1. 概况

链表在逻辑上是连续的，在物理上不一定连续。

分类：

单向、双向
带头、不带头
循环、非循环

2. 思路

data：数值域，里面存储的数据
next：引用变量 -> 下一个节点的地址

尾巴节点：当这个节点的next域为null的时候

头节点：整个链表当中的第一个节点

单向不带头非循环链表：

单向带头非循环链表：

单向不带头循环链表：

3. 定义链表节点

class Node {
    public int val;
    public Node next;

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

4. 实现方法

//生成链表
public void createList()
//打印链表内容
public void display()
//打印链表长度
public int length()
//查找是否包含关键字key在链表当中
public boolean contains(int key)

//头插法
public void addFirst(int data)
//尾插法
public void addLast(int data)

//找到前一个地址
public Node searchPrev(int index)
//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)

//找关键字key的前驱
public Node searchPrevNode(int key)
//删除第一次出现关键字为key的节点
public void remove(int key)
//删除所有值为key的节点
public void removeAllKey(int key)

//清空链表
public void clear()

5. 源代码

MyLinkedList.java

class Node {
    public int data;
    public Node next;
    public Node(int data) {
        this.data = data;
    }
}
public class MyLinkedList {
    public Node head;//标识单链表的头节点

    public void createList() {
        Node node1 = new Node(1);
        Node node2 = new Node(2);
        Node node3 = new Node(3);
        Node node4 = new Node(4);
        Node node5 = new Node(5);

        node1.next = node2;
        node2.next = node3;
        node3.next = node4;
        node4.next = node5;

        this.head = node1;
    }
    //打印链表内容
    public void display() {
        Node cur = this.head;
        while(cur != null) {
            System.out.print(cur.data+" ");
            cur = cur.next;
        }
        System.out.println();
    }
    //打印链表长度
    public int length() {
        int count = 0;
        Node cur = this.head;
        while (cur != null) {
            cur = cur.next;
            count++;
        }
        return count;
    }
    //查找是否包含关键字key在链表当中
    public boolean contains(int key) {
        Node cur = this.head;
        while (cur != null) {
            if(cur.data == key) {
                return true;
            }
            cur = cur.next;
        }
        return false;
    }
    //头插法
    public void addFirst(int data) {
        Node node = new Node(data);
        if (this.head == null) {
            this.head = node;
        } else {
            node.next = this.head;
            this.head = node;
        }

    }
    //尾插法
    public void addLast(int data) {
        Node node = new Node(data);
        if (this.head == null) {
            this.head = node;
        } else {
            Node cur = this.head;
            while (cur.next != null) {
                cur = cur.next;
            }
            cur.next = node;
        }
    }
    //找到前一个地址
    public Node searchPrev(int index) {
        Node cur = this.head;
        int count = 0;
        while (count != index-1) {
            cur = cur.next;
            count++;
        }
        return cur;
    }

    //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 > length()) {
            throw new RuntimeException("插入位置错误");
        }
        //头插法
        if (index == 0) {
            addFirst(data);
            return;
        }
        //尾插法
        if (index == length()) {
            addLast(data);
            return;
        }
        Node cur = searchPrev(index);
        Node node = new Node(data);
        node.next = cur.next;
        cur.next = node;
    }

    //找关键字key的前驱
    public Node searchPrevNode(int key) {
        Node cur = this.head;
        while (cur.next != null) {
            if (cur.next.data == key) {
                return cur;
            }
            cur = cur.next;
        }
        return null;
    }
    //删除第一次出现的关键字key
    public void remove(int key) {
        if (this.head == null) return;
        //单独判断头节点的问题
        if (this.head.data == key) {
            this.head = this.head.next;
            return;
        }
        Node cur = searchPrevNode(key);
        if (cur == null) {
            System.out.println("没有你要删除的节点！");
            return;
        }
        Node del = cur.next;
        cur.next = del.next;
    }

    //删除所有值为key的节点
    public void removeAllKey(int key) {
        if (this.head == null) {
            return;
        }
        Node prev = this.head;
        Node cur = this.head.next;
        while (cur != null) {
            if(cur.data == key) {
                prev.next = cur.next;
                cur = cur.next;
            } else {
                prev = cur;
                cur = cur.next;
            }
        }

        //最后判断头节点
        if (this.head.data == key) {
            this.head = this.head.next;
        }
    }

    //清空链表
    public void clear() {
        while (this.head != null) {
            Node curNext = this.head.next;
            this.head.next = null;
            this.head = curNext;
        }
    }
}

test.java

测试代码

public class test {
    public static void main(String[] args) {
        MyLinkedList myLinkedList = new MyLinkedList();
        myLinkedList.createList();
        myLinkedList.display();//1 2 3 4 5
        System.out.println(myLinkedList.length());
        myLinkedList.remove(1);
        myLinkedList.display();//2 3 4 5
    }
}