java.lang.NumberFormatException: For input string: ""问题

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

java.lang.NumberFormatException: For input string: ""
java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
java.lang.Integer.parseInt(Integer.java:468)
java.lang.Integer.parseInt(Integer.java:497)
gao.servlet.ManagerServlet.doGet(ManagerServlet.java:30)
gao.servlet.ManagerServlet.doPost(ManagerServlet.java:322)
javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
这是报错页面是说ManagerServlet的30和322有错么
package gao.servlet;

import java.io.IOException;
import gao.java.*;
import java.util.*;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class ManagerServlet extends HttpServlet {


public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

request.setCharacterEncoding("utf-8");
response.setContentType("text/html");
response.setCharacterEncoding("utf-8");
DBHandle dbh=new DBHandle();
int pageSize=10;
int pageCount=0;
int pageNow=1;
int rowCount=0;/
String flag=request.getParameter("flag");
String pageNowStr=request.getParameter("pageNow");
if(pageNowStr==null||pageNowStr=="") pageNowStr="1";
pageNow=Integer.parseInt(pageNowStr.trim());