简单实现LinkedList(双向链表)

古城微笑少年丶 2022-06-16 02:59 206阅读 0赞

看源码和视频自己写了写,当然和源码差了n个数量级. 也算复习了下链表

SetLinkedList类

package cn.hjy.collection;
    
    import java.util.List;
    /** * @author 543363559@qq.com * @date 2017年4月30日 下午4:47:34 */
    public class SetLinkedList { 
        private Node first;
        private Node last;
    
        private int size;
    /** * * @Description: 添加结点 建first or 往last.next添加 * @param @param obj * @param @return * @return boolean */
        public boolean add(Object obj){
            Node n = new Node();
            if(first == null){
                n.setPrevious(null);
                n.setObj(obj);
                n.setNext(null);
    
                first = n;
                last = n;
            } else {
                //直接往last结点后增加新的结点
                n.setPrevious(last);
                n.setObj(obj);
                n.setNext(null);
    
                last.setNext(n);
    
                last = n;
            }
            size++;
            return true;
        }
    /** * * @Description: 返回链表大小 * @param @return * @return int */
        public int size(){
            return size;
        }
    /** * * @Description: 删除指定索引位置对象 * @param @param index * @return void */
        public void remove(int index){
            //得到结点
            Node temp = node(index);
    
            if (temp != null) {
                Node up = temp.getPrevious();
                Node down = temp.getNext();
                up.setNext(down);
                if (down != null) {
                    down.setPrevious(up);
                }
            } 
            size--;
        }
    /** * * @Description: 获得想要位置的结点 * @param @param index * @param @return * @return Node */
        public Node node(int index) {
            Node temp = null;
            if (first != null) {
                temp = first;
                for (int i = 0; i < index; i++) {
                    temp = temp.getNext();
                }
            }
            return temp;
        }
    /** * * @Description: 得到index的obj值 * @param @param index * @param @return * @return Object */
        public Object get(int index){
            rangeCheck(index); //越界处理
    
            Node temp = node(index);
            if (temp != null) {
                return temp.getObj();           
            } else {
                return null;
            }
        }
    /** * * @Description: 在链表index位置添加结点 * @param @param index * @param @param obj * @return void */
        public void add(int index,Object obj) {
            Node temp = node(index);
    
            Node newNode = new Node();
            newNode.setObj(obj);
    
            if (temp != null) {
                Node up = temp.getPrevious();
                up.setNext(newNode);
                newNode.setPrevious(up);
    
                newNode.setNext(temp);
                temp.setPrevious(newNode);
            }
            size++;
        }
    /** * * @Description: 修改链表中 index的obj * @param @param index * @param @param obj * @return void */
        public void set(int index,Object obj) {
            Node temp = node(index);
            if (temp != null) {
                temp.setObj(obj);
            }
        }
    /** * * @Description: 判断index是否超出链表范围,超出则抛出异常 * @param @param index * @return void */
        private void rangeCheck(int index) {
            if (index < 0 || index >= size) {
                try {
                    throw new Exception();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
    /** * * @Description: 遍历显示 * @param * @return void */
        public void show() {
            Node temp = new Node();
            if (first != null) {
                temp = first;
                while (temp != null) {
                    System.out.print(temp.getObj() + " ");
                    temp = temp.getNext();
                }
            }
    
        }
        public SetLinkedList() { 
    
        }
    
        public static void main(String[] args) {
            SetLinkedList list = new SetLinkedList();
            list.add("aaa");
            list.add("bbb");
    
            list.add(1, "www");
            System.out.println(list.get(1)); //www
            list.set(1, "qqq");
            System.out.println(list.get(1)); //qqq
            list.remove(1);
            System.out.println(list.get(1)); //bbb
            list.show(); //aaa bbb
            System.out.println(list.size()); //2
        }
    
    }

Node类

package cn.hjy.collection;
    
    class Node {
        private Node previous;
        private Object obj;
        private Node next;
    
        Node(){
    
        }
    
        public Node(Node previous, Object obj, Node next) {
            super();
            this.previous = previous;
            this.obj = obj;
            this.next = next;
        }
    
    
    
        public Node getPrevious() {
            return previous;
        }
    
        public void setPrevious(Node previous) {
            this.previous = previous;
        }
    
        public Object getObj() {
            return obj;
        }
    
        public void setObj(Object obj) {
            this.obj = obj;
        }
    
        public Node getNext() {
            return next;
        }
    
        public void setNext(Node next) {
            this.next = next;
        }
    
    
    
    }