Buffer with five elements Java

Question

What is the best way to create some construction with exactly five elements and when I try to put another one to remove the firstone etc ?

Im wonderoing what construction should I use ? ArrayList or HashMap witch is the best way to handle it ? — Boris Pawlowski, Jul 29 '14 at 12:38
Any of the lists would do (probably an arraylist) or an array itself. Then wrap it in an object that performs the function you desire — Richard Tingle, Jul 29 '14 at 12:40
people keep complaining that we are rude, but there you go. What can we understand from this question? We need a "Mind reading" functionality in this site — Sleiman Jneidi, Jul 29 '14 at 12:40
Possible duplicate of [Java - Ring Buffer](http://stackoverflow.com/questions/7266042/java-ring-buffer) — DavidPostill, Jul 29 '14 at 12:44
You want a FIFO structure of at most ( elements. Try reading this: http://stackoverflow.com/questions/9580457/fifo-class-in-java — StephaneM, Jul 29 '14 at 12:45

score 1 · Answer 1 · answered Jul 29 '14 at 12:40

1

I would just recommend you an ArrayList It is very easy to Handle and the Remove/Add Operations are available

answered Jul 29 '14 at 12:40

romaneso

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Vincent Mimoun-Prat · Answer 2 · 2014-07-29T12:46:37.223

0

Queue is the LIFO object you need.

If you are a Apache fan, you have CircularFifoQueue
If you are more into Guava, you have EvictingQueue
You can also do it yourself: (LinkedList is one implementation amongst others)

`

// Create
Queue q = new LinkedList();

// Insert 
void safeInsert(Queue q, Object elt) {
  if (q.size()>=5) {
    q.poll();
  }
  q.offer(elt);
}

edited Jul 29 '14 at 12:46

answered Jul 29 '14 at 12:41

Vincent Mimoun-Prat

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score 0 · Answer 3 · answered Jul 29 '14 at 12:41

0

The CircularFifoQueue provided by Apache Commons Collections does what you need.

answered Jul 29 '14 at 12:41

Brent Worden

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score 0 · Answer 4 · edited May 23 '17 at 12:20

0

What you are asking for is called a circular buffer or ring buffer.

The Java library does not provide an implementation for you (confirmed, confirmed again), so you will have to write one yourself, or use a third-party library.

edited May 23 '17 at 12:20

Community

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answered Jul 29 '14 at 12:41

Raedwald

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achingfingers · Answer 5 · 2014-07-29T12:45:05.560

0

I am not sure whether this is the "best solution", but it's quite simple and does exactly what you want:

List<Foo> list = new ArrayList<>();
...

list.add(item);
if(list.size()>5){
 list.remove(0);
}

edited Jul 29 '14 at 12:45

answered Jul 29 '14 at 12:41

achingfingers

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score 0 · Answer 6 · answered Jul 29 '14 at 12:42

public class MyArrayList extends ArrayList<Object>{

    private static final int MAX_SIZE = 5;

    @Override
    public void add(int index, Object object) {

        if(this.size() == MAX_SIZE)
            this.remove(0);
        super.add(MAX_SIZE -1, object);
    }

    @Override
    public boolean add(Object object) {

        if(this.size() == MAX_SIZE)
            this.remove(0);
        return super.add(object);
    }

    @Override
    public boolean addAll(Collection<? extends Object> collection) {
        throw new SomeException();
    }

    @Override
    public boolean addAll(int index, Collection<? extends Object> collection) {
        throw new SomeException();
    }

}

Buffer with five elements Java

6 Answers6