SLLC.java

import java.util.NoSuchElementException;

public class SLLC {
    NodeSLLC head, tail;
    int size;

    SLLC() {
        head = tail = null;
        size = 0;
    }

    boolean isEmpty() {
        return size == 0;
    }

    void addFirst(NodeSLLC input) {
        if (isEmpty()) {
            head = tail = input;
            tail.next = head;
        }
        else {
            input.next = head;
            tail.next = input;
            head = input;
        }
        size++;
    }

    void addLast(NodeSLLC input) {
        if (isEmpty()) {
            head = tail = input;
            tail.next = head;
        }
        else {
            tail.next = input;
            input.next = head;
            tail = input;
        }
        size++;
    }

    void removeFirst() {
        if (!isEmpty()) {
            if (size == 1) head = tail = null;
            else {
                NodeSLLC temp = head.next;
                tail.next = temp;
                head = temp;
            }
            size--;
        }
        else throw new NoSuchElementException();
    }

    void removeLast() {
        if (!isEmpty()) {
            if (size == 1) head = tail = null;
            else {
                NodeSLLC temp = head;
                while (temp.next != tail) {
                    temp = temp.next;
                }
                temp.next = head;
                tail = temp;
            }
            size--;
        }
        else throw new NoSuchElementException();
    }

    private void checkIndex(int index) {
        if (index < 0 || index >= size) throw new IndexOutOfBoundsException();
    }

    Object get(int index) {
        checkIndex(index);
        NodeSLLC temp = head;
        for (int i = 0; i < index; i++) temp = temp.next;
        return temp.data;
    }

    @Override
    public String toString() {
        NodeSLLC p = head;
        String s = "[";
        for (int i = 0; i < size; i++) {
            if (i != 0) s += ", ";
            s += p.data;
            p = p.next;
        }
        s += "]";
        return s;
    }
}