LinkedList_JAEKWANG97.java

package List.LinkedList;

import List.List;

public class LinkedList_JAEKWANG97<E> implements List<E> {

    static class Node<E> {
        E data;
        Node<E> next;
        Node<E> prev;

        public Node(E data) {
            this.data = data;
            this.next = null;
            this.prev = null;
        }
    }

    private Node<E> head;
    private Node<E> tail;
    private int size;

    public LinkedList_JAEKWANG97() {
        this.head = null;
        this.tail = null;
        this.size = 0;
    }

    @Override
    public void insert(E data) {
        Node<E> newNode = new Node<>(data);
        if (head == null) {
            head = newNode;
            tail = newNode;
        } else {
            tail.next = newNode;
            newNode.prev = tail;
            tail = newNode;
        }
        size++;
    }

    @Override
    public int size() {
        return size;
    }

    @Override
    public boolean isEmpty() {
        return size == 0;
    }

    @Override
    public boolean contains(E o) {
        if (isEmpty()) {
            return false;
        }
        Node<E> cur = head;
        while (cur != null) {
            if (cur.data == o) {
                return true;
            }
            cur = cur.next;
        }

        return false;
    }

    @Override
    public E get(int index) {
        if (index < 0 || index >= size) {
            throw new IndexOutOfBoundsException();
        }
        Node<E> cur = head;
        for (int i = 0; i < index; i++) {
            cur = cur.next;
        }
        return cur.data;
    }

    @Override
    public E remove(int index) {
        if (index < 0 || index >= size) {
            throw new IndexOutOfBoundsException();
        }
        Node<E> cur = head;
        for (int i = 0; i < index; i++) {
            cur = cur.next;
        }
        cur.prev.next = cur.next;
        cur.next.prev = cur.prev;
        size--;
        return cur.data;
    }
}