实现自己的LinkedList

来源：互联网发布：linux 窗口编程工具编辑：程序博客网时间：2024/05/22 15:21
public class SimpleLinkedList<T>{    private static class Node<T>    {        T data;        Node<T> next;        public Node(T t, Node<T> n)        {            this.data = t;            this.next = n;        }        public String toString()        {            return "(data=" + data + ")";        }    }    private int size = 0;    /**     * 记录list被修改结构的次数     */    private int modCount = 0;    private Node<T> head;    public SimpleLinkedList(int size)    {        this.size = size;        clear();    }    /**     * clear the whole list     */    public void clear()    {        head = new Node<T>(null, null);        this.size = 0;        modCount++;    }    public boolean isEmpty()    {        return size == 0;    }    /***     * 每次都在最前端插入<br>     *      * @param x     * @return     */    public boolean add(T x)    {        Node<T> t = new Node<T>(x, head.next);        head.next = t;        size++;        modCount++;        return true;    }    /***     * id表示第id个元素,head为第0个,依次类推<br>     *      * @param id     * @return     */    public T get(int id)    {        if (id > size)            return null;        Node<T> temp;        for (temp = head; id > 0; temp = temp.next, id--)        {        }        return temp.data;    }    public T set(int id, T newValue)    {        if (id > size || id < 1)            return null;        Node<T> temp;        for (temp = head; id > 0; temp = temp.next, id--)        {        }        T oldValue = temp.data;        temp.data = newValue;        return oldValue;    }    public T remove(int id)    {        Node<T> temp = head;        for (; id > 1; temp = temp.next, id--)        {        }        T value = temp.next.data;        temp.next = temp.next.next;        size--;        return value;    }    /***     * 借助先进先出队列进行reverse操作<br>     * 逻辑简单,但是效率不高<br>     *      * @return     */    public void reverse_1()    {        // Stack<Node<T>> stack = new Stack<Node<T>>();        Queue<Node<T>> queue = new LinkedList<>();        Node<T> te = head;        while (te.next != null)        {            te = te.next;            queue.add(te);        }        /**         * 清空原来的链表,重新建表<br>         */        clear();        while (!queue.isEmpty())        {            add(queue.poll().data);        }    }    /***     * 反转链表 基本思想:逐个节点拆开,建一个新的list<br>     */    public void reverse_2()    {        Node<T> newHead = new Node<T>(null, null);        while (head.next != null)        {            Node<T> temp = head.next;            head.next = head.next.next;            temp.next = newHead.next;            newHead.next = temp;        }        head = newHead;    }    public String toString()    {        StringBuilder b = new StringBuilder();        Node<T> temp = head.next;        for (int i = 0; i < size; i++, temp = temp.next)        {            b.append(temp.toString() + "->");        }        b.append("NULL");        return b.toString();    }    public Iterator<T> iterator()    {        return new LinkedListIterator();    }    private class LinkedListIterator implements Iterator<T>    {        Node<T> current = head;        @Override        public boolean hasNext()        {            return current.next != null;        }        @Override        public T next()        {            if (hasNext())            {                current = current.next;                return current.data;            }            return null;        }    }    public static void main(String[] ar)    {        SimpleLinkedList<Integer> list = new SimpleLinkedList<Integer>(10);        for (int i = 0; i < 10; i++)        {            list.add(i);        }        System.out.println(list);        System.out.println("Get an element : (data=" + list.get(6) + ")");        // System.out.println("Remove an element : (data=" + list.remove(6) +        // ")");        System.out.println("Remove an element : (data=" + list.set(6, 110) + ")");        System.out.println("\nOriginal list : " + list);        list.reverse_1();        System.out.println("List after reversed_1 : " + list);        list.reverse_2();        System.out.println("List after reversed_2 : " + list);        /***         * Iterator         */        Iterator<Integer> it = list.iterator();        while (it.hasNext())            System.out.println("it.next = " + it.next());    }}
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