Java数据结构-实现单链表

1.概览

2.代码

1.IList.java

public interface IList {
    //头插法
    public void addFirst(int data);
    //尾插法
    public void addLast(int data);
    //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);
    //查找是否包含关键字key是否在单链表当中
    public boolean contains(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);
    //得到单链表的长度
    public int size();
    public void display();
}

2.MySingleLinkedList.java

import java.util.List;

public class MySingleLinkedList implements IList{
    static class ListNode { //创建内部类
       public int val;
       public ListNode next;

       public ListNode(int val) {
           this.val = val;
       }
    }
    public ListNode head;

    public void addFirst(int data) {
        ListNode node = new ListNode(data);
        node.next = head;
        head = node;
    }

    public void addLast(int data) {
        ListNode node = new ListNode(data);
        if (head == null) {
            head = node;
            return;
        }
        ListNode cur = head;
        while (cur.next != null) {
            cur = cur.next;
        }
        cur.next = node;
    }
    public void addIndex(int index,int data) {
        int len = size();
        if(index < 0 || index > len) {
            System.out.println("下标不在正确范围内");
            return;
        }
        if (index == 0) {
            addFirst(data);
            return;
        }
        if (index == len) {
            addLast(data);
            return;
        }
        ListNode cur = head;
        while (index - 1 != 0) {
            cur = cur.next;
            index--;
        }
        ListNode node = new ListNode(data);
        node.next = cur.next;
        cur.next = node;
    }
    public ListNode findNodeOfKey(int key) {
        ListNode cur = head;
        while (cur.next != null) {
            if (cur.next.val == key) {
                return cur; //返回值为所查找值的前一个节点
            }
            cur = cur.next;
        }
        return null;
    }

    public void remove(int key) {
        if (head == null) {
            return;
        }
        if (head.val == key) {
            head = head.next;
            return;
        }
        ListNode cur = findNodeOfKey(key);
        if (cur == null) {
            return;
        }
        ListNode del = cur.next;
        cur.next = del.next;
    }

    public void removeAllKey(int key) {
        if (head == null) {
            return;
        }
        ListNode pre = head;
        ListNode cur = head.next;
        while (cur != null) {
            if (cur.val == key) {
                pre.next = cur.next;
                cur = cur.next;
            }else {
                pre = cur;
                cur = cur.next;
            }
        }
        //如果从头节点开始，连续两个数都为key的话，放在开头会删不掉
        if (head.val == key) {
            remove(key);
        }
    }
    public int size() {
        int len = 0;
        ListNode cur = head;
        while (cur != null) {
            len++;
            cur = cur.next;
        }
        return len;
    }

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

    public void display() {
        ListNode cur = head;
        while (cur != null) { //当cur指向最后一个节点，cur = null
            System.out.print(cur.val + " ");
            cur = cur.next;
        }
        System.out.println();
    }
}

3.Test.java

public class Test {
    public static void main(String[] args) {
        // 创建链表
        IList list = new MySingleLinkedList();
        //尾插法
        list.addLast(23);
        list.addLast(34);
        list.addLast(45);
        list.addLast(56);
        //头插法
        list.addFirst(12);
        //打印链表
        list.display();
        System.out.println("----------");
        //输出元素个数
        int size = list.size();
        System.out.println("size = " + size);
        System.out.println("----------");
        //任意位置插入
        list.addIndex(0,0);
        list.addIndex(2,666);
        list.addIndex(7,78);
        list.display();
        System.out.println("----------");
        //删除第一次出现关键字为key的节点
        list.remove(666);
        list.display();
        System.out.println("----------");
        //删除所有值为key的节点
        list.addIndex(3,999);
        list.addFirst(999);
        list.display();
        list.removeAllKey(999);
        list.display();
    }
}

3.运行结果