Attempted a bean operation on a null object这个什么错误

purecoffee 2005-05-26 10:51:41

我在做那个Struts Kick Start书上的例子：
animalinput.jsp
<%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" errorPage="" %>
<!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=gb2312">
<title>无标题文档</title>
</head>

<body>
<form name="form1" method="post" action="animaldisplay.jsp">
<table width="100%" border="0">
<tr>
<td> </td>
</tr>
<tr>
<td><p>Common Name :
<input name="commonname" type="text" id="commonName">
</p>
<p>Species Name:
<input name="speciesname" type="text" id="speciesName">
</p>
<p>Adult Height:
<input name="adultheight" type="text" id="adultHeight">
</p>
<p>Adult Weight:
<input name="adultweight" type="text" id="adultWeight">
</p>
<p>Top Speed:
<input name="topspeed" type="text" id="topSpeed">
</p>
<p>Description:<br>
<textarea name="description" cols="50" rows="5" id="description"></textarea>
</p></td>
</tr>
<tr>
<td><div align="center">
<input type="submit" name="Submit" value="提交">
</div></td>
</tr>
</table>
</form>
</body>
</html>

animaldisplay.jsp
<%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" errorPage="" %>
<jsp:useBean id="animal" scope="request" class="demo.Animal"/>
<jsp:setProperty name = "animal" property="*"/>
<!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=gb2312">
<title>无标题文档</title>
</head>

<body>
<table width="100%" border="0">
<tr>
<td> </td>
</tr>
<tr>
<td><p><h2>Common Name :<jsp:getProperty name ="animal " property="commonName"/></h2>

</p>
<p>Species Name:
<jsp:getProperty name="animal" property="speciesName"/>
</p>
<p>Adult Height:
<jsp:getProperty name="animal" property="adultHeight"/>
</p>
<p>Adult Weight:
<jsp:getProperty name="animal" property="adultWeight"/>
</p>
<p>Top Speed:
<jsp:getProperty name="animal" property="topSpeed"/>
</p>
<p>Description:<br>
<textarea name="description" cols="50" rows="5" id="description">
<jsp:getProperty name="animal" property="description"/>
</textarea>
</p></td>
</tr>
<tr>
<td><div align="center">

</div></td>
</tr>
</table>

</body>
</html>

Animal.java
package demo;

/**
*
* @author Administrator
* @version 2005-5-25
* @see
*/
public class Animal {
String commonName = null;
String speciesName = null;
float adultHeight = 0;
float adultWeight = 0;
int topSpeed = 0;
String description;

/**
* @return 返回 adultHeight。
*/
public float getAdultHeight() {
return adultHeight;
}
/**
* @param adultHeight 要设置的 adultHeight。
*/
public void setAdultHeight(float adultHeight) {
this.adultHeight = adultHeight;
}
/**
* @return 返回 adultWeight。
*/
public float getAdultWeight() {
return adultWeight;
}
/**
* @param adultWeight 要设置的 adultWeight。
*/
public void setAdultWeight(float adultWeight) {
this.adultWeight = adultWeight;
}
/**
* @return 返回 commonName。
*/
public String getCommonName() {
return commonName;
}
/**
* @param commonName 要设置的 commonName。
*/
public void setCommonName(String commonName) {
this.commonName = commonName;
}
/**
* @return 返回 description。
*/
public String getDescription() {
return description;
}
/**
* @param description 要设置的 description。
*/
public void setDescription(String description) {
this.description = description;
}
/**
* @return 返回 speciesName。
*/
public String getSpeciesName() {
return speciesName;
}
/**
* @param speciesName 要设置的 speciesName。
*/
public void setSpeciesName(String speciesName) {
this.speciesName = speciesName;
}
/**
* @return 返回 topSpeed。
*/
public int getTopSpeed() {
return topSpeed;
}
/**
* @param topSpeed 要设置的 topSpeed。
*/
public void setTopSpeed(int topSpeed) {
this.topSpeed = topSpeed;
}
public static void main(String[] args) {
}
}
运行的时候出现标题的错误！！高手帮帮忙

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