警告：StandardWrapperValve [jsp]：用於servlet jsp的PWC1406：Servlet.service（）拋出異常java.lang.NullPointerException

我在非常簡單的JSP/Bean頁面上收到此警告，我在練習考試，我無法克服這一點。警告：StandardWrapperValve [jsp]：用於servlet jsp的PWC1406：Servlet.service（）拋出異常java.lang.NullPointerException

請問有人能指出我的愚蠢嗎？

<html> 
    <head> 

     <title>JSP Page</title> 
    </head> 
    <h1>Enter Details!</h1> 
    <body> 
     <form action="Display.jsp" method="post"> 

      <center> 
       Enter Name :<input type="text" name="Name"/><br/> 
       Etv :<input type="radio" name="Channel" value="Etv" /><br/> 
       Mnet :<input type="radio" name="Channel" value="Mnet" /><br/> 
       Mtv :<input type="radio" name="Channel" value="Mtv" /><br/> 
       FTV :<input type="radio" name="Channel" value="FTV" /><br/> 
       Blue :<input type="checkbox" name="Blue" value="1" /><br/> 
       Yellow :<input type="checkbox" name="Yellow" value="1" /><br/> 
       Green :<input type="checkbox" name="Green" value="1" /><br/> 
       Red :<input type="checkbox" name="Red" value="1" /><br/> 
       <br/> 
       <br/> 

       <input type="submit" value="Submit" /> 
      </center> 
     </form> 

    </body> 
</html>

我的Javabean：

package Beans; 

/* 
* To change this template, choose Tools | Templates 
* and open the template in the editor. 
*/ 

import java.beans.*; 
import java.io.Serializable; 

/** 
* 
* @author Ross 
*/ 
public class NewBean implements Serializable { 

    private String Name; 
    private String Channel; 
    private int Blue; 
    private int Yellow; 
    private int Green; 
    private int Red ; 

    public NewBean() { 

    } 

    public NewBean(String tName,String tChannel,int tBlue,int tYellow,int tGreen,int tRed) { 

    Name=tName; 
    Channel=tChannel; 
    Blue=tBlue; 
    Yellow=tYellow; 
    Green=tGreen; 
    Red=tRed; 
    } 

    public String getName(){ 
     return this.Name; 
    } 
    public String getChannel(){ 
     return this.Channel; 
    } 
    public int getBlue(){ 
     return this.Blue; 
    } 
    public int getYellow(){ 
     return this.Yellow; 
    } 
    public int getGreen(){ 
     return this.Green; 
    } 
    public int getRed(){ 
     return this.Red; 
    } 
    public void setName(String tName){ 
     this.Name = tName; 
    } 
    public void setChannel(String tChannel){ 
     this.Channel = tChannel; 
    } 
    public void setBlue(int tBlue){ 
     this.Blue = tBlue; 
    } 
    public void setYellow(int tYellow){ 
     this.Yellow = tYellow; 
    } 
    public void setGreen(int tGreen){ 
     this.Green = tGreen; 
    } 
    public void setRed(int tRed){ 
     this.Red = tRed; 
    } 
}

我的JSP來顯示的javabean：

<html> 
    <head> 

     <title>Display</title> 
    </head> 
    <body> 
     <h1>Result</h1> 
     <center> 
      <jsp:useBean id="NewBean"class="Beans.NewBean"> 

       <jsp:setProperty name="index" property="Name" param="Name"/> 
       <jsp:setProperty name="index" property="Channel" param="Channel"/> 
       <jsp:setProperty name="index" property="Blue" param="Blue"/> 
       <jsp:setProperty name="index" property="Yellow" param="Yellow"/> 
       <jsp:setProperty name="index" property="Green" param="Green"/> 
       <jsp:setProperty name="index" property="Red" param="Red"/> 
      </jsp:useBean> 
      <b>Displayed.</b> 
      <jsp:getProperty name="index" property="Name"/> 
      <jsp:getProperty name="index" property="Channel"/> 
      <jsp:getProperty name="index" property="Blue"/> 
      <jsp:getProperty name="index" property="Yellow"/> 
      <jsp:getProperty name="index" property="Green"/> 
      <jsp:getProperty name="index" property="Red"/> 
     </center> 

    </body> 
</html>

來源

2012-11-16 user1829002

能否請您粘貼服務器堆棧跟蹤？ –

您應該遵循變量Java命名約定（駱駝）。即

//private String Name; 
private String name;

和

public void setName(String tName){ 
    //this.Name = tName; 
    this.name = tName; 
}

應該由小寫「名稱」屬性被稱爲：

<!-- jsp:setProperty name="index" property="Name" param="Name"/ --> 
<jsp:setProperty name="index" property="name" param="Name"/>

來源

2012-11-16 08:57:37

也是，你的包名應該是小寫。 –

警告：StandardWrapperValve [jsp]：用於servlet jsp的PWC1406：Servlet.service（）拋出異常java.lang.NullPointerException

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