Question

I want to perform a task using Java at specific, given hour. My code works, but it doesn’t look good. I’m comparing two strings. I tried to compare dates using getTimeInMills() but numbers aren’t the same.

Here’s my code:

import java.util.Calendar;

class Voter {
Calendar current,deadline;
boolean keepGoing = true;

public static void main(String[] args) {
    Voter strzal = new Voter();
    strzal.shoot();
}

public void shoot() {
    deadline = Calendar.getInstance();
    deadline.set(2011,6,21,11,20,00);

    while (keepGoing) {
        // wait 1 second
        try {
            Thread.sleep(1000);
            System.out.print(".");
        } catch (InterruptedException ex) { ex.printStackTrace(); }

        current = Calendar.getInstance();

        if (deadline.getTime().toString().equals(current.getTime().toString())) {
            System.out.println("Got it!");
            keepGoing = false;
        } // end of if
    } // end of while
} // end of shoot() method

}

I’m running in the loop, waiting for the current time to be equal to deadline (in an example I set it to 21st July 2011 11:10 AM).

How can I improve my code? I’d like to use for example compareTo() or getTimeInMills() method from Calendar class, but I can’t set deadline properly.

Thanks in advance.

Answer 1

Using a ScheduledExecutorService is a better suggestion, however for your knowledge

Calendar deadline = Calendar.getInstance();
deadline.set(2011,6,21,11,20,00);
long endTime = deadline.getTime().getTime();

// later
long current = System.currentTimeMillis();
if (current >= endTime) {
    System.out.println("Got it!");
    break;
}