Collection with limit and ability to remove old items before add new, if limit is reached

Question

Who knows a collection with limit and ability to remove old items before add new, if limit is reached?

Old are the entries, which were placed at the beginning.

Answer 1

You should use org.apache.commons.collections4.queue.CircularFifoQueue from Apache Commons Collections with its constructor CircularFifoQueue(final int size).

CircularFifoQueue is a first-in first-out queue with a fixed size that replaces its oldest element if full. The removal order of a CircularFifoQueue is based on the insertion order; elements are removed in the same order in which they were added. The iteration order is the same as the removal order.

Example:

class Test {
    public static void main(String[] args) {
        Queue<Integer> numbers = new CircularFifoQueue<>(2);
        for (int i = 0; i < 4; i++) {
            numbers.add(i);
            System.out.println("Iteration#" + i + " : " + numbers);
        }
    }
}

// Output:
// Iteration#0 : [0]
// Iteration#1 : [0, 1]
// Iteration#2 : [1, 2]
// Iteration#3 : [2, 3]