userlinklist.java

网络通信系统

public class UserLinkList {//用户链表操作
  Node head;
  Node pointer;
  int count;
  
  public UserLinkList(){//构造用户链表
	head = new Node();
	head.next = null;
	pointer = null;
	count = 0;
  }
  
  public void addUser(Node n){//添加用户
	pointer = head;
	while(pointer.next != null){
	  pointer = pointer.next;	 
	}
	pointer.next = n;
	n.next = null;
	count++;
  }
  
  public void delUser(Node n){//删除用户
	pointer = head;
	while(pointer.next != null){
	  if(pointer.next == n){
		pointer.next = n.next;
		count--;
		break;
	  }
	  pointer = pointer.next;
	}
  }
  
  public int getCount(){//返回用户数
	return count;  
  }
  
  public Node findUser(String username){//根据用户名查找用户
	if(count == 0) return null;
	pointer = head;
	while(pointer.next != null){
	  pointer = pointer.next;
	  if(pointer.username.equalsIgnoreCase(username)){
		return pointer;  
	  }
	}
	return null;
  }
  
  public Node findUser(int index){//根据索引查找用户
	if(count == 0) return null;
	if(count < 0) return null;
	pointer = head;
	int i = 0;
	while(i < index+1){
	  if(pointer.next != null) pointer = pointer.next;
	  else return null;
	  i++;
	}
	return pointer;
  }
}