Java integer list

Question

I am trying to make java go trough a list of numbers. It chooses the first one, gives this as output, waits/sleeps like 2000 milliseconds and then give the next one as output, waits 2000 milliseconds, etc.

They should not be listed behind eachother so when my list is: 10 20 30 40 50

It should not give as output: 10 20 30 40 50. But just 50.

It would be even better if it was able to repeat itself.

So far i tried:

List<Integer> myCoords = new ArrayList<Integer>();
myCoords.add(10);
myCoords.add(20);
myCoords.add(30);
myCoords.add(40);
myCoords.add(50);
Iterator<Integer> myListIterator = someList.iterator(); 
while (myListIterator.hasNext()) {
    Integer coord = myListIterator.next();     
}

But this has no timer, and i am not sure if this will only show '20' or '10 20 30 40 50' as output. And i dont really know how to put a sleep/wait command and a repeat command in this :s (might have overlooked the repeat command if its already in)

Edit Tyvm all, i can go on with the rest of the coding now :)

In addition, you contradict yourself. First you say It chooses the first one, gives this as output, ... and then give the next one as output then later It should not give as output: 10 20 30 40 50. But just 50. — Brian Roach
– Brian Roach, Commented Mar 20, 2011 at 21:47
@Brian Roach he means it rewinds and rewrites the line. (\r) — alternative
– alternative, Commented Mar 20, 2011 at 21:51
@mathepic - Impressive, I could not have pulled that from the question without you pointing it out. — Brian Roach
– Brian Roach, Commented Mar 20, 2011 at 21:57

Messa · Accepted Answer · 2011-03-20 21:59:43Z

27

If you want to rewrite a line on console, print a control character \r (carriage return).

List<Integer> myCoords = new ArrayList<Integer>();
myCoords.add(10);
myCoords.add(20);
myCoords.add(30);
myCoords.add(40);
myCoords.add(50);
Iterator<Integer> myListIterator = myCoords.iterator(); 
while (myListIterator.hasNext()) {
    Integer coord = myListIterator.next();     
    System.out.print("\r");
    System.out.print(coord);
    Thread.sleep(2000);
}

answered Mar 20, 2011 at 21:59

Messa

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2 Comments

Zen Over a year ago

this might be late but,i just for started with list. Whats the difference between using a for loop like; for(i<list.size();i++) and a while loop with hasNext()?

Messa Over a year ago

@alexsummers It is just a different method of accessing collection elements. See stackoverflow.com/questions/99164/… and stackoverflow.com/questions/89891/…

dantuch · Accepted Answer · 2011-03-20 22:13:47Z

2

code that works, but output is:

so:

    List<Integer> myCoords = new ArrayList<Integer>();
    myCoords.add(10);
    myCoords.add(20);
    myCoords.add(30);
    myCoords.add(40);
    myCoords.add(50);
    for (Integer number : myCoords) {
        System.out.println(number);
        try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

edited Mar 20, 2011 at 22:13

answered Mar 20, 2011 at 21:57

dantuch

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Comments

Blackcom · Accepted Answer · 2011-03-20 21:51:48Z

1

To insert a sleep command you can use Thread.sleep(2000). So the code would be:

List<Integer> myCoords = new ArrayList<Integer>();
myCoords.add(10);
myCoords.add(20);
myCoords.add(30);
myCoords.add(40);
myCoords.add(50);
Iterator<Integer> myListIterator = someList.iterator(); 
while (myListIterator.hasNext()) {
    Integer coord = myListIterator.next();    
    System.out.println(coord);
    Thread.Sleep(2000);
}

This would output: 10 20 30 40 50

If you want the numbers after each other you could use: System.out.print(coord +" " ); and if you want to repeat the section you can put it in another while loop.

List<Integer> myCoords = new ArrayList<Integer>();
myCoords.add(10);
myCoords.add(20);
myCoords.add(30);
myCoords.add(40);
myCoords.add(50);
while(true)
    Iterator<Integer> myListIterator = someList.iterator(); 
    while (myListIterator.hasNext()) {
        Integer coord = myListIterator.next();    
        System.out.print(coord + " ");
        Thread.Sleep(2000);
    }
}

This would output: 10 20 30 40 50 10 20 30 40 50 ... and never stop until you kill the program.

Edit: You do have to put the sleep command in a try catch block

answered Mar 20, 2011 at 21:51

Blackcom

1466 bronze badges

5 Comments

JJ90 Over a year ago

So what i change in that piece of code to make it just rewrite the previous number? something with the System.out.print(coord + " "); ? And 'try catch block' ? That string looks ok for me in the way u just wrote it :P

JJ90 Over a year ago

AH, so like: try{ Thread.sleep(2000); }catch(Exception e){ // handle the exception... }; instead of Thread.Sleep(2000);

JJ90 Over a year ago

About the rewrite, or did u mean it is rewriting its previous output?

MByD Over a year ago

'try and catch block' is relevant here because the method sleep may throw an exception. You can learn about it more here: download.oracle.com/javase/tutorial/essential/exceptions

JJ90 Over a year ago

Ah so it would become: (see my 2nd post in this question)

Jónás Balázs · Accepted Answer · 2018-12-17 12:05:26Z

1

Let's use some java 8 feature:

IntStream.iterate(10, x -> x + 10).limit(5)
  .forEach(System.out::println);

If you need to store the numbers you can collect them into a collection eg:

List numbers = IntStream.iterate(10, x -> x + 10).limit(5)
  .boxed()
  .collect(Collectors.toList());

And some delay added:

IntStream.iterate(10, x -> x + 10).limit(5)
  .forEach(x -> {
    System.out.println(x);
    try {
      Thread.sleep(2000);
    } catch (InterruptedException e) {
      // Do something with the exception
    }  
  });

answered Dec 17, 2018 at 12:05

Jónás Balázs

80911 silver badges27 bronze badges

Comments

JJ90 · Accepted Answer · 2011-03-20 22:24:46Z

0

So it would become:

List<Integer> myCoords = new ArrayList<Integer>();
myCoords.add(10);
myCoords.add(20);
myCoords.add(30);
myCoords.add(40);
myCoords.add(50);
while(true)
    Iterator<Integer> myListIterator = myCoords.iterator(); 
    while (myListIterator.hasNext()) {
        Integer coord = myListIterator.next();    
        System.out.print("\r" + coord);
        try{
    Thread.sleep(2000);
  }catch(Exception e){
   // handle the exception...
  }
    }
}

edited Mar 20, 2011 at 22:24

answered Mar 20, 2011 at 22:09

JJ90

2531 gold badge2 silver badges5 bronze badges

5 Comments

Messa Over a year ago

To remove previous outcome: System.out.print("\r" + coord);

JJ90 Over a year ago

:O, hmm.. how else can i make it rewrite the previous outcome u think?

JJ90 Over a year ago

with System.out.print(coord + " "); instead of the System.out.print("\r" + coord); perhaps?

dantuch Over a year ago

and not someList. but your list - means -> ` Iterator<Integer> myListIterator = myCoords.iterator(); `

Messa Over a year ago

What operating system are you using and where are you printing to? "\r" works on Linux/Mac terminal (tested) and should work in Windows console. But if you are looking at the output in some IDE (NetBeans, Eclipse) then it might not work.

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