LinkedList_DeleteNodeByIndex.java

public class LinkedList_deleteIndex {
    public class LinkedList<E> {

        private class Node{
            public E e;
            public Node next;

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

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

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

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

        private Node dummyHead;
        private int size;

        public LinkedList(){
            dummyHead = new Node();
            size = 0;
        }

        // 获取链表中的元素个数
        public int getSize(){
            return size;
        }

        // 返回链表是否为空
        public boolean isEmpty(){
            return size == 0;
        }

        // 在链表的index(0-based)位置添加新的元素e
        // 在链表中不是一个常用的操作，练习用：）
        public void add(int index, E e){

            if(index < 0 || index > size)
                throw new IllegalArgumentException("Add failed. Illegal index.");

            Node prev = dummyHead;
            for(int i = 0 ; i < index ; i ++)
                prev = prev.next;

            prev.next = new Node(e, prev.next);
            size ++;
        }

        // 在链表头添加新的元素e
        public void addFirst(E e){
            add(0, e);
        }

        // 在链表末尾添加新的元素e
        public void addLast(E e){
            add(size, e);
        }

        // 获得链表的第index(0-based)个位置的元素
        // 在链表中不是一个常用的操作，练习用：）
        public E get(int index){

            if(index < 0 || index >= size)
                throw new IllegalArgumentException("Get failed. Illegal index.");

            Node cur = dummyHead.next;
            for(int i = 0 ; i < index ; i ++)
                cur = cur.next;
            return cur.e;
        }

        // 获得链表的第一个元素
        public E getFirst(){
            return get(0);
        }

        // 获得链表的最后一个元素
        public E getLast(){
            return get(size - 1);
        }

        // 修改链表的第index(0-based)个位置的元素为e
        // 在链表中不是一个常用的操作，练习用：）
        public void set(int index, E e){
            if(index < 0 || index >= size)
                throw new IllegalArgumentException("Set failed. Illegal index.");

            Node cur = dummyHead.next;
            for(int i = 0 ; i < index ; i ++)
                cur = cur.next;
            cur.e = e;
        }

        // 查找链表中是否有元素e
        public boolean contains(E e){
            Node cur = dummyHead.next;
            while(cur != null){
                if(cur.e.equals(e))
                    return true;
                cur = cur.next;
            }
            return false;
        }

        // 从链表中删除index(0-based)位置的元素, 返回删除的元素
        // 在链表中不是一个常用的操作，练习用：）
        public E remove(int index){
            if(index < 0 || index >= size)
                throw new IllegalArgumentException("Remove failed. Index is illegal.");

            Node prev = dummyHead;
            for(int i = 0 ; i < index ; i ++)
                prev = prev.next;

            Node retNode = prev.next;
            prev.next = retNode.next;
            retNode.next = null;
            size --;

            return retNode.e;
        }

        @Override
        public String toString(){
            StringBuilder res = new StringBuilder();

            Node cur = dummyHead.next;
            while(cur != null){
                res.append(cur + "->");
                cur = cur.next;
            }
            res.append("NULL");

            return res.toString();
        }
    }


    public static void main(String[] args) {
        LinkedList_deleteIndex add = new LinkedList_deleteIndex();
        LinkedList<Integer> linkedList = add.new LinkedList<>();
        for (int i = 0; i < 5; i++) {
            linkedList.add(0, i);
        }

        System.out.println(linkedList);
        System.out.println("remove head:" + linkedList.remove(0));
        System.out.println(linkedList);
        System.out.println("remove mid:" + linkedList.remove(2));
        System.out.println(linkedList);
        System.out.println("remove tail:" + linkedList.remove(2));
        System.out.println(linkedList);

    }
}