Are there any unordered, repeatable Collection classes in Java?
<p>I want a collection contains unordered, repeatable items.
In Java, Set is unrepeatable, List is ordered, which are not what I want.</p>

<p>It seems Pool is an appropriate collection, but it doesn't exist in Java.
The interface should be as following:</p>

<pre><code>public interface Pool&lt;T&gt; {
    void set(T item);
    T get();
}
</code></pre>

<p>Does it exist somewhere?</p>

<hr>

<p><strong>Complementing：</strong></p>

<p>I realize that I expressed my thought incorrectly. Infact, I want to have an interface like this:</p>

<pre><code>public interface Pool&lt;T&gt; {
    void put(T item);
    T randomRemove();
}
</code></pre>

<p>That is to say, I want to get an item ramdomly everytime. How can I achieve it?</p>