Implementing a Ring Buffer in Java for Time Series Data

What is the best Java collection to use for implementing a ring buffer to maintain the last 4 elements of a streaming time series?

// Java code snippet for a ring buffer implementation
import java.util.LinkedList;
import java.util.Queue;

public class RingBuffer<T> {
    private final Queue<T> buffer;
    private final int capacity;

    public RingBuffer(int capacity) {
        this.capacity = capacity;
        this.buffer = new LinkedList<>();
    }

    public void add(T element) {
        if (buffer.size() == capacity) {
            buffer.poll(); // Remove the oldest element
        }
        buffer.offer(element); // Add the new element
    }

    public Queue<T> getElements() {
        return new LinkedList<>(buffer); // Return a copy of the buffer
    }
}

A ring buffer is an essential data structure used for managing a fixed-size buffer that allows for efficient push and pop operations, especially useful in scenarios like time series streaming where only the most recent elements are required. In Java, while there are several collection types available, using a `LinkedList` or array-based custom implementation is typically best for creating a ring buffer.

// Example usage of the RingBuffer class
public class Main {
    public static void main(String[] args) {
        RingBuffer<Integer> ringBuffer = new RingBuffer<>(4);
        ringBuffer.add(1);
        ringBuffer.add(2);
        ringBuffer.add(3);
        ringBuffer.add(4);
        ringBuffer.add(5); // This will remove '1'

        System.out.println(ringBuffer.getElements()); // Should print [2, 3, 4, 5]
    }
}

Causes

• Efficiency in maintaining a fixed number of elements.
• Need for FIFO (first-in-first-out) behavior for a streaming series.

Solutions

• Use `LinkedList` for dynamic resizing and easier element additions/removals.
• Create a custom class for better control over behavior, using an array for fixed size.

Mistake: Choosing `Vector` for a ring buffer due to its synchronization features, which are not needed for this use case.

Solution: Instead, use `ArrayList` or `LinkedList` for better performance.

Mistake: Not handling the capacity correctly which may lead to an unexpected growth of the buffer size.

Solution: Implement checks to ensure the buffer remains fixed in size.