How would I have this method run every couple of seconds in a recursive function. I want the i variable to update by 1 every couple of seconds than print it to the console. In javascript I could use setTimeout is there a method like the javascript setTimeout in Java?
final i = 0;
public void timerActions() {
i = i + 1;
System.out.println(i);
}
try with Timer
Timer timer = new Timer("Display Timer");
TimerTask task = new TimerTask() {
@Override
public void run() {
timerActions();
}
};
// This will invoke the timer every second
timer.scheduleAtFixedRate(task, 1000, 1000);
}
You should use ScheduledExecutorService for that.
Update per Peter Lawrey comment (thanks):
Methods :
public ScheduledFuture<?> scheduleAtFixedRate(Runnable command,
long initialDelay,
long period,
TimeUnit unit);
and
public ScheduledFuture<?> scheduleWithFixedDelay(Runnable command,
long initialDelay,
long delay,
TimeUnit unit);
can be used in order to achieve your desired behavior.
You can put the Thread to sleep after execution if it's just a simple application which just has to "run slower".
For example:
final i = 0;
public void timerActions() {
i++;
System.out.println(i);
Thread.sleep(1000);
}
1000 in the parentheses means 1000ms=1second - the amount of time in which the thread sleeps. This is a simple way to do it, but be aware that in larger multi-threaded applications you have to take into acount thread safety and related problems.
Documentation for Thread.sleep()
public class TimedAction
{
public static void main(String[] args) throws Exception
{
System.out.println("begin");
ScheduledExecutorService executor = Executors.newScheduledThreadPool(1);
Runnable command = new Runnable()
{
private int i = 0;
@Override
public void run()
{
// put your logic HERE
System.out.println(i++);
}
};
// execute command, immediately (0 delay), and every 2 seconds
executor.scheduleAtFixedRate(command, 0, 2, TimeUnit.SECONDS);
System.in.read();
executor.shutdownNow();
executor.awaitTermination(5, TimeUnit.SECONDS);
System.out.println("end");
}
}
This will print "Counting..." on every 2 seconds
import java.util.Timer;
import java.util.TimerTask;
public class MyTimerTask extends TimerTask {
private int counter = 0;
public void run() {
counter++;
if (counter <= 3) {
System.out.println("Counting - counter = " + counter);
} else {
System.out.println("Stopping timer execution");
this.cancel();
}
}
public static void main(String[] args) {
Timer timer = new Timer("TimerThreadName");
MyTimerTask task = new MyTimerTask();
// void java.util.Timer.schedule(TimerTask task, long delay, long period)
timer.schedule(task, 0, 2000);
}
}
Thread.sleep(1000);if this is just for fun.