VisualForce Page to Display Number of Opportunities for an Account based on StageName Using Map in Pageblock Table

Page:

<apex:page StandardController="Account" extensions="OppCountInAccountController">

<apex:form >

<apex:pageBlock mode="edit">

<apex:pageBlockSection title="Account Details" >

<apex:outputText value="{!Account.name}"></apex:outputText>

</apex:pageBlockSection>

<apex:pageBlockSection title="Opportunity Details">

<apex:pageBlockTable value="{!listStrings}" var="stage"  >

<apex:column headerValue="Stage" value="{!Stage}" />

<apex:column headerValue="Count" value="{!omaps[stage]}" />

</apex:pageBlockTable> 

</apex:pageBlockSection>

</apex:pageBlock>

</apex:form>

</apex:page>

Controller:

public class OppCountInAccountController {

    

    public list<opportunity> listOpps {get;set;} 

    public set<String> Stageslist {get;set;} 

    Public list<Integer> Countlist {get;set;}

    Public List<String> listStrings {get;set;}

    Public Map<String,Integer> omaps {get;set;}

    

    public OppCountInAccountController(ApexPages.StandardController controller) {

        listOpps= [select id,Name,StageName,accountid from Opportunity where accountid=:apexpages.currentpage().getparameters().get('id')];

        Stageslist = new set<String>();

        for(Opportunity opp : listOpps){

            Stageslist.add(opp.stageName);

        }

        listStrings  = new List<String>(Stageslist);

        

        Countlist =new list<Integer>();

        omaps = new Map<String,Integer>();

        for(Integer i=0;i<listStrings.size();i++){

             Integer Num  = [select Count() from Opportunity where accountid=:apexpages.currentpage().getparameters().get('id') And stageName=:listStrings[i]];

             Countlist.add(Num);

             omaps.put(listStrings[i],Num);

         }

        

     }    

}

Note: This Page will work only if you pass an Account id to the page like this,

https://Test-Org-dev-ed--c.ap2.visual.force.com/apex/OppCountInAccount?id=00128000011VoTr