数据结构--链表的实现

public class LinkList {

class Node<E> {
    private E e;
    private Node next;
    
    public Node(E e, Node next) {
        this.e = e;
        this.next = next;
    }
    
    public Node(E e) {
        this(e, null);
    }
    
    public Node() {
        this(null, null);
    }
}

//链表元素数量
private int size;
//定义一个头节点
private Node head;

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

//获取链表元素数量 
public int getSize() {
    return size;
}

//判断链表是否为空
public boolean isEmpty() {
    return size == 0;
}

//在链表头部添加元素
public void pushFirst(E e) {
    Node node = new Node(e);
    node.next = head;
    head = node;
    size++;
}

//在链表指定位置添加元素1->2->3->4
public void push(int index, E e) {
    if(index < 0 || index > size)
       throw new IllegalArgumentException("索引越界");
    if(index == 0) {
        //在链表头部添加元素
        pushFirst(e);
    }else{
        Node prev = head;
        for(int i = 0; i < size - 1; i ++) {
            prev = prev.next;
        }
        Node newNode = new Node(e);
        newNode.next = prev.next;
        prev.next = newNode;
        size++;
    }
    
}

//在链表尾部添加元素
public void pushLast(E e) {
    push(size, e);
}

@Override
public String toString() {
    Node tail = head;
    StringBuilder stringBuilder = new StringBuilder();
    stringBuilder.append("链表：[");
    while(tail.next != null) {
        stringBuilder.append(tail.e).append("->");
        tail = tail.next;
    }
    stringBuilder.append(tail.e).append("]");
    return stringBuilder.toString();
}

}