I have been working for a long time and I often use the framework. I feel that it has become a coding. It is recommended to flash the lettcode if you have time. It will be forgotten after a long time. After writing it for a long time, record it and write it after understanding. It is very easy to write it in reverse order. Blogs are written in various ways, but I feel that the explanation is still unclear, so I will summarize here:
1. First define the structure of the linked list
The defined structure Node<T> is a generic type that data can be customized, which increases flexibility:
public class Node<T> {
public T data;
public Node next; //可以理解为C语言的指针
public Node(){}
public Node(T data){
this.data = data;
}
public T getData() {
return data;
}
public void setData(T data) {
this.data = data;
}
public Node getNext() {
return next;
}
public void setNext(Node next) {
this.next = next;
}
}The head pointer data designed here is empty by default, which is null;
Execute temp =p ,p=q The execution process is as follows:
Execute tmp =p;p=q;q=q->next where q=q->next is C/C++-like writing for explanation;
It is easy to overlook here: p.next=null is easy to form a loop:
q=q->next, here I understand it as a probe, whether the query has reached the end of the linked list:
Additions and deletions, reverse order, the specific code is as follows:
import java.lang.reflect.Array;
import java.util.ArrayList;
/**
* @ClassName MyList
* @Description
* @Author qianxl
* @Date 2019-09-07 17:34
* @Version 1.0
**/
public class MyList<T> {
public Node head = new Node(-1);
public Node current;
/**
* @param data
* @description: 添加元素
* @return: {@link Node}
* @author qianxl
* @date: 2019/9/7
* @since 1.0
*/
public Node add(T data) {
Node temp = head;
Node before = new Node();
do {
before = temp;
} while ((temp = temp.next) != null);
//注释部分是代码重构使用do while
// before = temp;
// while (temp != null) {
// before = temp;
// temp = temp.next;
// }
temp = new Node(data);
before.next = temp;
return head;
}
public Node remove(T values) {
Node data = this.head;
boolean flag = false;
Node before;
Node temp = data.next;
do {
before = data;
if (values.equals(temp.data)) {
flag = true;
break;
}
} while ((temp = temp.next) != null);
//注释部分是代码重构使用do while
// Node temp = data.next;
// Node before =data;
// while (temp != null) {
// if (values.equals(temp.data)) {
// flag = true;
// break;
// }
// before = temp;
// temp = temp.next;
// }
if (flag) {
before.next = temp.next;
}
return head;
}
/**
* @param
* @description: 计算集合的长度
* @return: {@link int}
* @author qianxl
* @date: 2019/9/7
* @since 1.0
*/
public int size() {
Node data = head;
int count = 0;
Node tmp;
while (data != null) {
data = data.next;
count++;
}
return count - 1;//head 不存入数据
}
/**
* @param index
* @param value
* @description: 指定位置插入值
* @return: {@link Node}
* @author qianxl
* @date: 2019/9/8
* @since 1.0
*/
public Node insert(int index, T value) {
Node data = head.next; //去掉头指针
if (index > this.size() || index < 1) {
return head;
}
if (index == 1) {
Node node = new Node(value);
node.next = head.next; //将新建的节点的指针指向，之前head 头结点指向的指针
head.next = node;
return head;
}
int count = 1;
Node before = data; //
do {
if (index == count) {
Node node = new Node(value);
node.next = data;
before.next = node; //指向新建的节点
break;
}
count++;
before = data;
data = data.next;
} while (data != null);
//注释部分是代码重构使用do while
// Node before =data;
// while (data != null) {
// if (index == count) {
// Node node = new Node(value);
// node.next=data;
// before.next=node; //指向新建的节点
// break;
// }
// count++;
// before = data;
// data = data.next;
// }
return head;
}
/**
* @param
* @description: 链表逆序
* @return: {@link Node}
* @author qianxl
* @date: 2019/9/8
* @since 1.0
*/
public Node reverse() {
Node p,q=null;
p = head.next; //指针 引用
q = head.next.next;//q 指针可以理解为探针，在探是否到达链表末尾了
Node tmp=null;
p.setNext(null); //防止回环
while (q != null) {
tmp =p;
p=q;
q=q.next; //q=q->next 起到探针的作用
p.next=tmp;
}
head.next =p;
return head;
}
public void print(Node node) {
if (node.next == null) {
return;
}
Node temp = node.next;
while (temp != null) {
System.out.print(temp.data+" ");
temp = temp.next;
}
System.out.println();
}
/**
* @param array
* @description: 将数组转换为list head.next 理解为C语言指针，写链表操作一定要画图！
* @return: {@link Node}
* @author qianxl
* @date: 2019/9/7
* @since 1.0
*/
public Node arrayToList(T[] array) {
Node data = head;
for (int i = 0; i < array.length; i++) {
Node node = new Node(array[i]);
data.next = node; //表情指向前驱
data = node; //表示
}
return head;
}
public static void main(String arg[]) {
MyList<Object> list = new MyList<>();
Node ddd = list.add("ddd");
list.add("this is a list");
list.add("fffff");
list.remove("ddd");
list.print(ddd);
Node node = list.arrayToList(new String[]{"2","3","4"});
list.print(node);
// list.insert(1, "8");
list.add("8");
list.print(node);
System.out.println();
list.reverse();
list.print(node);
}
}to sum up