Page is not re-rendering after adding select list code - salesforce

Question

I am new In salesforce, currently learning a visualforce elements.
I am having a problem in my code that when I insert a SelectList code in my visualForce page then page re-rendering stops working.
Without SelectList page re-rendering works fine.
I have provided a code snippets below. After adding SelectList save method from controller not getting called also contact i am trying to insert is not getting inserted.
Any help is appreciated.
This is my visualforce page.
<apex:page controller="ContactController">
<apex:form >
<apex:pageBlock>
<apex:pageBlockSection >
<apex:inputField value="{!Contact.AccountId}" label="Account Name:"/>
<apex:inputField value="{!Contact.LastName}" label="LastName"/>
<apex:inputField value="{!Contact.phone}" label="Phone"/>
<apex:inputField value="{!Contact.Department}"/>
<apex:inputField value="{!Contact.Designation__c}"/>
</apex:pageBlockSection>
<apex:pageBlockSection id="id3">
<apex:pageBlockSectionItem >
<apex:actionRegion >
<apex:selectList value="{!Contact}" multiselect="true" id="slist1" style="overflow scroll; height : 100px;">
<apex:actionSupport event="onchange" rerender="id1" />
<apex:selectOptions value="{!ContactFields}"></apex:selectOptions>
</apex:selectList><p/>
</apex:actionRegion>
</apex:pageBlockSectionItem>
</apex:pageBlockSection>
<apex:pageBlockSection id="id1">
<apex:pageBlockTable value="{!contactList}" var="c" >
<apex:column headerValue="Last Name">
<apex:outputField value="{!c.Lastname}"/>
</apex:column>
<!-- <apex:column headerValue="Account">
<apex:outputField value="{!c.Account.Name}"/>
</apex:column> -->
</apex:pageBlockTable>
</apex:pageBlockSection>
<apex:pageBlockButtons >
<apex:commandButton value="Save" action="{!save}" reRender="id1"/>
</apex:pageBlockButtons>
</apex:pageBlock>
</apex:form>
</apex:page>
This is my controller.
public class ContactController {
public Account account { get; private set; }
public Contact contact { get; set; }
public List<Contact> contactList{get {return ([SELECT LastName,Account.Name FROM Contact where Account.Id = :ApexPages.currentPage().getParameters().get('id') order by createdDate DESC limit 5]);} set;}
public Id id;
Map<String, Schema.SobjectField> Contactfields{ get; set;}
List<SelectOption> lstContactFields{get;set;}
public ContactController() {
contact=new Contact();
id = ApexPages.currentPage().getParameters().get('id');
contact.AccountId=id;
Contactfields = Schema.SobjectType.Contact.fields.getMap();
}
public List<SelectOption> getContactFields(){
if(lstContactFields==null){
lstContactFields=new List<SelectOption>();
}
for(Schema.SObjectField s:Contactfields.values()){
Schema.DescribeFieldResult fieldResult = s.getDescribe();
lstContactFields.add(new SelectOption(String.valueof(fieldResult.getName()),String.valueof(fieldResult.getLabel())));
// lstContactFields.add(Contactfields.get(s).getDescribe().getLabel());
//lstContactFields.add(String.valueOf(s));
}
return lstContactFields;
}
public PageReference save() {
try {
System.debug('save method');
upsert contact;
contact.Id=null;
return null;
} catch(System.DMLException e) {
ApexPages.addMessages(e);
return null;
}
// After successful Save, navigate to the default view page
// PageReference pg = new PageReference(System.currentPageReference().getURL());
// pg.setRedirect(true);
// return pg;
}
}

Answer 1

Your value bindings on these components aren't set up correctly.
<apex:selectList value="{!Contact}" multiselect="true" id="slist1" style="overflow scroll; height : 100px;">
An <apex:selectList> needs to be bound to a String or a List<String> (only for multiselect=true). Here, you've bound it to an sObject variable.
The fact that you've named your sObject variable the same as its class, Contact, is highly likely to cause further problems. Apex isn't case-sensitive, so contact and Contact are the same identifier. In general, you should not reuse reserved words or system class names as variable names, which you do again with id.
<apex:selectOptions value="{!ContactFields}"></apex:selectOptions>
<apex:selectOptions> has to have its value bound to a List<SelectOptions>. You've declared a property by that name with the wrong type:
Map<String, Schema.SobjectField> Contactfields{ get; set;}
while also implementing a getter method with the right type:
public List<SelectOption> getContactFields(){
Again, this is likely to produce unintuitive behavior, even if it does compile and render.