链表的实现 LinkedList （Java实现）

实现代码

public class LinkedList<E>{
	
	// 内部类
	private class Node{
		private E e;
		private Node next;
		public void Node(E e, Node next){
			this.e = e;
			this.next = next;
		}
		public Node(E e){
			this(e, next);
		}
		public Node(){
			this(null, null);
		}
		
		public String toString(){
			return e.toString;
		}
	}
	
	// 虚拟的头结点
	private Node dummyhead;
	private int size;

	public LinkedList(){
		dummyhead = new Node(null, null);
		size = 0;
	}
	
	// 获取链表的元素个数
	public int getSize(){
		return size;
	}
	// 判断链表是否为空
	public boolean isEmpty(){
		return (size == 0);
	}

	// 插入元素
	public void add(int index, E e){
		if (index < 0 || index > size){
            throw new IllegalArgumentException("Add failed, Illegal index.");
        }

		Node pre = dummyhead;
		for (int i = 0, i < index, i++){
			pre = pre.next;
		}
		Node node = new Node(e);
		node.next = pre.next;
		pre.next = node;

		size ++;
	}

	// 在链表的头部添加新的元素
    public void addFirst(E e){
        add(0, e);
    }

    // 在链表的尾部添加节点
    public void addLast(E e){
        add(size ,e);
    }

	// 获得链表的index的元素
	public E get(int index){
		if (index < 0 || index > size){
            throw new IllegalArgumentException("Get failed, Illegal index.");
        }
		
		Node cur = dummyNode.next;
		if (int i = 0; i < index; i++){
			cur = cur.next;
		}
		return cur.next;
	}
	
 	//获得链表的第一个元素
    public E getFirst(){
        return get(0);
    }
    // 获得最后一个元素
    public E getLast(){
        return get(size - 1);
    }
	
	// 修改链表index的元素
	public void set(int index){
		 if (index < 0 || index > size){
            throw new IllegalArgumentException("Set failed, Illegal index.");
        }
         Node cur = dummyhead.next;
        for (int i = 0; i < index; i++){
            cur = cur.next;
        }
        cur.e = e;
	}
	
	// 查找链表中是否存在e
    public boolean contains(E e){
        Node cur = dummyhead.next;
        while (cur != null){
            if (cur.e == e){
                return true;
            }
            cur = cur.next;
        }
        return false;
    }

    // 链表的删除
    public E delete(int index){
        if (index < 0 || index > size){
            throw new IllegalArgumentException("Delete failed, Illegal index.");
        }

        Node pre = dummyhead;
        for (int i = 0; i < index; i++){
            pre = pre.next;
        }
        Node ret = pre.next;
        pre.next = ret.next;
        ret.next = null;
        size --;
        return ret.e;
    }

    // 删除第一个元素
    public E removeFirst(){
        return delete(0);
    }

    // 删除最后一个元素
    public E removeLast(){
        return delete(size - 1);
    }

    @Override
    public String toString(){
        StringBuilder sb = new StringBuilder();
        Node cur = dummyhead.next;
        while (cur != null){
            sb.append(cur+"->");
            cur = cur.next;
        }
        sb.append("NULL");
        return sb.toString();
    }

}

测试类

public class Main {
    public static void main(String[] args){
        LinkedList<Integer> linkedList = new LinkedList<>();
        for(int i = 0 ; i < 5 ; i ++){
            linkedList.addFirst(i);
            System.out.println(linkedList);
        }

        linkedList.add(2, 666);
        System.out.println(linkedList);

        linkedList.delete(2);
        System.out.println(linkedList);
    }
}