Fischmaster3001 Fischmaster3001 - 5 months ago 50
Java Question

c:forEach with Arraylist form:checkbox

I have this Expeption and dont know how to solve it...

I have an Boolean list witch I want to fill in a JSP, the names of the checkbox are in another String List, If there are 3 Strings in the List there should be 3 Checkboxes, if 4 Strings, then 4 and so on

Here is my JSP

<form:form action="/SpringMVC/dbChanges/form" commandName="index" method="POST">
<div>
<h2>neu anlegen:</h2>
<table>
<tr><td>Name:&nbsp;<form:input path="name" style="float: right"/></td><td><div class="errors"><form:errors path="name"/></div></td></tr>
<tr><td>Datum:&nbsp;<form:input path="date" style="float: right"/></td><td><div class="errors"><form:errors path="date"/></div></td></tr>
<tr><td>Nummer:&nbsp;<form:input path="number" style="float: right"/></td><td><div class="errors"><form:errors path="number"/></div></td></tr>
<c:forEach var="systemListEntry" items="${systemList}" varStatus="status">
<tr><td>${systemListEntry.name}: <form:checkbox path="system[${status.index}]" style="float: right"/></td></tr>
</c:forEach>
</table>
<input type="submit" value="Speichern" />
</div>
</form:form>


Here is the Method in my Controller:

@Controller
@RequestMapping("/dbChanges")
@SessionAttributes("changes")
public class DbChangesControllerImpl implements DbChangeController {

private DbChangeService dbChangeService;
private DbChangeValidator validator;

@Autowired
public DbChangesControllerImpl(final DbChangeValidator pValidator,
final DbChangeService pDbChangeService) {
validator = pValidator;
dbChangeService = pDbChangeService;
}

// Changes //

@Override
@RequestMapping(value = "index.html", method = RequestMethod.GET)
public ModelAndView getChanges() {

final List<DbChange> list = dbChangeService.getDbEntrys();

final ModelAndView model = new ModelAndView("index", "index",
new DbChange());
model.addObject("dbChanges", list);
model.addObject("systemList", dbChangeService.getSystems());

model.addObject("year",
java.util.Calendar.getInstance().get(java.util.Calendar.YEAR));

return model;
}
...


dbChangeService.getSystems() returns a List of FdcSystems:

public class FdcSystem {
private String oid;
private String name;

public String getName() {
return name;
}

public void setName(final String pName) {
name = pName;
}

public String getOid() {
return oid;
}
}


and my dbChange Object which is bound to "index" is here:

package com.bla.dbchanges;

import java.util.ArrayList;
import java.util.List;

/**
*
* @author Fabio Stuber
*
*/
// TODO: Impl machen
public class DbChange {
private String name;
private String date;
private int number;
private List<Boolean> systems;

private String oid;

/**
* Konstruktor ohne Id für die Tests
*/
public DbChange(final String pName, final String pDate, final int pNumber) {
name = pName;
date = pDate;
number = pNumber;
}

public DbChange(final String pOid, final String pName, final String pDate, final int pNumber) {
oid = pOid;
name = pName;
date = pDate;
number = pNumber;
}

/**
* default Konstruktor, vom JSP benötigt
*/
public DbChange() {
systems = new ArrayList<Boolean>();
}

public String getName() {
return name;
}

public void setName(final String pName) {
name = pName;
}

public String getDate() {
return date;
}

public void setDate(final String pDate) {
date = pDate;
}

public int getNumber() {
return number;
}

public void setNumber(final int pNumber) {
number = pNumber;
}

public String getOid() {
return oid;
}

public void setOid(final String pOid) {
oid = pOid;
}

public List<Boolean> getSystems() {
return systems;
}

public void setSystems(final List<Boolean> pSystems) {
systems = pSystems;
}

public void addSystem(final Boolean system) {
systems.add(system);
}

}


dbChangesServiceImpl

package com.bla.dbchanges;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.springframework.beans.factory.annotation.Autowired;

import com.bla.dbchanges.context.DbChangeFactory;
import com.bla.dbchanges.model.FdcDbchange;
import com.bla.dbchanges.model.FdcSystem;

public class DbChangeServiceImpl implements DbChangeService {
private final DbChangeDataStoreManager manager;
private final DbChangeFactory factory;

@Autowired
public DbChangeServiceImpl(final DbChangeDataStoreManager pNewManager,
final DbChangeFactory pFactory) {
manager = pNewManager;
factory = pFactory;
}

private Date convertStringToDate(final String date) {
Date parsedDate = new Date();

try {
parsedDate = new SimpleDateFormat("dd.MM.yyyy").parse(date);
} catch (final ParseException e) {
e.printStackTrace();
}

return parsedDate;
}

@Override
public List<DbChange> getDbEntrys() {
final List<DbChange> list = new ArrayList<DbChange>();

for (final FdcDbchange fdcChange : manager.getAllChanges()) {
list.add(factory.createDbChange(fdcChange));
}

return list;
}

@Override
public DbChange getSingleChange(final String pOid) {
final FdcDbchange change = manager.getSingleChange(pOid);

return factory.createDbChange(change);
}

// TODO: Error, er will statt auf meinen schon vorhandenen Eintrag
// zuzugreiffen, einen neuen erstellen mit der gleichen OID
@Override
public void saveChange(final DbChange pChange) {
final FdcDbchange change = factory.createFdcDbchange();
final Set<FdcSystem> systems = new HashSet<FdcSystem>();
final List<FdcSystem> allSystems = manager.getAllSystems();

// TODO: evtl Chain sobald error gefixt ist
if (pChange.getTwa()) {
systems.add(allSystems.get(0));
}
if (pChange.getIwa()) {
systems.add(allSystems.get(1));
}
if (pChange.getPwa()) {
systems.add(allSystems.get(2));
}

change.setChangeDate(convertStringToDate(pChange.getDate()));
change.setChangeName(pChange.getName());
change.setChangeNumber(pChange.getNumber());
change.setSystems(systems);

manager.saveChange(change);
}

@Override
public void delete(final String pOid) {
final FdcDbchange changeToDelete = manager.getSingleChange(pOid);

manager.deleteChange(changeToDelete);
}

@Override
public void editChange(final DbChange pNewChange) {
final FdcDbchange changeToEdit = manager.getSingleChange(pNewChange
.getOid());
final List<FdcSystem> allSystems = manager.getAllSystems();
final Set<FdcSystem> systems = new HashSet<FdcSystem>();

// TODO: hier die selbe Chain
if (pNewChange.getTwa()) {
systems.add(allSystems.get(0));
}
if (pNewChange.getIwa()) {
systems.add(allSystems.get(1));
}
if (pNewChange.getPwa()) {
systems.add(allSystems.get(2));
}

changeToEdit.setSystems(systems);

manager.editChange(changeToEdit);
}

@Override
public List<FdcSystem> getSystems() {
final List<String> systems = new ArrayList<String>();
// for (final FdcSystem system : manager.getAllSystems()) {
// systems.add(system.getName());
// }

return manager.getAllSystems();
}


}

finally, my Exception:


SCHWERWIEGEND: Invalid property 'systems[0]' of bean class [com.bla.dbchanges.DbChange]: Illegal attempt to get property 'systems' threw exception; nested exception is org.springframework.beans.NullValueInNestedPathException: Invalid property 'systems' of bean class [com.bla.dbchanges.DbChange]: Could not instantiate property type [java.lang.Boolean] to auto-grow nested property path: java.lang.InstantiationException: java.lang.Boolean
org.springframework.beans.InvalidPropertyException: Invalid property 'systems[0]' of bean class [com.bla.dbchanges.DbChange]: Illegal attempt to get property 'systems' threw exception; nested exception is org.springframework.beans.NullValueInNestedPathException: Invalid property 'systems' of bean class [com.bla.dbchanges.DbChange]: Could not instantiate property type [java.lang.Boolean] to auto-grow nested property path: java.lang.InstantiationException: java.lang.Boolean
at org.springframework.beans.BeanWrapperImpl.getPropertyValue(BeanWrapperImpl.java:827)
at org.springframework.beans.BeanWrapperImpl.getPropertyValue(BeanWrapperImpl.java:699)
at org.springframework.validation.AbstractPropertyBindingResult.getActualFieldValue(AbstractPropertyBindingResult.java:99)
at org.springframework.validation.AbstractBindingResult.getFieldValue(AbstractBindingResult.java:218)
at org.springframework.web.servlet.support.BindStatus.(BindStatus.java:120)
at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.getBindStatus(AbstractDataBoundFormElementTag.java:179)
at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.getPropertyPath(AbstractDataBoundFormElementTag.java:199)
at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.getName(AbstractDataBoundFormElementTag.java:165)
at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.autogenerateId(AbstractDataBoundFormElementTag.java:152)
at org.springframework.web.servlet.tags.form.AbstractCheckedElementTag.autogenerateId(AbstractCheckedElementTag.java:81)
at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.resolveId(AbstractDataBoundFormElementTag.java:143)
at org.springframework.web.servlet.tags.form.AbstractSingleCheckedElementTag.writeTagContent(AbstractSingleCheckedElementTag.java:83)
at org.springframework.web.servlet.tags.form.CheckboxTag.writeTagContent(CheckboxTag.java:53)
at org.springframework.web.servlet.tags.form.AbstractFormTag.doStartTagInternal(AbstractFormTag.java:103)
at org.springframework.web.servlet.tags.RequestContextAwareTag.doStartTag(RequestContextAwareTag.java:80)
at org.apache.jsp.WEB_002dINF.pages.index_jsp._jspx_meth_form_005fcheckbox_005f0(index_jsp.java:851)
at org.apache.jsp.WEB_002dINF.pages.index_jsp._jspx_meth_c_005fforEach_005f3(index_jsp.java:814)
at org.apache.jsp.WEB_002dINF.pages.index_jsp._jspService(index_jsp.java:242)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:748)
at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:486)
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:411)
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:338)
at org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:238)
at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:264)
at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1208)
at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:992)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:939)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:920)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:816)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:620)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:801)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1040)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:315)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.springframework.beans.NullValueInNestedPathException: Invalid property 'systems' of bean class [com.bla.dbchanges.DbChange]: Could not instantiate property type [java.lang.Boolean] to auto-grow nested property path: java.lang.InstantiationException: java.lang.Boolean
at org.springframework.beans.BeanWrapperImpl.newValue(BeanWrapperImpl.java:633)
at org.springframework.beans.BeanWrapperImpl.growCollectionIfNecessary(BeanWrapperImpl.java:865)
at org.springframework.beans.BeanWrapperImpl.getPropertyValue(BeanWrapperImpl.java:770)
... 56 more


can anyone help me with this Problem?

Answer

Found a Solution, changed the List to a Set in DbChanges.java:

private Set<String> systems;

and changed the JSP to:

<c:forEach var="systemListEntry" items="${systemList}">
    <tr><td>${systemListEntry.name}: <form:checkbox path="systems" value="${systemListEntry.name}" style="float: right"/></td></tr>
</c:forEach>