链表（LinkedList）

杂亿稿2025-08-30 14:35

链表

链表：⼀种物理存储结构上⾮连续存储结构，数据元素的逻辑顺序是通过链表中的引⽤链接次序实现的

链表结构

LinkedList单向链表

LinkedList的创建与打印
复制代码 
public class MyLinkedList {
    static class ListNode{
       public int val;
       public ListNode next;
       public ListNode(int val){
           this.val=val;
       }
    }
    public ListNode head;
    public void creatList(){
        ListNode node1=new ListNode(11);
        ListNode node2=new ListNode(22);
        ListNode node3=new ListNode(33);
        ListNode node4=new ListNode(44);
        ListNode node5=new ListNode(55);
        node1.next=node2;
        node2.next=node3;
        node3.next=node4;
        node4.next=node5;
        this.head=node1;
    }
    public void print(){
        ListNode cur=head;
        while(cur!=null){
            System.out.print(cur.val+" ");
            cur=cur.next;
        }
        System.out.println();
    }
}
复制代码 
public class Test {
    public static void main(String[] args) {
        MyLinkedList myLinkedList=new MyLinkedList();
        myLinkedList.creatList();
        myLinkedList.print();
    }
}
复制代码
LinkedList的头插法
复制代码 
public void addFirst(int data) {
    ListNode node=new ListNode(data);
    node.next=head;
    head=node;
}
复制代码 
public class Test {
    public static void main(String[] args) {
        MyLinkedList myLinkedList=new MyLinkedList();
        myLinkedList.addFirst(1);
        myLinkedList.addFirst(2);
        myLinkedList.addFirst(3);
        myLinkedList.print();
    }
}
LinkedList的尾插法
复制代码 
public void addLast(int data) {
    ListNode node=new ListNode(data);
    ListNode cur=head;
    if(cur==null){
        head=node;
        return;
    }
    while (cur.next!=null){
        cur=cur.next;
    }
    cur.next=node;
}
public class Test {
    public static void main(String[] args) {
        MyLinkedList myLinkedList=new MyLinkedList();
        myLinkedList.addLast(10);
        myLinkedList.addLast(20);
        myLinkedList.addLast(30);
        myLinkedList.print();
    }
}
LinkedList的指定位置插入法

public void addIndex(int index, int data) {

if(index<0||index>size()){

return ;

}

if (index==0){

addFirst(data);

return;

}

if(index==size()){

addLast(data);

return;

}

ListNode node=new ListNode(data);

ListNode cur=searchIndex(index);

if(cur==null){

return;

}

node.next=cur.next;

cur.next=node;

}

public ListNode searchIndex(int index){

if(index<0||index>size()){

return null;

}

ListNode cur=head;

int count=0;

while (count!=index-1){

cur=cur.next;

count++;

}

return cur;

}

复制代码 
public class Test {
    public static void main(String[] args) {
        MyLinkedList myLinkedList=new MyLinkedList();
        myLinkedList.creatList();
        myLinkedList.print();
        myLinkedList.addIndex(0,0);
        myLinkedList.addIndex(6,66);
        myLinkedList.print();
    }
}
Linked List的contains方法
复制代码 
public boolean contains(int key) {
    ListNode cur=head;
    while(cur!=null){
        if(cur.val==key){
            return true;
        }
        cur=cur.next;
    }
    return false;
}
复制代码 
public class Test {
    public static void main(String[] args) {
        MyLinkedList myLinkedList=new MyLinkedList();
        myLinkedList.creatList();
        System.out.println(myLinkedList.contains(33));
        System.out.println(myLinkedList.contains(66));

    }
}
LinkedList的删除第一次出现的key关键字
复制代码 
public ListNode searchIndex(int index){
  if(index<0||index>size()){
      return null;
  }
  ListNode cur=head;
  int count=0;
  while (count!=index-1){
      cur=cur.next;
      count++;
  }
  return cur;
}

// 查找是否包含关键字 key 是否在单链表当中
public boolean contains(int key) {
    ListNode cur=head;
    while(cur!=null){
        if(cur.val==key){
            return true;
        }
        cur=cur.next;
    }
    return false;
}
复制代码 
public class Test {
    public static void main(String[] args) {
        MyLinkedList myLinkedList=new MyLinkedList();
        myLinkedList.addLast(10);
        myLinkedList.addLast(20);
        myLinkedList.addLast(30);
        myLinkedList.addLast(40);
        myLinkedList.print();
        myLinkedList.remove(30);
        myLinkedList.print();
    }
}
LinkedList的删除所有key关键字
复制代码 
public void removeAllKey(int key) {
    if (head==null){
        return;
    }
    ListNode prev=head;
    ListNode cur=head.next;
    while (cur!=null){
        if (cur.val==key){
            prev.next=cur.next;
            cur=cur.next;
        }else {
            prev=cur;
            cur=cur.next;
        }
    }
    if (head.val==key){
        head=head.next;
    }
}
复制代码 
public class Test {
    public static void main(String[] args) {
        MyLinkedList myLinkedList=new MyLinkedList();
        myLinkedList.addLast(10);
        myLinkedList.addLast(30);
        myLinkedList.addLast(20);
        myLinkedList.addLast(30);
        myLinkedList.addLast(40);
        myLinkedList.addLast(30);
        myLinkedList.print();
        myLinkedList.removeAllKey(30);
        myLinkedList.print();

    }
}
LinkedList的size()方法

public int size() {

ListNode cur=head;

int count=0;

while (cur!=null){

count++;

cur=cur.next;

}

return count;

}

复制代码 
public class Test {
    public static void main(String[] args) {
        MyLinkedList myLinkedList=new MyLinkedList();
        myLinkedList.creatList();
        System.out.println(myLinkedList.size());
    }
}
LinkedList的clear方法
复制代码 
public void clear() {
    head=null;
}
复制代码 
public class Test {
    public static void main(String[] args) {
        MyLinkedList myLinkedList=new MyLinkedList();
        myLinkedList.creatList();
        myLinkedList.print();
        myLinkedList.clear();
        System.out.println("clear之后：");
        myLinkedList.print();
    }
}
LinkedList的完整实现
复制代码 
public class MyLinkedList {
    static class ListNode{
       public int val;
       public ListNode next;
       public ListNode(int val){
           this.val=val;
       }
    }
    public ListNode head;
    public ListNode last;
    public void creatList(){
        ListNode node1=new ListNode(11);
        ListNode node2=new ListNode(22);
        ListNode node3=new ListNode(33);
        ListNode node4=new ListNode(44);
        ListNode node5=new ListNode(55);
        node1.next=node2;
        node2.next=node3;
        node3.next=node4;
        node4.next=node5;
        this.head=node1;
    }
    public void print(){
        ListNode cur=head;
        while(cur!=null){
            System.out.print(cur.val+" ");
            cur=cur.next;
        }
        System.out.println();
    }
    // 头插法
    public void addFirst(int data) {
        ListNode node=new ListNode(data);
        node.next=head;
        head=node;
    }

    // 尾插法
    public void addLast(int data) {
        ListNode node=new ListNode(data);
        ListNode cur=head;
        if(cur==null){
            head=node;
            return;
        }
        while (cur.next!=null){
            cur=cur.next;
        }
        cur.next=node;
    }

    // 任意位置插入，第一个数据节点为 0 号下标
    public void addIndex(int index, int data) {
        if(index<0||index>size()){
            return ;
        }
        if (index==0){
            addFirst(data);
            return;
        }
        if(index==size()){
            addLast(data);
            return;
        }
        ListNode node=new ListNode(data);
        ListNode cur=searchIndex(index);
        if(cur==null){
            return;
        }
        node.next=cur.next;
        cur.next=node;

    }
    public ListNode searchIndex(int index){
      if(index<0||index>size()){
          return null;
      }
      ListNode cur=head;
      int count=0;
      while (count!=index-1){
          cur=cur.next;
          count++;
      }
      return cur;
    }

    // 查找是否包含关键字 key 是否在单链表当中
    public boolean contains(int key) {
        ListNode cur=head;
        while(cur!=null){
            if(cur.val==key){
                return true;
            }
            cur=cur.next;
        }
        return false;
    }

    // 删除第一次出现关键字为 key 的节点
    public void remove(int key) {
        if (head==null){
            return;
        }
        if (head.val==key){
            head=head.next;
            return;
        }
        ListNode pre=findKey(key);
        if (pre==null){
            return;
        }
        ListNode delete=pre.next;
        pre.next=delete.next;
    }
    public ListNode findKey(int key){
        ListNode prev=head;
        while (prev.next!=null){
            if(prev.next.val==key){
                return prev;
            }
            prev = prev.next;
        }
        return null;
    }
    // 删除所有值为 key 的节点
    public void removeAllKey(int key) {
        if (head==null){
            return;
        }
        ListNode prev=head;
        ListNode cur=head.next;
        while (cur!=null){
            if (cur.val==key){
                prev.next=cur.next;
                cur=cur.next;
            }else {
                prev=cur;
                cur=cur.next;
            }
        }
        if (head.val==key){
            head=head.next;
        }
    }

    // 得到单链表的长度
    public int size() {
        ListNode cur=head;
        int count=0;
        while (cur!=null){
            count++;
            cur=cur.next;
        }
        return count;
    }

    public void clear() {
        head=null;
    }
    
}

DoubleLinked List双向链表

Double Linked List的头插法
复制代码 
public void addFirst(int data) {
    LinkedNode node=new LinkedNode(data);
    if(head==null){
        head=node;
        last=node;
    }else {
        node.next=head;
        head.prev=node;
        head=node;
    }
}
DoubleLinkedList的尾插法
复制代码 
public void addLast(int data) {
    LinkedNode node=new LinkedNode(data);
    if (head==null){
        head=node;
        last=node;
    }else {
        last.next=node;
        node.prev=last;
        last=node;
    }
}
DoubleLinkedList的任意位置插入的方法
复制代码 
public void addIndex(int index, int data) {
    if (index<0||index>size()){
        System.out.println("下标位置不合法："+index);
        return;
    }
    if (index==0){
        addFirst(data);
        return;
    }
    if(index==size()){
        addLast(data);
        return;
    }
    LinkedNode node=new LinkedNode(data);
    LinkedNode cur=search(index);
    node.next=cur;
    cur.prev.next=node;
    node.prev=cur.prev;
    cur.prev=node;
}
public LinkedNode search(int index){
    LinkedNode cur=head;
    while (index!=0){
        cur=cur.next;
        index--;
    }
    return cur;
}
DoubleLinkedList删除key节点的方法
复制代码 
// 删除第一次出现关键字为 key 的节点
public void remove(int key) {
    LinkedNode cur=head;
    while (cur!=null){
        if(cur.val == key) {
            if(cur == head) {
                //删除头节点
                head = head.next;
                if(head == null) {
                    //只有一个节点的情况下
                    last = null;
                }else {
                    head.prev = null;
                }
            }else {
                //删除中间和尾巴
                if(cur.next == null) {
                    //尾巴
                    cur.prev.next = cur.next;
                    last = last.prev;
                }else {
                    cur.prev.next = cur.next;
                    cur.next.prev = cur.prev;
                }
            }
            return;
        }
        cur = cur.next;
    }
}

// 删除所有值为 key 的节点
public void removeAllKey(int key) {
    LinkedNode cur = head;
    while (cur != null) {
        if(cur.val == key) {
            if(cur == head) {
                //删除头节点
                head = head.next;
                if(head == null) {
                    //只有一个节点的情况下
                    last = null;
                }else {
                    head.prev = null;
                }
            }else {
                //删除中间和尾巴
                if(cur.next == null) {
                    //尾巴
                    cur.prev.next = cur.next;
                    last = last.prev;
                }else {
                    cur.prev.next = cur.next;
                    cur.next.prev = cur.prev;
                }
            }
        }
        cur = cur.next;
    }
}
DoubleLinkedList的contains（）方法

public boolean contains(int key) {
LinkedNode cur=head;
while (cur!=null){
if (cur.val==key){
return true;
}
cur=cur.next;
}
return false;
}

Double Linked List的size（）方法
复制代码 
public int size() {
    LinkedNode cur=head;
    int count=0;
    while (cur!=null){
        count++;
        cur=cur.next;
    }
    return count;
}
Double Linked List的display()方法
复制代码 
public void display() {
    LinkedNode cur=head;
    while (cur!=null){
        System.out.print(cur.val+" ");
        cur=cur.next;
    }
    System.out.println();
}
DoubleLinkedList的clear()方法
复制代码 
public void clear() {
    LinkedNode cur = head;
    while (cur != null) {
        LinkedNode curN = cur.next;

        cur.prev = null;
        cur.next = null;
        cur = curN;
    }
    head = null;
    last = null;
}

DoubleLinkedList的完整实现

复制代码 
public class DoubleLinkedList {
    static class LinkedNode{
        public int val;
        public LinkedNode next;
        public LinkedNode prev;
        public LinkedNode(int val){
            this.val=val;
        }
    }
    public LinkedNode head;
    public LinkedNode last;

    public void addFirst(int data) {
        LinkedNode node=new LinkedNode(data);
        if(head==null){
            head=node;
            last=node;
        }else {
            node.next=head;
            head.prev=node;
            head=node;
        }
    }

    // 尾插法
    public void addLast(int data) {
        LinkedNode node=new LinkedNode(data);
        if (head==null){
            head=node;
            last=node;
        }else {
            last.next=node;
            node.prev=last;
            last=node;
        }
    }

    // 任意位置插入，第一个数据节点为 0 号下标
    public void addIndex(int index, int data) {
        if (index<0||index>size()){
            System.out.println("下标位置不合法："+index);
            return;
        }
        if (index==0){
            addFirst(data);
            return;
        }
        if(index==size()){
            addLast(data);
            return;
        }
        LinkedNode node=new LinkedNode(data);
        LinkedNode cur=search(index);
        node.next=cur;
        cur.prev.next=node;
        node.prev=cur.prev;
        cur.prev=node;
    }
    public LinkedNode search(int index){
        LinkedNode cur=head;
        while (index!=0){
            cur=cur.next;
            index--;
        }
        return cur;
    }

    // 查找是否包含关键字 key 是否在单链表当中
    public boolean contains(int key) {
        LinkedNode cur=head;
        while (cur!=null){
           if (cur.val==key){
               return true;
           }
            cur=cur.next;
        }
        return false;
    }

    // 删除第一次出现关键字为 key 的节点
    public void remove(int key) {
        LinkedNode cur=head;
        while (cur!=null){
            if(cur.val == key) {
                if(cur == head) {
                    //删除头节点
                    head = head.next;
                    if(head == null) {
                        //只有一个节点的情况下
                        last = null;
                    }else {
                        head.prev = null;
                    }
                }else {
                    //删除中间和尾巴
                    if(cur.next == null) {
                        //尾巴
                        cur.prev.next = cur.next;
                        last = last.prev;
                    }else {
                        cur.prev.next = cur.next;
                        cur.next.prev = cur.prev;
                    }
                }
                return;
            }
            cur = cur.next;
        }
    }

    // 删除所有值为 key 的节点
    public void removeAllKey(int key) {
        LinkedNode cur = head;
        while (cur != null) {
            if(cur.val == key) {
                if(cur == head) {
                    //删除头节点
                    head = head.next;
                    if(head == null) {
                        //只有一个节点的情况下
                        last = null;
                    }else {
                        head.prev = null;
                    }
                }else {
                    //删除中间和尾巴
                    if(cur.next == null) {
                        //尾巴
                        cur.prev.next = cur.next;
                        last = last.prev;
                    }else {
                        cur.prev.next = cur.next;
                        cur.next.prev = cur.prev;
                    }
                }
            }
            cur = cur.next;
        }
    }
    // 得到单链表的长度
    public int size() {
        LinkedNode cur=head;
        int count=0;
        while (cur!=null){
            count++;
            cur=cur.next;
        }
        return count;
    }

    // 遍历显示链表元素（假设功能），实际可根据需求定义
    public void display() {
        LinkedNode cur=head;
        while (cur!=null){
            System.out.print(cur.val+" ");
            cur=cur.next;
        }
        System.out.println();
    }

    // 清空链表
    public void clear() {
        LinkedNode cur = head;
        while (cur != null) {
            LinkedNode curN = cur.next;
            //cur.val = null;
            cur.prev = null;
            cur.next = null;
            cur = curN;
        }
        head = null;
        last = null;
    }
}

Linked List的使用

【说明】

  1. LinkedList实现了List接⼝

  2. LinkedList的底层使⽤了双向链表

  3. LinkedList没有实现RandomAccess接⼝，因此LinkedList不⽀持随机访问

  4. LinkedList的任意位置插⼊和删除元素时效率⽐较⾼，时间复杂度为O(1)

  5. LinkedList⽐较适合任意位置插⼊的场景

LinkedList的常用方法
复制代码 
import java.util.LinkedList;

public class Test {
    public static void main(String[] args) {
        LinkedList<Integer> linkedList=new LinkedList<>();
        LinkedList<Integer> linkedList1=new LinkedList<>();
        linkedList1.add(55);
        linkedList1.add(66);
        //尾插
        linkedList.add(11);
        linkedList.add(22);
        linkedList.add(33);
        System.out.println(linkedList);
        //元素插入index位置
        linkedList.add(0,0);
        linkedList.add(4,44);
        System.out.println(linkedList);
        //插入其他链表的元素
        linkedList.addAll(linkedList1);
        System.out.println(linkedList);
        //删除元素
        linkedList.remove(0);
        linkedList.remove(4);
        System.out.println(linkedList);
        //获取下标元素
        System.out.println(linkedList.get(3));
        //设置index元素
        linkedList.set(1,111);
        System.out.println(linkedList);
        //判断元素是否存在
        System.out.println(linkedList.contains(44));
        System.out.println(linkedList.contains(22));
        //返回下标
        System.out.println(linkedList.indexOf(55));
        System.out.println(linkedList.lastIndexOf(111));
        //截取
        System.out.println(linkedList.subList(0, 4));
        //清空
        System.out.println(linkedList);
        linkedList.clear();
        System.out.println(linkedList);
    }
}
Linked List的遍历
复制代码 
import java.util.LinkedList;
import java.util.ListIterator;
public class Test {
    public static void main(String[] args) {
        LinkedList<Integer> linkedList=new LinkedList<>();
        linkedList.add(1);
        linkedList.add(2);
        linkedList.add(3);
        //直接遍历
        System.out.println(linkedList);
        //for循环遍历
        for (int i = 0; i <linkedList.size() ; i++) {
            System.out.print(linkedList.get(i)+" ");
        }
        System.out.println();
        //foreach遍历
        for (int i:linkedList) {
            System.out.print(i+" ");
        }
        System.out.println();
        //迭代器遍历
        ListIterator<Integer> iterator=linkedList.listIterator();
        while (iterator.hasNext()){
            System.out.print(iterator.next()+" ");
        }
        System.out.println();
        ListIterator<Integer> iterator1=linkedList.listIterator(linkedList.size());
        while (iterator1.hasPrevious()){
            System.out.print(iterator1.previous()+" ");
        }
        System.out.println();

    }
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