Recursive Node class

Node.java

public class Node {
	int value;
	Node next;

	Node(int value) {
		this.value = value;
	}

	public int get(int index) {
		assert index >= 0 && index < this.length();

		Node node = this;
		while (index-- > 0)
			node = node.next;

		return node.value;
	}

	public void set(int index, int value) {
		assert index >= 0 && index < this.length();

		Node node = this;
		while (index-- > 0)
			node = node.next;

		node.value = value;
	}

	public void append(int value) {
		if (this.hasNext())
			this.next.append(value);
		else
			this.next = new Node(value);
	}

	public boolean hasNext() {
		return this.next != null;
	}

	public boolean includes(int value) {
		for (Node node = this; node != null; node = node.next)
			if (node.value == value)
				return true;
		return false;
	}

	public int sum() {
		if (this.hasNext())
			return this.value + this.next.sum();
		return this.value;
	}

	public int length() {
		if (this.hasNext())
			return 1 + this.next.length();
		return 1;
	}

	@Override
	public String toString() {
		if (this.hasNext())
			return this.value + ", " + this.next.toString();
		return String.valueOf(this.value);
	}
}