stopping Timer after certain number of actions

[John Greenauer]

Hi,

This is my first post here, so please bear with me.

I want to make my simple program print "Action" 5 times and then stop. The code below will print "Action" once per second forever. If I un-comment the timer.cancel(); it stops before it even prints once. I've tried putting the timer inside a for loop and inside a while loop, but can't make them work.

What am I missing?

Thanks in advance.

- Johnny

import java.util.Timer;
import java.util.TimerTask;

public class Race
{
	public static void main( String[] args )
	{

	int delay = 1000; // delay for 1 sec. 
	int period = 1000; // repeat every sec. 
	Timer timer = new Timer(); 
	int counter = 0;

	
	timer.scheduleAtFixedRate(new TimerTask() 
		{
		public void run() {System.out.println( "Action" ); 
		} 
		}, delay, period); 

	//timer.cancel();
	
	}
}

[Christophe Verré]

Hi, welcome to the ranch
I enclosed your source in [code] tags. Please UseCodeTags the next time you post some code.

About your problem, why don't you put the counter variable inside the anonymous TimerTask, increment it and cancel when it reaches five ?

[John Greenauer]

Thanks for your reply

I'm not having much success with that. The code below causes "Action to be print 5 times immediately, every second (after the 1 second delay). I believe that the 1 second delay in the timer method does not prevent the computer from running through the for loop quickly. So, 5 timers are created in less than a second and they all activate after the one second delay. Also, if the timer.cancel(); is un-commented, the program prints nothing because it ends before the one second delay has run it's course. I've tried a slightly different version of this with the timer.cancel(); placed within an if( count == 4) loop. It also prints nothing.

Perhaps the timer method will not work the way I want it to. Maybe, I need a different method. Any thoughts?

import java.util.Timer;
import java.util.TimerTask;

public class Race
{
	public static void main( String[] args )
	{

	int delay = 1000; // delay for 1 sec. 
	int period = 1000; // repeat every sec. 
	Timer timer = new Timer(); 

	// This causes Action to by printed 5 times every second

		timer.scheduleAtFixedRate(new TimerTask() 
		{
				public void run() 
				{
					for(int count = 0; count < 5; count ++ )
					{
						System.out.println( "Action" ); 
					}
				} 
		}, delay, period); 
		//timer.cancel();

	}
	
}

[Christophe Verré]

I'm not talking about looping 5 times in the TimerTask. The Timer will call the task, that's its job, not yours. What I'm talking about is to put the "int counter" inside the TimerTask, to increment it when the task is called (i.e in the run() method), and to cancel the timer when the counter reaches 5.

[John Greenauer]

O.K. I finally got it. That definitely took longer than it should have.

I was getting an error message with timer.cancel(); , but System.exit(0); worked straight off. I've put the final product below for any rookies (like me) that might look for it.

Thanks for the help.

import java.util.Timer;
import java.util.TimerTask;

public class Race
{
	public static void main( String[] args )
	{

	int delay = 1000; // delay for 1 sec. 
	int period = 1000; // repeat every sec. 
	Timer timer = new Timer(); 

		timer.scheduleAtFixedRate(new TimerTask() 
		{
			int count = 0;

			public void run() 
			{
				System.out.println( "Action" ); 
				count ++;		
						
				if(count == 5) 
					System.exit(0);
			} 
				
		}, delay, period); 
		
	}
	
}

[Christophe Verré]

I was getting an error message with timer.cancel(); , but System.exit(0); worked straight off.

Dooh this.cancel() would do the trick.

[John Greenauer]

Ahh. Yes, that does work. I haven't gotten to "this" in my book yet. I see that it stops printing "Action" without stopping the program. I can see how that's probably a better option in most cases. Thanks a lot.