Circular Buffer : Array Basics « Collections « Java Tutorial

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public class TestCircularBuffer {
  public static void main(String args[]) {
    TestCircularBuffer t = new TestCircularBuffer();
  }

  public TestCircularBuffer() {
    CircularBuffer c = new CircularBuffer(8);

    System.out.println("Storing: 1");
    c.store(1);
    System.out.println("Reading: " + c.read());
    System.out.println("Storing: 2");
    c.store(2);
    System.out.println("Storing: 3");
    c.store(3);
    System.out.println("Storing: 4");
    c.store(4);
    System.out.println("Reading: " + c.read());
    System.out.println("Reading: " + c.read());
    System.out.println("Storing: 8");
    c.store(8);
    System.out.println("Storing: 9");
    c.store(9);
    System.out.println("Storing: 10");
    c.store(10);
    System.out.println("Storing: 11");
    c.store(11);
    System.out.println("Storing: 12");
    c.store(12);
    System.out.println("Reading: " + c.read());
    System.out.println("Reading: " + c.read());
    System.out.println("Reading: " + c.read());
    System.out.println("Reading: " + c.read());
    System.out.println("Reading: " + c.read());
    System.out.println("Reading: " + c.read());
    System.out.println("Reading: " + c.read());
    System.out.println("Reading: " + c.read());
  }
}

class CircularBuffer {
  private Integer data[];
  private int head;
  private int tail;

  public CircularBuffer(Integer number) {
    data = new Integer[number];
    head = 0;
    tail = 0;
  }

  public boolean store(Integer value) {
    if (!bufferFull()) {
      data[tail++] = value;
      if (tail == data.length) {
        tail = 0;
      }
      return true;
    } else {
      return false;
    }
  }

  public Integer read() {
    if (head != tail) {
      int value = data[head++];
      if (head == data.length) {
        head = 0;
      }
      return value;
    } else {
      return null;
    }
  }

  private boolean bufferFull() {
    if (tail + 1 == head) {
      return true;
    }
    if (tail == (data.length - 1) && head == 0) {
      return true;
    }
    return false;
  }
}