Java容器---MyLinkedList

自定义容器LinkedList，实现部分功能

    1.创建Node类，存放节点信息

/**
 * 每个节点内三个对象表示
 * previous 前一个节点位置
 * obj 当前节点数据信息
 * next 下一个节点位置
 * @author Administrator
 *
 */
public class Node {

	 Node previous;
	 Object obj;
	 Node next;
	
	public Node(){
		
	}
	
	public Node(Node previous,Object obj,Node next){
		super();
		this.previous = previous;
		this.obj = obj;
		this.next = next;
	}

	public Object getPrevious() {
		return previous;
	}

	public void setPrevious(Node previous) {
		this.previous = previous;
	}

	public Object getObj() {
		return obj;
	}

	public void setObj(Object obj) {
		this.obj = obj;
	}

	public Object getNext() {
		return next;
	}

	public void setNext(Node next) {
		this.next = next;
	}
	
}

    2. 实现LinkedList

/**
 * 编程实现LinkedList
 * 
 * @author Administrator
 *
 */
public class MyLinkedList {

	private Node first;
	private Node last;
	private int size;

	public MyLinkedList() {

	}

	public int size() {
		return size;
	}

	// 在链表尾部增加指定对象
	public void add(Object obj) {
		Node n = new Node();
		// 链表头是否为空
		if (first == null) {

			n.setPrevious(null);
			n.setObj(obj);
			n.setNext(null);
			first = n;
			last = n;

		} else {
			// 向last节点后增加新的节点
			n.setPrevious(last);
			n.setObj(obj);
			n.setNext(null);

			last.setNext(n);

			last = n;

		}
		size++;
	}

	// 向指定索引位置增加对象，新节点的对应关系为:previous指向索引位置节点的前一个节点,next指向索引位置节点
	public void add(int index, Object obj) {
		rangeCheck(index);
		Node temp = node(index);

		Node up = temp.previous;
		Node newNode = new Node();
		newNode.obj = obj;

		if (temp != null) {

			newNode.previous = up;
			up.next = newNode;

			newNode.next = temp;
			temp.previous = newNode;
			size++;
		}

	}

	public void set(int index, Object obj) {
		rangeCheck(index);
		Node temp = node(index);

		if (temp != null) {
			temp.obj = obj;
		}
	}

	public Object get(int index) {
		rangeCheck(index);
		Node temp = node(index);
		if (temp != null) {
			return temp.obj;
		} else {
			return null;
		}

	}

	// 移除索引位置节点,1 2 3,将1的下一个设置为3,3的上一个设置为1,实现双向,移除2位置
	public void remove(int index) {
		Node temp = node(index);
		if (temp != null) {
			// 索引位置节点的上一个节点
			Node up = temp.previous;
			// 索引位置节点的下一个节点
			Node down = temp.next;
			// 上一个节点的next节点位置设置为当前节点的下一个,同理操作下一个节点,实现移除索引位置节点
			up.next = down;
			down.previous = up;
		}
		size--;
	}

	public void clear() {
		Node temp = new Node();
		if (first != null) {
			temp = first;
			for (int i = 0; i < size - 1; i++) {
				temp.obj = null;
				temp = temp.next;
				size--;

			}

		}

	}

	public void rangeCheck(int index) {
		if (index < 0 || index > size - 1) {
			try {
				throw new Exception();
			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}

	// 寻找节点
	public Node node(int index) {
		rangeCheck(index);
		Node temp = null;
		
		if (first != null) {
			
			//size=50;[0,49],寻找第2个和寻找第48个节点的方法优化分析
			//一个简单的优化算法:将index与size/2(szie>>1)进行比较,如果小於则从0开始遍历,如果大於则从49开始向前遍历
			if (index<(size>>1)) {
				temp = first;
				for (int i = 0; i < index; i++) {
					temp = temp.next;
				}
			}else{
				temp = last;
				for (int i = size-1; i > index; i--) {
					temp = temp.previous;
				}
			}
			
		}
		return temp;
	}

	public static void main(String[] args) {
		MyLinkedList list = new MyLinkedList();
		list.add("aaa");
		list.add(111);
		list.add(555);
		list.add(1, "ddd");
		list.set(1, 444);
		
		
		System.out.println(list.get(1));
//		for (int i = 0; i < list.size(); i++) {
//			System.out.println(list.get(i));
//		}

	}

}