java.lang.NumberFormatException: null错误。

Question

java.lang.NumberFormatException: null
java.lang.Integer.parseInt(Integer.java:417)
java.lang.Integer.parseInt(Integer.java:499)
com.jsoft.servlet.UserServlet.doAll(UserServlet.java:79)
com.jsoft.servlet.UserServlet.doDelete(UserServlet.java:99)
com.jsoft.servlet.UserServlet.doPost(UserServlet.java:46)
com.jsoft.servlet.UserServlet.doGet(UserServlet.java:25)
javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
javax.servlet.http.HttpServlet.service(HttpServlet.java:723)

代码：

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doPost(request,response);
}

/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub

String f=request.getParameter("f");

if("login".equals(f)){
doLogin(request,response);
return;
}
if("all".equals(f)){
doAll(request,response);
return;
}
if("delete".equals(f)){
doDelete(request,response);
return;
}
if("add".equals(f)){
doAdd(request,response);
return;
}
}
protected void doLogin(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

String loginName=request.getParameter("userid");
String pass=request.getParameter("psword");

UserServise u=new UserServise();
User user=u.login(loginName, pass);

if(user.getLoginName()!=null)
{
HttpSession session=request.getSession();
session.setAttribute("uname", user.getUserName());
//重定向
response.sendRedirect("Main.htm");
}

else{
//重定向
//response.sendRedirect("error.html");
request.setAttribute("message", "用户名或密码错误！");
request.getRequestDispatcher("login.jsp").forward(request,response);
}
}

protected void doAll(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
int page=Integer.parseInt(request.getParameter("page"));
if(page<1){
page=1;
}
UserServise u=new UserServise();
PageList<User> list=u.all(page);
if(list==null){
request.setAttribute("message", "值为空");
}
else{
request.setAttribute("l", list);
request.getRequestDispatcher("system/USER1001.jsp").forward(request, response);
}
}

protected void doDelete(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
int id=Integer.parseInt(request.getParameter("id"));
UserServise u=new UserServise();
if(u.delete(id)){
System.out.println("成功！");
doAll(request, response);
}
else{
System.out.println("失败！");
doAll(request, response);
}
}

Answer 1

int page=Integer.parseInt(request.getParameter("page")); 感觉 是这里有问题 ，是不是没有初始值 建议判断下 在转型

追问

有初始值的，初始值是1

追答

debug 单步下 ，哪里报错，

其实报错里面已经有提示了

com.jsoft.servlet.UserServlet.doAll(UserServlet.java:79)
com.jsoft.servlet.UserServlet.doDelete(UserServlet.java:99)
com.jsoft.servlet.UserServlet.doPost(UserServlet.java:46)
com.jsoft.servlet.UserServlet.doGet(UserServlet.java:25)

Answer 2

java.lang.NumberFormatException: null