双向链表

 

 

 

 

修改的时候思路和原来的单向链表思路一样

 

 

public class DoubleLinkedListDemo {
    //初始化头节点,里面的pre还有next不动
    HeroNode2 head = new HeroNode2(0,"","");

    public HeroNode2 getHeroNode2(){
        return head;
    }

    public void add(HeroNode2 head){
        HeroNode2 temp = head;
        while (true) {
            if (temp.next == null) {
                break;
            }temp=temp.next;
        }
        temp.next = head;  //temp.next = newHeadNode
        head.pre=temp;     //newHeadNode.pre = temp;
    }

    public void list(){
        if (head.next == null) {
            System.out.println("链表为空");
            return;
        }
        HeroNode2 temp = head.next;
        while (true) {
            if (temp == null) {
                break;
            }
            System.out.println(temp);
            temp=temp.next;
        }
    }
    public void update(HeroNode2 heroNode2){
        if (heroNode2.next == null) {
            System.out.println("链表为空");
            return;
        }
        HeroNode2 temp = heroNode2.next;
        boolean flag =false;
        while (true) {
            if (temp.next == null) {
                flag=true;
                break;
            }
            if (temp.no == heroNode2.no) {
                flag=true;
                break;
            }
            temp=temp.next;
        }
        if (flag) {
            temp.name = heroNode2.name;
            temp.nickName =heroNode2.nickName;
        }else {
            System.out.println("没有找到这个节点的编号"+heroNode2.no);
        }
    }

    /**
     * 双向链表中删除一个节点
     * 双向链表可以直接找到删除的这个节点
     * @param no
     */
    public void del(int no){
        if (head.next == null) {
            System.out.println("空链表");
            return;
        }
        HeroNode2 temp = head.next;//单链表是待删除的前一个,双链表直接从第一个节点开始
        boolean flag=false;
        while (true) {
            if (temp == null) {
                break;
            }
            if (temp.no == no) {
                flag=true;
                break;
            }
            temp=temp.next;
        }
        if (flag) {
            temp.pre.next=temp.next;
            //代码有问题 如果是最后一个节点就不需要执行下面这句话 否则空指针
            if (temp.next != null) {
                temp.next.pre=temp.pre;
            }
        }else {
            System.out.println("要删除的不存在");
        }
    }

}
class HeroNode2{
    //属性和节点信息,每个heronode就算一个节点
    public int no;
    public String name;
    public String nickName;
    public int val;
    public HeroNode2 next;
    public HeroNode2 pre;

    public HeroNode2(final int no, final String name, final String nickName) {
        this.no = no;
        this.name = name;
        this.nickName = nickName;
    }

    @Override
    public String toString() {
        return "HeroNode2{" +
                "no=" + no +
                ", name='" + name + '\'' +
                ", nickName='" + nickName + '\'' +
                ", val=" + val +
                ", next=" + next +
                ", pre=" + pre +
                '}';
    }
}

-----------------------------------------------------------------------------
修改后

public class DoubleLinkedListDemo {

    public static void main(String[] args) {
        DoubleLinkedList doubleLinkedList = new DoubleLinkedList();
        HeroNode2 heroNode1 = new HeroNode2(1, "松江", "及时雨");
        HeroNode2 heroNode2 = new HeroNode2(2, "卢俊义", "玉麒麟");
        HeroNode2 heroNode3 = new HeroNode2(3, "吴用", "智多星");
        HeroNode2 heroNode4 = new HeroNode2(4, "林冲", "豹子头");
        doubleLinkedList.add(heroNode1);
        doubleLinkedList.add(heroNode2);
        doubleLinkedList.add(heroNode3);
        doubleLinkedList.add(heroNode4);

        doubleLinkedList.list();

        System.out.println("---------------------------------");
        HeroNode2 newheroNode4 = new HeroNode2(4, "公孙胜", "入云龙");
        doubleLinkedList.update(newheroNode4);
        doubleLinkedList.list();

        doubleLinkedList.del(3);
        doubleLinkedList.list();



    }
}

    class DoubleLinkedList {
        //初始化头节点,里面的pre还有next不动
       private HeroNode2 head = new HeroNode2(0, "", "");

        public HeroNode2 getHead() {
            return head;
        }

        public void add(HeroNode2 heroNode2) {
            HeroNode2 temp = head;
            while (true) {
                if (temp.next == null) {
                    break;
                }
                temp = temp.next;
            }
            temp.next = heroNode2;  //temp.next = newHeadNode
            heroNode2.pre = temp;     //newHeadNode.pre = temp;
        }

        public void list() {
            if (head.next == null) {
                System.out.println("链表为空");
                return;
            }
            HeroNode2 temp = head.next;
            while (true) {
                if (temp == null) {
                    break;
                }
                System.out.println(temp);
                temp = temp.next;
            }
        }

        public void update(HeroNode2 heroNode2) {
            if (head.next == null) {
                System.out.println("链表为空");
                return;
            }
            HeroNode2 temp = head.next;
            boolean flag = false;
            while (true) {
                if (temp == null) {
                    break;
                }
                if (temp.no == heroNode2.no) {
                    flag = true;
                    break;
                }
                temp = temp.next;
            }
            if (flag) {
                temp.name = heroNode2.name;
                temp.nickName = heroNode2.nickName;
            } else {
                System.out.println("没有找到这个节点的编号" + heroNode2.no);
            }
        }

        /**
         * 双向链表中删除一个节点
         * 双向链表可以直接找到删除的这个节点
         *
         * @param no
         */
        public void del(int no) {
            if (head.next == null) {
                System.out.println("空链表");
                return;
            }
            HeroNode2 temp = head.next;//单链表是待删除的前一个,双链表直接从第一个节点开始
            boolean flag = false;
            while (true) {
                if (temp == null) {
                    break;
                }
                if (temp.no == no) {
                    flag = true;
                    break;
                }
                temp = temp.next;
            }
            if (flag) {
                temp.pre.next = temp.next;
                //代码有问题 如果是最后一个节点就不需要执行下面这句话 否则空指针
                if (temp.next != null) {
                    temp.next.pre = temp.pre;
                }
            } else {
                System.out.println("要删除的不存在");
            }
        }
    }

class HeroNode2{
    //属性和节点信息,每个heronode就算一个节点
    public int no;
    public String name;
    public String nickName;
    public HeroNode2 next;
    public HeroNode2 pre;

    public HeroNode2( int no,  String name, String nickName) {
        this.no = no;
        this.name = name;
        this.nickName = nickName;
    }

//    public HeroNode2(final int no, final String name, final String nickName, final HeroNode2 next, final HeroNode2 pre) {
//        this.no = no;
//        this.name = name;
//        this.nickName = nickName;
//        this.next = next;
//        this.pre = pre;
//    }


    @Override
    public String toString() {
        return "HeroNode2{" +
                "no=" + no +
                ", name='" + name + '\'' +
                ", nickName='" + nickName + '\'' +
                '}';
    }
}