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    <p><a href="http://bradforj287.blogspot.com/2010/11" rel="nofollow">Efficient Circular Buffer in Java</a></p> <p>Overwriting Circular buffers are great data structures to use if you would like to operate on a recent window of data. Elements are added and removed FIFO like a Queue, except additions on full buffers will cause the oldest (head of the queue) element to be removed. </p> <pre><code>import java.util.NoSuchElementException; /** * Thread safe fixed size circular buffer implementation. Backed by an array. * * @author brad */ public class ArrayCircularBuffer&lt;T&gt; { // internal data storage private T[] data; // indices for inserting and removing from queue private int front = 0; private int insertLocation = 0; // number of elements in queue private int size = 0; /** * Creates a circular buffer with the specified size. * * @param bufferSize * - the maximum size of the buffer */ public ArrayCircularBuffer(int bufferSize) { data = (T[]) new Object[bufferSize]; } /** * Inserts an item at the end of the queue. If the queue is full, the oldest * value will be removed and head of the queue will become the second oldest * value. * * @param item * - the item to be inserted */ public synchronized void insert(T item) { data[insertLocation] = item; insertLocation = (insertLocation + 1) % data.length; /** * If the queue is full, this means we just overwrote the front of the * queue. So increment the front location. */ if (size == data.length) { front = (front + 1) % data.length; } else { size++; } } /** * Returns the number of elements in the buffer * * @return int - the number of elements inside this buffer */ public synchronized int size() { return size; } /** * Returns the head element of the queue. * * @return T */ public synchronized T removeFront() { if (size == 0) { throw new NoSuchElementException(); } T retValue = data[front]; front = (front + 1) % data.length; size--; return retValue; } /** * Returns the head of the queue but does not remove it. * * @return */ public synchronized T peekFront() { if (size == 0) { return null; } else { return data[front]; } } /** * Returns the last element of the queue but does not remove it. * * @return T - the most recently added value */ public synchronized T peekLast() { if (size == 0) { return null; } else { int lastElement = insertLocation - 1; if (lastElement &lt; 0) { lastElement = data.length - 1; } return data[lastElement]; } } } </code></pre>
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    1. POSingle Item Producer-Consumer. Which datastructure can I use in Java?
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