Java链表插入删除

public class Lianbiaoinsertdeletesort {
	public static void main(String[] args) {
		linklist list = new linklist();
		list.set(1);
		list.set(2);
		list.set(3);
		list.set(4);
		list.display();
		list.insert(9, 3);
		list.display();
		list.delete(4);
		list.display();
	}

}

class linklist {
	private class Node {
		private Object obj;
		private Node next = null;

		Node(Object obj) {
			this.obj = obj;
		}
	}

	Node first = null;
	Node last = first;
//创建
	public void set(Object obj) {

		Node node = new Node(obj);
		if (first == null)
			first = node;
		else
			last.next = node;
		last = node;
	}
//插入
       public void insert(Object obj,int index) {
		Node cur=first;
		int j=0;
		while(cur!=null&&j<index-2){    
	        cur=cur.next;    
	        j++;    
	    }
		Node sert=new Node(obj);
		sert.next=cur.next;
		cur.next=sert;
	}
//删除
       public void delete(int index) {
		Node cur=first;
		int j=0;
		while(cur!=null&&j<index-2) {
			cur=cur.next;
			j++;
		}
	Node t=cur.next;
        cur.next=cur.next.next;
        t=null;
        System.gc();  //回收内存，将对象指向空，调用system.gc()
		
	}
//打印
	public void display() {
		if (first == null) {

			System.out.println("empty");
		}
		Node cur = first;
		while (cur != null) {
			System.out.print(cur.obj.toString() + "->");
			cur = cur.next;
		}
		System.out.println();
	}

}