SimpleQueue.java

import java.util.LinkedList;

/**
 * Simple Queue (FIFO) based on LinkedList.
 */
public class SimpleQueue<E> {

  private LinkedList<E> list = new LinkedList<E>();

  /**
   * Puts object in queue.
   */
  public void put(E o) {
    list.addLast(o);
  }

  /**
   * Returns an element (object) from queue.
   *
   * @return element from queue or <code>null</code> if queue is empty
   */
  public E get() {
    if (list.isEmpty()) {
      return null;
    }
    return list.removeFirst();
  }

  /**
   * Returns all elements from the queue and clears it.
   */
  public Object[] getAll() {
    Object[] res = new Object[list.size()];
    for (int i = 0; i < res.length; i++) {
      res[i] = list.get(i);
    }
    list.clear();
    return res;
  }

  /**
   * Peeks an element in the queue. Returned elements is not removed from the queue.
   */
  public E peek() {
    return list.getFirst();
  }

  /**
   * Returns <code>true</code> if queue is empty, otherwise <code>false</code>
   */
  public boolean isEmpty() {
    return list.isEmpty();
  }

  /**
   * Returns queue size.
   */
  public int size() {
    return list.size();
  }
}