手写简易链表

直接上代码

package com.mydemo.writeCases;

/**
 * 简易链表手写实现
 * @param <E>
 */
public class ILinkedList<E> {
    //节点类
    private class INode{
        //当前节点的值
        private E e;
        //指针,指向下一个节点
        private INode next;

        //构造方法
        public INode(){
        }
        public INode(E e){
            this.e = e;
        }
        public INode(E e,INode next){
            this.e = e;
            this.next = next;
        }

        @Override
        public String toString(){
            //"null"处理主要是防止dummyHead.toString被调用抛出空指针(比如IDEA默认dubug时会调用)
            return this.e == null ? "null" : this.e.toString();
        }
    }

    //虚拟头结点(使用虚拟节点的好处可以自行百度)
    private INode dummyHead;
    //长度
    private int size;
    //构造方法
    public ILinkedList(){
        this.dummyHead = new INode();
        this.size = 0;
    }
    //返回链表长度
    public int getSize(){
        return this.size;
    }

    //指定索引添加元素
    public void add(E e, int index) {
        if (index < 0 || index > size) {
            throw new IndexOutOfBoundsException("角标越界");
        }
        INode prev = this.dummyHead;
        for (int i = 0; i < index; i++) {
            prev = prev.next;
        }
        prev.next = new INode(e,prev.next);
        size++;
    }

    public void addFirst(E e){
        this.add(e,0);
    }
    public void addLast(E e){
        this.add(e,size);
    }

    //删除元素
    public E remove(int index){
        if (index < 0 || index >= size) {
            throw new IndexOutOfBoundsException("角标越界");
        }
        INode prev = this.dummyHead;
        for (int i = 0; i < index; i++) {
            prev = prev.next;
        }
        //获取目标节点
        INode targetNode = prev.next;
        //重指向
        prev.next = targetNode.next;;
        //删除引用关联
        targetNode.next = null;
        size--;
        return targetNode.e;

    }

    public E removeFirst(){
        return remove(0);
    }

    public E removeLast(){
        return remove(size-1);
    }

    //按索引获取元素
    public E get(int index) {
        if (index < 0 || index >= size) {
            //注意index=size时的情况
            throw new IndexOutOfBoundsException("角标越界");
        }
        INode prev = this.dummyHead;
        for (int i = 0; i < index; i++) {
            prev = prev.next;
        }
        return prev.next.e;

    }

    public E getFirst(){
        return get(0);
    }
    public E getLast(){
        return get(size-1);
    }

    //set方法
    public void set(E e,int index){
        if (index < 0 || index >= size) {
            //注意index=size时的情况
            throw new IndexOutOfBoundsException("角标越界");
        }
        INode prev = this.dummyHead;
        for (int i = 0; i < index; i++) {
            prev = prev.next;
        }
        prev.next.e = e;
    }

    //contains方法
    public boolean contains(E e) {
        INode cur = dummyHead.next;
        while (cur != null) {
            if (cur.e.equals(e)) {
                return true;
            }
            cur = cur.next;
        }
        return false;
    }

    @Override
    public String toString(){
        StringBuilder stringBuilder = new StringBuilder("");
        for (INode cur = dummyHead.next; cur != null; cur = cur.next) {
            stringBuilder.append("[" + cur + "]");

        }
        return stringBuilder.toString();
    }
}