Wrapper Class:

Wrapper Class:
A wrapper or container class is a class, a data structure, or an abstract data type whose instances are collections of other objects. In Apex and Visualforce this type of class can be extremely useful.Here is the scenario How can I display a table of records with a check box and then process only the records that are selected?

public class crwrapperClassController {

    //Our collection of the class/wrapper objects cContact 

    public List<cContact> contactList {get; set;}

    //This method uses a simple SOQL query to return a List of Contacts

    public List<cContact> getContacts() {

        if(contactList == null) {

            contactList = new List<cContact>();

            for(Contact c : [select Id, Name, Email, Phone from Contact limit 10]) {

                // As each contact is processed we create a new cContact object and add it to the contactList

                contactList.add(new cContact(c));

            }

        }

        return contactList;

    }

    public PageReference processSelected() {

                //We create a new list of Contacts that we be populated only with Contacts if they are selected

        List<Contact> selectedContacts = new List<Contact>();

        //We will cycle through our list of cContacts and will check to see if the selected property is set to true, if it is we add the Contact to the selectedContacts list

        for(cContact cCon : getContacts()) {

            if(cCon.selected == true) {

                selectedContacts.add(cCon.con);

            }

        }

        // Now we have our list of selected contacts and can perform any type of logic we want, sending emails, updating a field on the Contact, etc

        System.debug('These are the selected Contacts...');

        for(Contact con : selectedContacts) {

            system.debug(con);

        }

        return null;

    }

    // This is our wrapper/container class. A container class is a class, a data structure, or an abstract data type whose instances are collections of other objects. In this example a wrapper class contains both the standard salesforce object Contact and a Boolean value

    public class cContact {

        public Contact con {get; set;}

        public Boolean selected {get; set;}

        //This is the contructor method. When we create a new cContact object we pass a Contact that is set to the con property. We also set the selected value to false

        public cContact(Contact c) {

            con = c;

            selected = false;

        }

    }

}

<apex:page controller="crwrapperClassController">
    <apex:form >
        <apex:pageBlock >
            <apex:pageBlockButtons >
                <apex:commandButton value="Process Selected" action="{!processSelected}" rerender="table"/>
            </apex:pageBlockButtons>
            <!-- In our table we are displaying the cContact records -->
            <apex:pageBlockTable value="{!contacts}" var="c" id="table">
                <apex:column >
                    <!-- This is our selected Boolean property in our wrapper class -->
                    <apex:inputCheckbox value="{!c.selected}"/>
                </apex:column>
                <!-- This is how we access the contact values within our cContact container/wrapper -->
                <apex:column value="{!c.con.Name}" />
                <apex:column value="{!c.con.Email}" />
                <apex:column value="{!c.con.Phone}" />
            </apex:pageBlockTable>
        </apex:pageBlock>
    </apex:form>
</apex:page>
Before Testing enable your debug logs and it looks like this