Pagination using Map not working - salesforce

Question

I am trying to use Map<Question, List<Option>> for Pagination in my Visualforce Page. I have set pageSize to 1. At first it shows only 1 question and its respective options but when I press Next (>) button, it shows previous question as well as next question. That means, it shows 2 questions with their respective options. Then when I press next again, it shows 3 questions with their options.
I want to show only 1 question and its options on each click. On next it should show the next question and on Previous (<) it should show the last question.
This is my Apex Class:
public with sharing class SurveyExtension{
Survey__c survey{get; set;}
List<Survey_Question__c> ques;
public Map<Survey_Question__c, List<SelectOption>> questions= new Map<Survey_Question__c, List<SelectOption>>();
public String answer{get;set;}
public SurveyExtension(ApexPages.StandardController con){
survey = (Survey__c) con.getRecord();
}
public ApexPages.StandardSetController setCon {
get{
if(setCon == null){
setCon = new ApexPages.StandardSetController([select Question__c,Option1__c,Option2__c,Option3__c,Option4__c,Option5__c,Option6__c from Survey_Question__c where Survey__r.id= :survey.id]);
setCon.setPageSize(1);
//noOfRecords = setCon.getResultSize();
}
return setCon;
}set;
}
public Map<Survey_Question__c, List<SelectOption>> getQuestions(){
ques = (List<Survey_Question__c>) setCon.getRecords();
for(Survey_Question__c que: ques){
List<SelectOption> olist = new List<SelectOption>();
olist.add(new SelectOption('a',que.Option1__c));
olist.add(new SelectOption('b',que.Option2__c));
olist.add(new SelectOption('c',que.Option3__c));
olist.add(new SelectOption('d',que.Option4__c));
olist.add(new SelectOption('e',que.Option5__c));
olist.add(new SelectOption('f',que.Option6__c));
questions.put(que, olist);
}
return questions;
}
public void first() {
setCon.first();
}
public void last() {
setCon.last();
}
public void previous() {
setCon.previous();
}
public void next() {
setCon.setPageSize(1);
setCon.next();
}
public Boolean hasNext {
get {
return setCon.getHasNext();
}
set;
}
public Boolean hasPrevious {
get {
return setCon.getHasPrevious();
}
set;
}
}
and this is my Visualforce Page :
<apex:page standardController="Survey__c" extensions="SurveyExtension">
<apex:form >
<apex:pageBlock title="Survey Title" id="queBlock">
<apex:repeat value="{!questions}" var="que">
Question : {!que.Question__c} <br/><br/>
Options :
<apex:repeat value="{!questions[que]}" var="opt">
<apex:selectRadio value="{!answer}">
<apex:selectOptions value="{!opt}" />
</apex:selectRadio>
</apex:repeat>
</apex:repeat>
<apex:panelGrid columns="5">
<apex:commandButton status="fetchStatus" reRender="queBlock" value="|<" action="{!first}" disabled="{!!hasPrevious}" title="First Page"/>
<apex:commandButton status="fetchStatus" reRender="queBlock" value="<" action="{!previous}" disabled="{!!hasPrevious}" title="Previous Page"/>
<apex:commandButton status="fetchStatus" reRender="queBlock" value=">" action="{!next}" disabled="{!!hasNext}" title="Next Page"/>
<apex:commandButton status="fetchStatus" reRender="queBlock" value=">|" action="{!last}" disabled="{!!hasNext}" title="Last Page"/>
<apex:outputPanel style="color:#4AA02C;font-weight:bold">
<apex:actionStatus id="fetchStatus" startText="Fetching..." stopText=""/>
</apex:outputPanel>
</apex:panelGrid>
</apex:pageBlock>
</apex:form>

Answer 1

This is happening because you are not re initializing your map variable "questions" in method getQuestions(). You must add a line in method getQuestions() to re initializing map variable "questions". This will make it empty and only 1 question will be added to it afterwards. See the below corrected code of getQuestions() method -:
public Map<Survey_Question__c, List<SelectOption>> getQuestions(){
//---------You must add this below line---------------------------
questions= new Map<Survey_Question__c, List<SelectOption>>();
ques = (List<Survey_Question__c>) setCon.getRecords();
for(Survey_Question__c que: ques){
List<SelectOption> olist = new List<SelectOption>();
olist.add(new SelectOption('a',que.Option1__c));
olist.add(new SelectOption('b',que.Option2__c));
olist.add(new SelectOption('c',que.Option3__c));
olist.add(new SelectOption('d',que.Option4__c));
olist.add(new SelectOption('e',que.Option5__c));
olist.add(new SelectOption('f',que.Option6__c));
questions.put(que, olist);
}
return questions;
}