}
private void playSound (Context context, Uri alert){
    mediaPlayer = new MediaPlayer();
    try{
        mediaPlayer.setDataSource(context, alert);
        final AudioManager audioManager = (AudioManager)context.getSystemService(AUDIO_SERVICE);
        if (audioManager.getStreamVolume(AudioManager.STREAM_ALARM) != 0){
            mediaPlayer.setAudioStreamType(AudioManager.STREAM_ALARM);
            mediaPlayer.prepare();
            mediaPlayer.start();
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}
private Uri getAlarmUri(){
    Uri alert = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_ALARM);
    if (alert == null){
        alert = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
        if (alert == null){
            RingtoneManager.getDefaultUri(RingtoneManager.TYPE_RINGTONE);
        }
    }
    return alert;
}

@Override
protected void onStop() {
    super.onStop();
    wakeLock.release();
}

Answer 1

triggerAtMillis argument of set method is the time when alarm should be triggered. If it is less, than current time, then alarm will be triggered immediately. Thus you made a mistake, it should be System.currentTimeMillis() + 5000 instead of just 5000.