双向环形链表

节点代码:

/////////////////双链表节点///////////////////
public class Link {
    private int data;
    private Link next;
    private Link first;

    public Link(int data) {
        this.data = data;
    }

    public int getData() {
        return data;
    }

    public void setData(int data) {
        this.data = data;
    }

    public Link getNext() {
        return next;
    }

    public void setNext(Link next) {
        this.next = next;
    }

    public Link getFirst() {
        return first;
    }

    public void setFirst(Link first) {
        this.first = first;
    }

    @Override
    public String toString() {
        if (next==null){
            return "Link{" +
                    "data=" + data +
                    ", first=" + first.getData() +
                    ", next=null" +
                    '}';
        }else if (first==null){
            return "Link{" +
                    "data=" + data +
                    ", next=" + next.getData() +
                    ", first=null" +
                    '}';
        }
        return "Link{" +
                "data=" + data +
                ", next=" + next.getData() +
                ", first=" + first.getData() +
                '}';
    }
}

链表代码:

////////////////双向链表///////////////
public class DouLink {
    private Link head;
    private int size;

    //初始化头节点
    public DouLink(){
        head=new Link(0);
        size=0;
    }

    //查询全部
    public void getall(){
        Link temp = head;
        int con=0;
        while (con<size){
            temp=temp.getNext();
            System.out.println(temp);
            con++;
        }
    }

    //尾部添加
    public void add(Link link){
        Link temp = head;
        int con=0;
        while (con<size){
            temp=temp.getNext();
            con++;
        }
        temp.setNext(link);
        link.setFirst(temp);
        link.setNext(head.getNext());
        head.getNext().setFirst(link);
        size++;
    }

    //插入节点
    public void insert(int index,Link link){
        Link temp =head;
        int con=1;
        while (con<size){
            if (con==index){
                temp.getNext().setFirst(link);
                link.setNext(temp.getNext());
                temp.setNext(link);
                link.setFirst(temp);
                size++;
            }
            temp=temp.getNext();
            con++;
        }
    }

    //删除节点
    public void del(int index){
        Link temp =head;
        int con=1;
        while (con<size){
            if (con==index){
                temp.getNext().setFirst(temp);
                temp.setNext(temp.getNext().getNext());
                size--;
            }
            temp=temp.getNext();
            con++;
        }
    }
}

测试代码(貌似没必要发出来):

////////////双向链表测试////////////////
public class Test {
    public static void main(String[] args) {
        //初始化
        DouLink link = new DouLink();
        //添加
        link.add(new Link(11));
        link.add(new Link(12));
        link.add(new Link(13));
        link.getall();
        System.out.println();

        //插入
        link.insert(2,new Link(5));
        link.getall();
        System.out.println();

        //删除
        link.del(2);
        link.getall();
        System.out.println();
    }
}