一起来学习单向链表吧(●‘◡‘●)-优快云博客

本文链接：https://blog.youkuaiyun.com/qq_47640605/article/details/125715949

学习单向链表和^o^

List的接口

import java.util.Comparator;
public interface List<E> extends Iterable<E> {
    public void add(E element);

    public void add(int index, E element);

    public void remove(E element);

    public E remove(int index);

    public E get(int index);

    public E set(int index, E element);

    public int size();

    public int indexOf(E element);

    public boolean isEmpty();

    public boolean contains(E element);

    public void clear();

    public void sort(Comparator<E> c);

    public List<E> subList(int fromIndex, int toIndex);
}

单向链表的实现

package 动态链表;

import 接口.List;

import java.util.Comparator;
import java.util.Iterator;

//单向链表
public class LinkedSinglyList<E> implements List<E> {
    //定义一个节点，内部类
    private class Node {
        E data;//数据域 用来存储数据
        Node next;//指针域 用来存储下一个节点对象的地址

        public Node() {
            this(null, null);
        }

        public Node(E data) {
            this(data, null);
        }

        public Node(E data, Node next) {
            this.data = data;
            this.next = next;
        }

        @Override
        public String toString() {
            return data.toString();
        }
    }

    private Node head;//是链表当中的头指针，指向第一个结点对象
    private Node tail;//是链表当中的尾指针 指向最后一个结点对象
    private int size;//是链表当中的有效元素个数

    public LinkedSinglyList() {
        head = null;
        tail = null;
        size = 0;
    }

    public LinkedSinglyList(E[] arr) {
        for (E e : arr) {
            add(e);
        }
    }

    /**
     * 默认在链表尾部添加元素
     *
     * @param element
     */
    @Override
    public void add(E element) {
        add(size, element);
    }

    /**
     * 在链表指定角标index添加一个元素
     *
     * @param index
     * @param element
     */
    @Override
    public void add(int index, E element) {
        if (index < 0 || index > size) {
            throw new ArrayIndexOutOfBoundsException("add index out of bounds");
        }
        //创建一个新的结点对象
        Node node = new Node(element);
        if (isEmpty()) {
            //链表为空
            head = node;
            tail = node;
            //size++;
        } else if (index == 0) {
            //在表头添加
            node.next = head;
            head = node;
            //size++;
        } else if (index == size) {
            //在表尾添加
            tail.next = node;
            tail = node;
            //size++;
        } else {
            //在表中间添加
            Node p = head;
            //假如有3 个元素，小于（有效元素 - 1）
            // 即小于2 在链表中间的位置进行添加
            for (int i = 0; i < index - 1; i++) {
                p = p.next;
            }
            node.next = p.next;//旧结点的下一个 给了 新结点的下一个
            p.next = node;//p.next指向新的结点
            // size++;
        }
        size++;
    }


    /**
     * 删除链表中指定的元素element
     *
     * @param element
     */
    @Override
    public void remove(E element) {
        int index = indexOf(element);
        if (index != -1) {
            remove(index);
        }

    }

    /**
     * 删除链表指定角标处的元素
     *
     * @param index
     * @return
     */
    @Override
    public E remove(int index) {
        if (index < 0 || index >= size) {
            throw new IndexOutOfBoundsException("remove index out of bounds");
        }
        E ret = null;
        if (size == 1) {
            //链表只剩一个元素
            ret = head.data;//或者ret = tail.data;
            head = null;
            tail = null;
        } else if (index == 0) {
            //删除表头
            Node del = head;
            ret = del.data; //head.data
            head = del.next;
            del.next = null;
        } else if (index == size - 1) {
            //删除表尾
            Node p = head;
            while (p.next != tail) {
                p = p.next;
            }
            ret = tail.data;
            p.next = null;
            tail = p;
        } else {
            //删除中间某一个元素
            Node p = head;
            for (int i = 0; i < index - 1; i++) {
                // index - 1 获取它的前驱
                p = p.next;
            }
            Node del = p.next;
            ret = del.data;
            p.next = del.next;
            del.next = null;
        }
        size--;
        return ret;
    }

    @Override
    public E get(int index) {
        if (index < 0 || index >= size) {
            throw new ArrayIndexOutOfBoundsException("get index out of bounds");
        }

        if (index == 0) {
            //获取头
            return head.data;
        } else if (index == size - 1) {
            //获取尾
            return tail.data;
        } else {
            //获取中间
            Node p = head;
            for (int i = 0; i < index; i++) {
                //获取它的本身
                p = p.next;
            }
            return p.data;
        }
    }

    /**
     * 修改链表中角标处index元素尾element
     *
     * @param index
     * @param element
     * @return
     */
    @Override
    public E set(int index, E element) {
        if (index < 0 || index >= size) {
            throw new ArrayIndexOutOfBoundsException("set index out of bounds");
        }
        E ret = null;
        if (index == 0) {
            //修改头
            ret = head.data;
            head.data = element;
        } else if (index == size - 1) {
            //修改尾
            ret = tail.data;
            tail.data = element;
        } else {
            //修改中间某一个元素
            Node p = head;
            for (int i = 0; i < index; i++) {
                p = p.next;
            }
            ret = p.data;
            p.data = element;
        }
        return ret;
    }

    @Override
    public int size() {
        return size;
    }

    /**
     * 查找元素在链表中第一次出现的角标
     *
     * @param element
     * @return -1 返回没有找到指定元素
     */
    @Override
    public int indexOf(E element) {
        Node p = head;
        int index = 0;
        while (!p.data.equals(element)) {
            p = p.next;
            index++;
            if (p == null) {
                return -1;
            }
        }
        return index;
    }

    @Override
    public boolean isEmpty() {
        return size == 0 && head == null && tail == null;
    }

    /**
     * 在链表中是否包含元素element
     *
     * @param element
     * @return
     */
    @Override
    public boolean contains(E element) {
        return indexOf(element) != -1;
    }

    @Override
    public void clear() {
        head = null;
        tail = null;
        size = 0;
    }

    @Override
    public void sort(Comparator<E> c) {
        if (c == null) {
            throw new IllegalArgumentException("comparator can not be null");
        }
        int j = 0;
        E e = null;
        for (int i = 1; i < size; i++) {
            e = get(i);
            for (j = i; j > 0 && c.compare(get(j - 1), e) > 0; j--) {
                set(j, get(j - 1));
            }
            set(j, e);
        }
    }

    @Override
    public List<E> subList(int fromIndex, int toIndex) {
        if (fromIndex < 0) {
            throw new IndexOutOfBoundsException("fromIndex must >= 0");
        }
        if (toIndex >= size) {
            throw new IndexOutOfBoundsException("toIndex must < size");
        }
        if (fromIndex > toIndex) {
            throw new IndexOutOfBoundsException("formIndex must <= toIndex");
        }
        LinkedSinglyList<E> subList = new LinkedSinglyList<>();

        for (int i = fromIndex; i <= toIndex; i++) {
            subList.add(get(i));//默认在表尾添加
        }

        return subList;
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder(String.format("LinkedSinglyList:%d [", size));
        if (isEmpty()) {
            sb.append(']');
        } else {
            Node p = head;
            while (true) {
                sb.append(p.data);
                if (p == tail) {
                    sb.append(']');
                    break;
                }
                sb.append(',');
                p = p.next;
            }
        }
        return sb.toString();
    }

    @Override
    public Iterator<E> iterator() {
        return new LinkedListIterator();
    }

    class LinkedListIterator implements Iterator<E> {
        private Node cur = head;

        @Override
        public boolean hasNext() {
            return cur != null;
        }

        @Override
        public E next() {
            E ret = cur.data;
            cur = cur.next;
            return ret;
        }
    }
}

进行测试

import 动态链表.LinkedSinglyList;

import java.util.Comparator;
import java.util.Iterator;

public class LinkedSinglyListTest {
    public static void main(String[] args) {
        LinkedSinglyList<Integer> list = new LinkedSinglyList<>();
        System.out.println(list);
        for (int i = 1; i <= 10; i++) {
            list.add(i);
        }
        System.out.println(list);
        //表头添加元素
        list.add(0, 111);
        list.add(0, 555);
        list.add(0, 200);
        System.out.println(list);
        //在角标5处添加一个元素
        list.add(5, 555);
        System.out.println(list);
        int len = list.size();
        for (int i = 0; i < len; i++) {
            list.remove(0);
        }
        System.out.println(list);
        list.add(100);
        list.add(90);
        list.add(80);
        list.add(70);
        list.add(79);
        System.out.println(list);
        //排序
        list.sort(new Comparator<Integer>() {
            @Override
            public int compare(Integer o1, Integer o2) {
                return o1.compareTo(o2);
            }
        });
        System.out.println(list);
        System.out.println(list.subList(1, 3));
        //使用迭代器遍历
        Iterator<Integer> it = list.iterator();
        while (it.hasNext()) {
            System.out.println(it.next());
        }
    }
}

结果截图：

Comparator() {
@Override
public int compare(Integer o1, Integer o2) {
return o1.compareTo(o2);
}
});
System.out.println(list);
System.out.println(list.subList(1, 3));
//使用迭代器遍历
Iterator it = list.iterator();
while (it.hasNext()) {
System.out.println(it.next());
}
}
}


## 结果
![在这里插入图片描述](https://img-blog.csdnimg.cn/82db2617a9664c5392c909fe38436958.jpeg#pic_center)