自己实现LinkedList

JDK中的LinkedList 里的属性

Node  first ;

Node last ;

int size;

在源码中的查找，用到了二分查找，先判断要查找的索引值index,和size比较大小，再判断是从first节点还是last节点开始查找

自己实现的LinkedList

public class MyLinkedList {
    
    // 链表查询的开始节点
    private Node first;

    // 链表默认从末尾节点开始添加新的节点
    private Node last;

    //当前节点的个数
    private int size;

    public void add(Object obj) {
        Node newNode = new Node();
        newNode.value = obj;
        if (first == null) {
            first = newNode;
            last = newNode;
        } else {
            last.next = newNode;
            newNode.prev = last;
            last = newNode;
        }
        size++;
    }

    public void remove(int index) {
        checkElementIndex(index);
        if (index == 0) { // 第一个节点
            first = first.next;
            if (first != null)
                first.prev = null;
        } else if (index == size - 1) { // 最后一个节点
            last = last.prev;
            last.next = null;
        } else {
            Node current = getNode(index);
            Node node1 = current.prev;
            Node node3 = current.next;
            node1.next = node3;
            node3.prev = node1;
        }
        size--;
    }

    public Node getNode(int index) {
        Node node = first;
        for (int i = 0; i < index; i++) {
            node = node.next;
        }
        return node;
    }

    public Object get(int index) {
        checkElementIndex(index);
        return getNode(index).value;
    }

    public int getSize() {
        return size;
    }

    public static void main(String[] args) {
        MyLinkedList myLinkedList = new MyLinkedList();
        myLinkedList.add("A");
        myLinkedList.add("B");
        myLinkedList.add("C");
        myLinkedList.add("D");
        myLinkedList.remove(2);
        for (int i = 0; i < myLinkedList.getSize(); i++) {
            System.out.println(myLinkedList.get(i));
        }

    }

    private void checkElementIndex(int index) {
        if (!isElementIndex(index))
            throw new IndexOutOfBoundsException("查询越界啦！");
    }

    private boolean isElementIndex(int index) {
        return index >= 0 && index < size;
    }

    private class Node {
        Node prev;
        Node next;
        Object value;
    }
}