java使用alarm manager在特定时间发送通知

Question

我试图通过使用报警管理器和待定意图在特定时间发送通知，但什么也没有显示！ 请帮忙

这是密码

主要活动类

public class MainActivity extends Activity {

DatePicker dp;
TimePicker tp;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    dp=findViewById(R.id.datePicker1);
    tp=findViewById(R.id.datePicker);
}

 public void go(View b){

    Calendar now = Calendar.getInstance();
    Log.d("hello","date now "+now.getTimeInMillis()+"");
    Calendar startTIme= Calendar.getInstance();
    startTIme.set(dp.getYear(),dp.getMonth(),dp.getDayOfMonth(),tp.getCurrentHour(),tp.getCurrentMinute(),0);
    Log.d("hello","date chosen "+startTIme.getTimeInMillis()+"");
    int k= (int) (startTIme.getTimeInMillis()-now.getTimeInMillis());
    Log.d("hello",k+"");
    scheduleNotification(getNotification("5 second delay"),k);
 }

  private void scheduleNotification(Notification notification, int delay) {

    Intent notificationIntent = new Intent(this, MyReceiver.class);
    notificationIntent.putExtra(MyReceiver.NOTIFICATION_ID, 1);
    notificationIntent.putExtra(MyReceiver.NOTIFICATION, notification);
    PendingIntent pendingIntent = PendingIntent.getBroadcast(this, 0, notificationIntent, PendingIntent.FLAG_UPDATE_CURRENT);
    long futureInMillis = SystemClock.elapsedRealtime() + delay;
    AlarmManager alarmManager = (AlarmManager)getSystemService(Context.ALARM_SERVICE);
    alarmManager.set(AlarmManager.ELAPSED_REALTIME_WAKEUP, futureInMillis, pendingIntent);
}

private Notification getNotification(String content) {
    Notification.Builder builder = new Notification.Builder(this);
    builder.setContentTitle("Scheduled Notification");
    builder.setContentText(content);
    builder.setSmallIcon(R.drawable.ic_launcher_background);
    return builder.build();
}
}

广播接收机类

public class MyReceiver extends BroadcastReceiver {
public MyReceiver() {
}

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);
    int id = intent.getIntExtra(NOTIFICATION_ID, 0);
    notificationManager.notify(id, notification);

}
} 

我在清单文件中添加了接收者，但没有显示通知