双向链表的初始化与增删改查

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链表

双链表

结点类

先创建结点类

public class HeroNode2 {
    public int no;
    public String name;
    public String nikeName;
    public HeroNode2 next;
    public HeroNode2 pre;
    
    public HeroNode2(int no, String name, String nikeName){
        this.no = no;
        this.name = name;
        this.nikeName = nikeName;
    }
    
    @Override
    public String toString(){
        return "HeroNo:" + no + "HeroName" + name + "nikeName" + nikeName;
    } 
}

构建双链表类

里面构造方法

public class doubleLinked{
    private HeroNode2 head = new HeroNode2(0,"","");
    
    public HeroNode2 getHead() {
        return head;
    }
    
    //. . . . . . . 
   
}

测试类

public class DoubleLinkedList {
    public static void main(String[] args) {
        HeroNode2 hero1 = new HeroNode2(1,"Marisa","mar");
        HeroNode2 hero2 = new HeroNode2(2,"Reimu","rei");
        HeroNode2 hero3 = new HeroNode2(3,"Cirno","qii");
        HeroNode2 hero4 = new HeroNode2(4,"Meirin","hon");
        System.out.println("--------Inilization--------");
        DoubleLinked doubleLinked = new DoubleLinked();
        doubleLinked.add(hero1);
        doubleLinked.add(hero2);
        doubleLinked.add(hero3);
        doubleLinked.add(hero4);
        doubleLinked.add(new HeroNode2(5,"ABC","A"));

        doubleLinked.list();
        System.out.println(doubleLinked.listSingle(2));
        doubleLinked.ModifyPos(3,"新改的");
        doubleLinked.list();

        HeroNode2 hero7 = new HeroNode2(5,"Yukari","zima");
        doubleLinked.insert(1,hero7);
        System.out.println("----------Insert-----------");
        doubleLinked.list();

        System.out.println("-----------Del-------------");
        doubleLinked.del(5);
        doubleLinked.list();
    }
}

遍历

可以直接使用head

public void list() {
       
       if(head.next = null){
           System.out.println("The doublieLink is null");
           return;
       }
       HeroNode2 temp = head.next;
       while(true){
           if(temp == null){
               break;
           }
           System.out.print(temp);
           temp = temp.next;
       }
   }

查找特定值

public String findSingle(int pos){
        if(head.next == null){
            System.out.println("null");
            return;
        }
        HeroNode2 tem = head.next;
        //注意这里的head.next开始，移动到pos位置只需要pos-1次
        for(int i = 1; i < pos; i++){
            tem = tem.next;
        }
        return tem.name;
    }

修改结点

public void ModifyPos(int pos, String name){
    HeroNode2 tem = head.next;
    if(tem.next == null){
        System.out.println("The link is null");
        return;
    }
    while(tem.no != pos ){
        tem = tem.next;
    }
    
    /**for
    *循环也可以，上面不要忘记处理null的条件，其实个人觉得没什么必要
    for(int idnex = 1; index < pos; index++){
    	tem = tem.next;
    }
    */
    tem.name = name;
}

初始化

public void add(HeroNode2 heroNode){
    HeroNode2 temp = head.next;
    while(temp.next != null){
        temp = temp.next;
    }
    temp.next = heroNode;
    heroNode.pre = temp;
}

添加结点

public void insert(int pos, HeroNode2 newNode){
    HeroNode2 temp = head.next;
    for(int index = 1; index < pos; index++){
        temp = temp.next;
    }
    HeroNode2 last = temp.next;
    temp.next = newNode;
    newNode.next = last;
    last.pre = newNode;
    newNode.pre = temp;
}

删除结点

要考虑删除时不存在的情况，不能使用for循环和直接的指向

用前后指针来写，注意要加多一个最后为空的判断情况

public void delNode(int no){
    if(head.next == null){
        System.out.println("NULL");
        return;
    }
    HeroNode2 prer = head.next;
    flag = false;
    while(true){
        if(temp == ture){
            System.out.println("NULL");
            return;
        }
        else{
            if(temp.no == no){
                flag = true;
                break;
            }
            temp = temp.next;
        }
    }
    if(flag == true){
        temp.pre.next = temp.next;
        if(temp.next != null){
            temp.next.pre = temp;.pre;
        }
    }
    else {
        System.out.printf("del %d not exist\n",no);
    }
}