I have a simple for with a text input field, submit button and select
components
in the form.
There is a corresponding ActionForm and Action class.
If I don't populate the ActionErrors object in validate, everything works
great.
If I do populate the ActionErrors object, I get a NullPointerException in
the browser like so:
java.lang.NullPointerException
at
org.apache.struts.taglib.html.OptionsTag.getIterator(OptionsTag.java:366)
Not that it matters, but I am validating the text input field only.
If I comment out the select component in the JSP page and put an invalid
entry in
the text field, the error shows up fine.
I don't see the relationship between these two things.
Here is the code in its entirety.
Much obliged.
David
----------------------------------------------------------------------------
-------------------------------------------
<struts-config>
<!-- ========== Form Bean Definitions ===================================
-->
<form-beans>
<!-- meter form bean -->
<form-bean name="meterForm"
type="rwebstruts.MeterForm"/>
</form-beans>
<!-- ========== Global Forward Definitions ==============================
-->
<global-forwards>
<forward name="meter" path="/meter.jsp"/>
</global-forwards>
<!-- ========== Action Mapping Definitions ==============================
-->
<action-mappings>
<!-- Process a MeterHost addition/removal -->
<action path="/meter"
type="rwebstruts.MeterAction"
name="meterForm"
scope="request"
input="/meter.jsp">
</action>
</action-mappings>
</struts-config>
----------------------------------------------------------------------------
---------------------------------------------------------
<%@ page language="java" %>
<%@ taglib uri="/WEB-INF/struts-bean.tld" prefix="bean" %>
<%@ taglib uri="/WEB-INF/struts-html.tld" prefix="html" %>
<html:html locale="true">
<head>
<title><bean:message key="logon.title"/></title>
<html:base/>
</head>
<body bgcolor="white">
<html:errors/>
<html:form action="/meter">
<table border="0" width="100%">
<tr>
<th align="right">
<bean:message key="prompt.host"/>
</th>
<td align="left">
<html:text property="host" size="16" maxlength="16"/>
</td>
</tr>
<tr>
<th align="right">
<bean:message key="prompt.port"/>
</th>
<td align="left">
<html:text property="port" size="6" maxlength="6"/>
</td>
</tr>
<tr>
<td align="right">
<html:submit property="add" value="Add"/>
</td>
<td align="left">
<html:submit property="remove" value="Remove"/>
</td>
</tr>
<tr>
<td align="right">
<html:select property="selectedHost" size="10">
<html:options property="list"/>
</html:select>
</td>
</tr>
</table>
</html:form>
</body>
</html:html>
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-------------------------------------------
package rwebstruts;
import javax.servlet.http.HttpServletRequest;
import java.util.*;
import org.apache.struts.action.ActionError;
import org.apache.struts.action.ActionErrors;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionMapping;
public final class MeterForm extends ActionForm {
private String host = null;
private String port = null;
private ArrayList list;
private String selectedHost = null;
public MeterForm() {
list = new ArrayList();
ConfProp props = new ConfProp();
Vector v = props.getMeterHosts();
for (int i=0; i<v.size(); i++)
list.add(v.elementAt(i));
setList(list);
}
public String getHost() {
return (this.host);
}
public void setHost(String host) {
this.host = host;
}
public String getPort() {
return (this.port);
}
public void setPort(String port) {
this.port = port;
}
public ArrayList getList() {
return list;
}
public void setList(ArrayList list) {
this.list = list;
}
public String getSelectedHost() {
return selectedHost;
}
public void setSelectedHost(String selectedHost) {
this.selectedHost = selectedHost;
}
public void reset(ActionMapping mapping, HttpServletRequest request) {
this.port = null;
this.host = null;
this.list = null;
}
public ActionErrors validate(ActionMapping mapping,
HttpServletRequest request) {
ActionErrors errors = new ActionErrors();
if (request.getParameter("add") != null) {
if (!validatePort(port)) {
errors.add("port", new
ActionError("error.port.invalid"));
}
}
return errors;
}
public boolean validatePort(String inPort) {
boolean valid = true;
try {
int value = Integer.parseInt(inPort);
if (value > 65535 || value < 1) valid = false;
} catch (NumberFormatException nfe) {
valid = false;
}
return valid;
}
}
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----------------------------------------------
package rwebstruts;
import java.io.IOException;
import java.util.*;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpServletResponse;
import org.apache.struts.action.Action;
import org.apache.struts.action.ActionError;
import org.apache.struts.action.ActionErrors;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.action.ActionServlet;
import org.apache.struts.util.MessageResources;
public final class MeterAction extends Action {
ConfProp props = null;
public MeterAction() {
super();
props = new ConfProp();
}
public ActionForward perform(ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response)
throws IOException, ServletException {
MeterForm mfrm;
if (form==null)
mfrm = new MeterForm();
else
mfrm = (MeterForm)form;
String action = request.getParameter("add");
if (action != null) {
String meterPort = mfrm.getPort().trim();
String newHost;
// the port is optional
if (meterPort.equals(""))
newHost = mfrm.getHost().trim();
else {
newHost = mfrm.getHost().trim() + ":" + meterPort;
}
newHost = newHost.toLowerCase();
boolean found = false;
Vector mMeterHosts = props.getMeterHosts();
for (int i=0; i<mMeterHosts.size(); i++)
if
(((String)mMeterHosts.elementAt(i)).equals(newHost)) {
found = true;
}
if (!found) {
props.addMeterHost(newHost);
mfrm.setHost("");
mfrm.setPort("80");
}
}
action = request.getParameter("remove");
if (action != null) {
String goneHost = mfrm.getSelectedHost();
props.removeMeterHost(goneHost);
}
// populate text area
ArrayList al = new ArrayList();
Vector v = props.getMeterHosts();
for (int i=0; i<v.size(); i++)
al.add(v.elementAt(i));
mfrm.setList(al);
return (mapping.findForward("meter"));
}
}
