Perform a task on a specific date and time

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I’m trying to develop a small system that sends a e-mail every Tuesday at 08:00 in the morning.

But I’m a little confused, I can already send the email and check if it’s Tuesday, but I don’t know if it’s correct.

The system keeps running, however as I am still not checking if it is 08:00 in the morning it should not send several emails non-stop, since the only condition for sending emails is to be Tuesday?

Here is the code:

public void gerarAviso() {
    Timer timer = null;
    if (timer == null) {
        timer = new Timer();
        Calendar data = Calendar.getInstance();
        TimerTask tarefa = new TimerTask() {
            @Override
            public void run() {
                System.err.println("DATA: " + data);
                if (data.get(Calendar.DAY_OF_WEEK) == Calendar.TUESDAY){
                    System.out.println("É terça feira");
                    EnviaEmail e = new EnviaEmail();
                    e.enviaEmail("[email protected]");
                }else {
                        System.out.println("Não é terça feira!");
                }    
            }
        };
        timer.schedule(tarefa, data.getTime());
    }
}
java thread date calendar task

  • Send multiple emails? This code block is being called inside some loop like for or while?

  • Send only one. I just want to send it every Tuesday at 8:00 am, IE, the system will run non-stop

  • I’m referring to your question ele não deveria enviar vários emails sem parar, já que a única condição para envio de emails é ser Terça?... Surely he shouldn’t send several e-mails, the code block will only be executed once. (Unless it is being called inside a repeat loop)

  • Aa yes, that would be by condition, it should send only one but it continues to be executed in Task.

  • But is something going wrong with this code? What is the problem you need to solve?

  • The problem is that I do not know if it is correct, he makes the first check and checks if it is Tuesday but I do not know a way to test to see if it continues running. The only way I could see would be to let it run until tomorrow

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1 answer

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The method Schedule(Timertask task, Date time) only performs the task once. I will recommend you to use the method: scheduleAtFixedRate(Timertask task, Date firsttime, long period) for the method to be repeated day by day. Remembering that the period is measured in milliseconds.

It can also be done a loop manually that waits a day to check the day of the week and send the email.

Source: http://docs.oracle.com/javase/7/docs/api/java/util/Timer.html

  • Thank you @Shura16. I do a check every 1 hour to see if the day is Tuesday and if it’s 8:00. This way the system is always running and checking.

  • It can also be, would be careful to check only the hour and not the minutes and seconds. If for any reason there is a delay in the system and pass these seconds or minutes the task will not be executed.

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