Is thre a "every" in java?

[ytrewqc]

Is there something like "every" in java?
I mean that for example it should print out a number every second.

[camickr]

Create a Thread. Within the thread you create a loop. Inside the loop you print a number and then invoke Thead.sleep(1000).

[JosAH]

You can even make a class implement the Iterable interface; it has to deliver an Iterator which can do what it wants (e.g. wait/sleep for a second before it returns something in its next() method). Iterables can be use in the enhanced for statement.

kind regards,

Jos

[ytrewqc]

Im new to java and i didnt really get it. Can you give me an example?

[JosAH]

Im new to java and i didnt really get it. Can you give me an example?

Sure, just a sec ...

import java.util.Iterator;

class Every implements Iterable<Long> {

	private long interval;
	
	public Every(long interval) { this.interval= interval; }

	private class SecondsIterator implements Iterator<Long> {
		
		public boolean hasNext() { return true; }
		
		public Long next() {
			
			try {
					Thread.sleep(interval);
			}
			catch (InterruptedException ie) { }
			
			return System.currentTimeMillis();
		}
		
		public void remove() { }
	}
	
	public Iterator<Long> iterator() {
		return new SecondsIterator();
	}
	
}
public class T {

	public static void main(String[] args) {
		for (Long t : new Every(1000))
			System.out.println("tick: "+t);
	}
}

I don't think you understand it immediately but there's nothing wrong with reading the API documentation ;-)

kind regards,

Jos

[ytrewqc]

Thanks! It really helped

Sure, just a sec ...

import java.util.Iterator;

class Every implements Iterable<Long> {

	private long interval;
	
	public Every(long interval) { this.interval= interval; }

	private class SecondsIterator implements Iterator<Long> {
		
		public boolean hasNext() { return true; }
		
		public Long next() {
			
			try {
					Thread.sleep(interval);
			}
			catch (InterruptedException ie) { }
			
			return System.currentTimeMillis();
		}
		
		public void remove() { }
	}
	
	public Iterator<Long> iterator() {
		return new SecondsIterator();
	}
	
}
public class T {

	public static void main(String[] args) {
		for (Long t : new Every(1000))
			System.out.println("tick: "+t);
	}
}

I don't think you understand it immediately but there's nothing wrong with reading the API documentation ;-)

kind regards,

Jos

[camickr]

You can even make a class implement the Iterable interface;

This approach will only work for console apps.

For example you cause the Thread to sleep. This means you can't invoke the code in a GUI because you would cause the GUI to freeze.

I would think managing the Thread yourself is more flexible as you could use the code in a console or GUI app.

[JosAH]

This approach will only work for console apps.

For example you cause the Thread to sleep. This means you can't invoke the code in a GUI because you would cause the GUI to freeze.

I would think managing the Thread yourself is more flexible as you could use the code in a console or GUI app.

Not really; you can always 'lift away' that 'Every' thing from the EDT:

new Thread(new Runnable() {
   public void run() {
      for (Long t : Every(1000))
         // do something every second ...
   }
}).start();

kind regards,

Jos

[camickr]

Not really; you can always 'lift away' that 'Every' thing from the EDT:

Good point!

I did suggest you could create a separate Thread. I should learn to follow my own advice :)

[JosAH]

Good point!

I did suggest you could create a separate Thread. I should learn to follow my own advice :)

:-) Well, it was a bare bones example; maybe a more complete class could do that 'lifting away' from the EDT itself and accept a Runnable for the real work, but on the other hand, I do like the idea of Iterable, i.e. the compiler understands those things ...

kind regars,

Jos