Can't use : “Bean cannot be resolved to a type”

I'm just playing around with JSP. I just wanted to test some <jsp:useBean> stuff, but I can't. Every time if I'm using <jsp:useBean>, I get an error. Even if I just have this, I get an error:

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>Test</title>
  </head>
  <body>
    <jsp:useBean id="mybean" class="Users" scope="session" >
      <jsp:setProperty name="mybean" property="name" value="Hello world" />
    </jsp:useBean>
  </body>
</html>

Without the <jsp:useBean> it runs fine. With the <jsp:useBean> I get an error like:

Servlet.service() for servlet [jsp] in context with path [/JSPTest] threw exception [Unable to compile class for JSP: 

An error occurred at line: 10 in the jsp file: /index.jsp
Users cannot be resolved to a type
7:     <title>Insert title here</title>
8:   </head>
9:   <body>
10:     <jsp:useBean id="mybean" class="Users" scope="session" >
11:       <jsp:setProperty name="mybean" property="name" value="Hello world" />
12:     </jsp:useBean>
13:   </body>

I am using Eclipse, Tomcat 7.0.23 and Java 1.7.0_01.

Any ideas?

PS: I had to change the port 8xxx to 9xxx because the oracle DB is using the standard 8xxx. But that's likely not the cause of the problem.

You need to put classes in a package in order to be able to use them in another classes. Classes in the default package are invisible to classes which are by itself in a package (like as the JSP would end up).

So, give the Users class a package like so:

package com.example;

public class Users {
    // ...
}

Recompile and put it in /WEB-INF/classes/com/example/Users.class.

Then you can reference it as follows:

<jsp:useBean id="myBean" class="com.example.Users" />

Unrelated to the concrete problem, having a plural as class name of an entity is usually a smell. Does a single instance of that class really represent multiple users? Why would you not have a List<User> for example? Or does it actually represent a single user? It should then be named User instead.

来源：https://stackoverflow.com/questions/8329451/cant-use-jspusebean-bean-cannot-be-resolved-to-a-type

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Can't use <jsp:useBean>: “Bean cannot be resolved to a type”