【数据结构】链表的实现 之 带头循环单链表的实现

接口方法：

public interface ICLinked    {
    //头插法
    void addFirst(int data);
    //尾插法
    void addLast(int data);
    //任意位置插入,第一个数据节点为0号下标
    boolean addindex(int index,int data);
    //查找是否包含关键字key是否在单链表当中
    boolean contains(int key);
    //删除第一次出现关键字为key的节点
    int remove(int key);
    //删除所有值为key的节点
    void removeAllKey(int key);
    //得到单链表的长度
    int getLength();
    void display();
    void clear();
}

实现接口及方法重写：

public class HeadSingleLinkedListImpl implements ICLinked {

    class Node{
        private  int data;
        private Node next;

        //头结点
        public Node(){
            this.data = -1;
        }
        //数据节点
        public Node (int data){
            this.data = data;
        }
    }
    private  Node head;
    public HeadSingleLinkedListImpl() {
        this.head = new Node();
        this.head.next = this.head;
    }

    @Override
    public void addFirst(int data) {
        Node node = new Node(data);
        node.next = this.head.next;
        this.head.next = node;
    }

    @Override
    public void addLast(int data) {
        Node cur = this.head;
        while (cur.next != this.head){
            cur = cur.next;
        }
        Node node = new Node(data);
        node.next = cur.next;
        cur.next = node;
    }

    //找到index-1的位置
    private Node searchIndex(int index){
         checkIndex(index);
        Node cur = this.head;
        for (int i = 0; i < index; i++) {
            cur = cur.next;
        }
        return cur;
    }

    private void checkIndex(int index){
        if (index < 0 || index > getLength()){
            throw new UnsupportedOperationException("index不合法");
        }

    }

    @Override
    public boolean addindex(int index, int data) {
        Node pre =  searchIndex(index);
        Node node = new Node(data);
        node.next = pre.next;
        pre.next = node;
        return true;
    }

    @Override
    public boolean contains(int key) {
        Node cur = this.head;
        Node node = new Node(key);
        if (head.data == key){
            cur = cur.next;
        }
        return false;
    }

    private Node SearchPre(int key){
        Node pre = this.head;
        while (pre.next != this.head){
            if(pre.next.data == key){
                return pre;
            }
            pre = pre.next;
        }
        return null;
    }

    @Override
    public int remove(int key) {
        Node pre = SearchPre(key);
        if (pre == null){
            throw new UnsupportedOperationException("key不存在");
        }
        Node del = pre.next;
        int oldData = pre.data;
        pre.next = del.next;
        return oldData;
    }

    @Override
    public void removeAllKey(int key) {
        Node pre = this.head;
        Node cur = this.head.next;
        while (cur != this.head){
            if(cur.data == key){
                pre.next = cur.next;
                cur = pre.next;
            }
            pre = cur;
            cur =cur.next;
        }
    }

    @Override
    public int getLength() {
        int length = 0;
        Node cur = this.head.next;
        while (cur != this.head) {
            length++;
            cur = cur.next;
        }
        return length;
    }

    @Override
    public void display() {
        Node cur = this.head.next;
        while (cur != head){
            System.out.print(cur.data+" ");
            cur = cur.next;
        }
        System.out.println();
    }

    @Override
    public void clear() {
        while (head.next != head){
            Node cur = this.head.next;
            head.next = cur.next;
            cur = cur.next;
        }
    }
}

测试用例：

public class TestMain {
    public static void main(String[] args) {
        HeadSingleLinkedListImpl headSingleList = new HeadSingleLinkedListImpl();
        headSingleList.addFirst(10);
        headSingleList.addFirst(20);
        headSingleList.display();
        headSingleList.addLast(40);
        headSingleList.addLast(10);
        headSingleList.addLast(50);
        headSingleList.display();
        headSingleList.addindex(2,100);
        headSingleList.addindex(3,200);
        headSingleList.display();
        headSingleList.remove(200);
        headSingleList.display();
        headSingleList.removeAllKey(10);
        headSingleList.display();
        System.out.println(headSingleList.getLength());
        headSingleList.clear();
        headSingleList.display();
    }
}