Salesforce code for Mass Update from List View

 Sample code for Opportunity

List view  Button Code

{!REQUIRESCRIPT("/soap/ajax/9.0/connection.js")}

var records = {!GETRECORDIDS( $ObjectType.Opportunity)};

if (records[0] == null ) {

    alert("Please select at least one record.")

} else {

    window.location = '/apex/OpportunityChangeStatus?Id=' + records;

}

Page

<apex:page standardController="Opportunity" extensions="OpportunityChangeStatus" recordSetVar="opp">

    <apex:form >

    <apex:pageBlock >

        <apex:pageBlockButtons >

            <apex:commandButton value="Save" action="{!save}"/>

            <apex:commandButton value="cancel" action="{!cancel}"/>

        </apex:pageBlockButtons>

        <apex:pageBlockSection >

            <apex:pageBlockSectionItem >

                <apex:outputLabel > Select a stage:</apex:outputLabel>

                <apex:inputField value="{!oppRec.StageName}"/>

            </apex:pageBlockSectionItem>    

        </apex:pageBlockSection>

    </apex:pageBlock>

    </apex:form>

</apex:page>

Controller

public class OpportunityChangeStatus {

    

    public Opportunity oppRec{get;set;}

    List<Opportunity> oppList = new List<Opportunity>();

    List<String> oppIdList = new List<String>();

    List<Opportunity> updatedOppList = new List<Opportunity>();

    

    public OpportunityChangeStatus(ApexPages.StandardController controller) {

        

    }

    

    private ApexPages.StandardSetController standardController;

    public OpportunityChangeStatus(ApexPages.StandardSetController standardController){

        oppRec = new Opportunity();        

        String oppId = ApexPages.currentPage().getParameters().get('id');

        oppIdList = oppId.split(',');       

    }

    public Pagereference save(){    

        

        for(String oppId : oppIdList){

            Opportunity opp = new Opportunity();

            opp.Id = oppId;

            opp.StageName = oppRec.StageName;

            updatedOppList.add(opp);

        }        

        if(updatedOppList.size() > 0){

            update updatedOppList;

        }        

        return new PageReference('/006');

    }

}