cannot activate a web application with database

[Cathy Valdez]

The topic is Integrating a Web Application With a Database
Below are softwares installed in my PC:
OS=Windows98
Tomcat v. 4.1.27.exe
J2SE/JDK v. 1.3.1
mysql
mysql-connector-java

Below is the content of Autoexec.bat:

rem - By Windows Setup - C:\WINDOWS\COMMAND\MSCDEX /V /D:ATAPI_CD /M:10
set PATH=c:\jdk1.3.1\bin;%PATH%
set CLASSPATH=%CLASSPATH%;.;c:\ServletDevel\database;c:\ServletDevel\database\lib\conn_pool.jar;c:\Tomcat\common\lib\servlet.jar;c:\mysql-connector-java\mysql-connector-java-3.0.9-stable-bin.jar
set JAVA_HOME=c:\jdk1.3.1

Compilation of servlet files below were successful.
InitializeConnectionPool.java
ScrambleGameServlet.java
NamingService.java
ScrambleGameService.java
Word.java
WordCategory.java
WordCategoryDAO.java
WordCategoryService.java
WordDAO.java

Below is the content of the deployment descriptor -web.xml:

<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/j2ee/dtds/web-app_2_3.dtd">
<web-app>
    <display-name>SL-314 Database Exercise #1</display-name>
    <description>
This WebApp demonstrates a typical servlet design using Connection
Pooling and Data Access Objects to interface with a database.
    </description>
    <!--
      Step: Enter the parameters for constructing the Connection Pool.
      -->
    <context-param>
       <param-name>jdbcDriver</param-name>
       <param-value>com.mysql.jdbc.Driver</param-value>
    </context-param>
    <context-param>
       <param-name>jdbcURL</param-name>
       <param-value>jdbc:mysql://localhost/wordgames</param-value>
    </context-param>
    <context-param>
       <param-name>jdbcUserName</param-name>
       <param-value>root</param-value> 
    </context-param>
    <context-param>
       <param-name>jdbcPassword</param-name>
       <param-value>aprfeb</param-value> 
    </context-param>
    <context-param>
       <param-name>minimumConnections</param-name>
       <param-value>1</param-value>
    </context-param>
    <context-param>
       <param-name>maximumConnections</param-name>
       <param-value>5</param-value>
    </context-param>
    <!--
      Step: Enter the servlet context listener class name
      -->
    <listener>
       <listener-class>sl314.web.InitializeConnectionPool</listener-class>
    </listener>
    <servlet>
        <servlet-name>WordScrambleServlet</servlet-name>
        <servlet-class>sl314.web.ScrambleGameServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>WordScrambleServlet</servlet-name>
        <url-pattern>/wordScramble</url-pattern>
    </servlet-mapping>
    <error-page>
        <exception-type>sl314.util.sql.ConnNotAvailException</exception-type>
        <location>/error/server_busy.html</location>
    </error-page>
    <error-page>
        <exception-type>sl314.util.sql.ShuttingDownException</exception-type>
        <location>/error/server_shutdown.html</location>
    </error-page>
</web-app>

The database wordgames above is located at the directory below:

c:\mysql\data\wordgames

Below are files inside the directory above:
wordcategory.frm
wordcategory.MYI
wordcategory.MYD
word.frm
word.MYI
word.MYD
wordhint.frm
wordhint.MYI
wordhint.MYD

To activate the Scramble Game Servlet, using a Web Browser, I entered the URL below:

http://localhost:8080/database/index.html

Below is the displayed page form for the URL above:
Duke's Arcade
Select from one of the following games:

Word Scramble
When I clicked the Word Scramble above, errors below occured:

 HTTP Status 500 - 
--------------------------------------------------------------------------------
type Exception report
message 
description The server encountered an internal error () that prevented it from fulfilling this request.
exception 
javax.servlet.ServletException
at sl314.web.ScrambleGameServlet.showCategories(ScrambleGameServlet.java:54)
at sl314.web.ScrambleGameServlet.doGet(ScrambleGameServlet.java:29)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:740)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:256)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2416)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:171)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:172)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:223)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:601)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:392)
at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:565)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:619)
at java.lang.Thread.run(Thread.java:484)
root cause 
java.lang.NullPointerException
at sl314.domain.WordCategoryDAO.selectAllCategories(WordCategoryDAO.java:38)
at sl314.domain.WordCategoryService.getCategories(WordCategoryService.java:16)
at sl314.web.ScrambleGameServlet.showCategories(ScrambleGameServlet.java:43)
at sl314.web.ScrambleGameServlet.doGet(ScrambleGameServlet.java:29)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:740)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:256)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2416)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:171)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:172)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:223)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:601)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:392)
at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:565)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:619)
at java.lang.Thread.run(Thread.java:484)
--------------------------------------------------------------------------------
Apache Tomcat/4.1.27

What do errors above mean? What should I do to correct those errors so to run this Web application with database in my PC? Can anybody there help?
Any suggestions would greatly be appreciated.
Thanks in advance.
Regards,
Cathy

[Bear Bibeault]

Please do not cross-post the same question in multiple forums.
bear

[Jamie Robertson]

Originally posted by Bear Bibeault:
Please do not cross-post the same question in multiple forums.
bear

This is probably best suited for the servlet forum, but this is what I can make of it:
sl314.web.ScrambleGameServlet.showCategories(ScrambleGameServlet.java:54)
- looks like a problem at line 54 of the showCategories method in your SCrambleGameServlet class.
root cause java.lang.NullPointerException
- looks like you used an object without initializing it.

To fix: go to line 54 in the affected object, and find out where it missed being initialized. When you find where it should have been initialized, initialize it!
Nothing to do with JDBC though
Jamie