In debug a javabean, how check it is giving to other component CORRECT data-DAO/pools

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04-25-2010, 01:13 PM
lse123

In debug a javabean, how check it is giving to other component CORRECT data-DAO/pools

textbook example 12-3(david pasons java/xml) - DAO / DB-POOL / TOMCAT

At localhost
http://localhost:8080/jspadv/webhome...listclaims.jsp
I do NOT know, how debug? In debug a javabean, how check it is giving to other component CORRECT data?
The below means not find data ...? in db?

Code:

org.apache.jasper.JasperException: javax.el.ELException: Error reading 'claims' on type com.webhomecover.beans.ClaimCollection org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:522) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:416) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267) javax.servlet.http.HttpServlet.service(HttpServlet.java:717) root cause javax.el.ELException: Error reading 'claims' on type com.webhomecover.beans.ClaimCollection javax.el.BeanELResolver.getValue(BeanELResolver.java:66) javax.el.CompositeELResolver.getValue(CompositeELResolver.java:53) org.apache.el.parser.AstValue.getValue(AstValue.java:118) org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:186) org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:925) org.apache.jsp.listclaims_jsp._jspx_meth_c_005fforEach_005f0(listclaims_jsp.java:125) org.apache.jsp.listclaims_jsp._jspService(listclaims_jsp.java:99) org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) javax.servlet.http.HttpServlet.service(HttpServlet.java:717) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267) javax.servlet.http.HttpServlet.service(HttpServlet.java:717) root cause java.lang.NullPointerException com.webhomecover.dao.ClaimDAO.readClaims(Unknown Source) com.webhomecover.model.ModelFacade.getClaims(Unknown Source) com.webhomecover.beans.ClaimCollection.getClaims(Unknown Source) sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) java.lang.reflect.Method.invoke(Method.java:597) javax.el.BeanELResolver.getValue(BeanELResolver.java:62) javax.el.CompositeELResolver.getValue(CompositeELResolver.java:53) org.apache.el.parser.AstValue.getValue(AstValue.java:118) org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:186) org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:925) org.apache.jsp.listclaims_jsp._jspx_meth_c_005fforEach_005f0(listclaims_jsp.java:125) org.apache.jsp.listclaims_jsp._jspService(listclaims_jsp.java:99) org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) javax.servlet.http.HttpServlet.service(HttpServlet.java:717) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267) javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

Code:

<?xml version="1.0"?>  <jsp:root xmlns:jsp="http://java.sun.com/JSP/Page" xmlns:c="http://java.sun.com/jsp/jstl/core" version="2.0"> <jsp:directive.page isELIgnored="false" /> <jsp:directive.page contentType="text/html"/> <jsp:output omit-xml-declaration="false" doctype-root-element="html" doctype-public="-//W3C//DTD XHTML 1.1//EN" doctype-system="http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd" /> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en"> <head> <link href="webhomecover.css" rel="stylesheet" type="text/css" /> <title>Insurance Claims</title> </head> <body> <p>Here is a list of claims</p> <table> <tr> <th>reference</th><th>description</th><th>amount</th><th>approved</th><th>claimDate</th> </tr> <jsp:useBean id="claimCollection" class="com.webhomecover.beans.ClaimCollection" /> <c:forEach var="claim" items="${claimCollection.claims}"> <tr> <td><c:out value="${claim.reference}" /></td> <td><c:out value="${claim.description}" /></td> <td><c:out value="${claim.amount}" /></td> <td><c:out value="${claim.approved}" /></td> <td><c:out value="${claim.claimDate}" /></td> </tr> </c:forEach> </table> </body> </html> </jsp:root>
04-25-2010, 03:54 PM
Tolls

Test the ClaimCollections bean in isolation.
Does it work?
04-25-2010, 06:32 PM
lse123

is it faults where clause?

claims is a list of claim.
String x=new String(); provides empty string or needed inside parenthesis "" (doublequotes)?

is it faults where clause?

Code:

//com.webhomecover.beans.ClaimCollection package com.webhomecover.beans; import java.util.*; import com.webhomecover.model.ModelFacade; import com.webhomecover.model.Claim; public class ClaimCollection { private String whereClause = new String(); public String getWhereClause() { return whereClause; } public void setWhereClause(String whereClause) { this.whereClause = whereClause; } public Collection<Claim> getClaims() { Collection<Claim> claims = ModelFacade.getClaims(whereClause); return claims; } }

Code:

package com.webhomecover.model; import com.webhomecover.dao.ClaimDAO; import java.util.Collection; public class ModelFacade { public static Collection<Claim> getClaims(String whereClause) { // if no 'where' clause string is passed in, create an empty string if(whereClause == null) { whereClause = new String(); } ClaimDAO cdao = new ClaimDAO(); Collection<Claim> claimCollection = cdao.readClaims(whereClause); return claimCollection; } }

Code:

// com.webhomecover.dao.ClaimDAO.java ..................... public Collection<Claim> readClaims(String whereClause) { Collection<Claim> claims = new ArrayList<Claim>(); try { getConnection(); Statement statement = connection.createStatement(); ResultSet results = statement.executeQuery("SELECT * FROM claim " + whereClause); String reference = null; String description = null; double amount = 0.0; boolean approved = false; java.sql.Date claimDate = null; Claim claim = null; while(results.next()) { reference = results.getString("reference"); description = results.getString("description"); amount = results.getDouble("amount"); approved = results.getBoolean("approved"); claimDate = results.getDate("claimDate"); claim = new Claim(); claim.setReference(reference); claim.setDescription(description); claim.setAmount(amount); claim.setApproved(approved); claim.setClaimDate(claimDate); claims.add(claim); } results.close(); results = null; statement.close(); statement = null; connection.close(); connection = null; } catch(SQLException e) { e.printStackTrace(); } finally { cleanUp(); } return claims; } .....................
04-26-2010, 09:57 AM
Tolls

Does that work in isolation, though?
If not, then where is it going wrong?
04-26-2010, 11:06 AM
lse123

by saying isolation you mean get out off app?
04-26-2010, 11:13 AM
Tolls

Yes.
That's how you test things.
Run them by themselves, especially stuff interacting with a database.
Otherwise how do you know if what you've written actually works?
04-26-2010, 01:47 PM
lse123

there is another file in app:
go and run it?
pools exist and in desktop app connections (from 4 types of db conn which pools permited?) ?

Code:

// ClaimDAOTest.java package com.webhomecover.tests; import java.sql.*; import java.util.*; import com.webhomecover.dao.*; import com.webhomecover.model.*; public class ClaimDAOTest { public static void main(String[] args) { ClaimDAO cdao = new ClaimDAO(); Collection<Claim> c = cdao.readClaims(""); Iterator<Claim> iter = c.iterator(); System.out.println("id\tdescription\tamount\tapproved\tclaimDate"); while(iter.hasNext()) { Claim claim = iter.next(); System.out.println(claim.getReference() + "\t" + claim.getDescription() + "\t" + claim.getAmount() + "\t" + claim.getApproved() + "\t" + claim.getClaimDate()); } } }
04-26-2010, 02:19 PM
Tolls

Does that work?
04-26-2010, 04:37 PM
lse123

since the main app is web app and this not(ClaimDAOTest.java), how to run? requires running web server to run it? I use db conn pools...
04-26-2010, 04:54 PM
Tolls

I have no idea what this needs to run...it's your code!

If you have connection pools I'm sure, if you've written the code suitably openly, you should be able to dummy the connection stuff. Even if it's something as basic as redoing getConnection() to simply build a connection and not use a pool.

You're trying to see if this code works.

By the way, looking at your stuff again...doing SQL in a for loop like that is not a good idea. Go through a servlet which gets the arraylist and passes it to the JSP in the request. I'm can't guarantee it, but I would think the current way you have things here might hit the db everytime it loops. Depends how the for-each works.
04-26-2010, 10:56 PM
lse123

I will test code tomorrow, but since, this is a textbook example inside the text, must be correct, any tip about this for the code(additional)?
04-27-2010, 09:09 AM
Tolls

I wouldn't bet on it being correct.

But, as I said, that SQL query in a for-each simply looks wrong.
The usual technique is to have a servlet (and business layer and db layer) get the data for the JSP to display.
04-29-2010, 07:27 PM
lse123

you may find the complete app I refer at

Cengage Learning -Dynamic Web Application Development

Examples:Chapter 12: 12-3 folder [database in 12-1]

I am currently debugging...
04-30-2010, 08:57 AM
Tolls

If they're suggesting you do your for-each like that, with essentially a DAO supplying the results directly, then I would suggest looking for a different course to work through.
04-30-2010, 11:22 AM
r035198x

I'm late here but the trace says you have a nullpointer in your readClaims method.
In that method you do

Code:

results.close(); results = null; statement.close(); statement = null; connection.close(); connection = null;

then in the finally you call a method called cleanUp. What does that cleanUp method do?
04-30-2010, 11:30 AM
Tolls

This was why I was trying to get them to actually test the database gubbins in isolation.
04-30-2010, 12:06 PM
lse123

The role of this method is to attempt to close any resourses that may have been left open by exceptions being thrown...

can you download and try code from textbook site above, must be correct?
04-30-2010, 12:15 PM
Tolls

If that's the way they've written their code then I would question the quality of the course.
They are not closing resources in a finally block (ie resultset and statement).

I'm not going to grabn code and try it out...since you're doing the course you need to figure out whether what you have matches the course code. If it doesn't then there's your problem.
04-30-2010, 12:21 PM
lse123

Using db conn pools,
.........
private static final String DATASOURCE_NAME = "java:comp/env/jdbc/webhomecoverds";
.........
this[vars] must unique among ALL Tomcat's Web Apps (localhost)? or not required...?
04-30-2010, 12:28 PM
lse123

// ClaimDAOTest.java in #7

must run from C:\JSPAdv\webhomecover\WEB-INF\classes

WHAT CLI COMMAND TO USE?

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