Map Scenario

Scenario: 
Create field dependency using vf page

public class MapEaxmple {

    public Map<String, Account>  accMap{set;get;}

    public List<SelectOption> sp{set;get;}

    public Account accs{set;get;}

    public String selected{set;get;}

    public String result{set;get;}

    public MapEaxmple(){

        accMap=new Map<String, Account>();

        sp=new List<SelectOption>();

        Account a1=new Account(name='emilyn', phone='903030');

        Account a2=new Account(name='aabbcc', phone='78576');

        accMap.put('First', a1);

        accMap.put('Sec', a2);

        Set<String> keys=accMap.keySet();

        for(String s:keys){

            SelectOption sop=new SelectOption(s,s);

            sp.add(sop);

        }

    }

    public void data(){

        accs=accMap.get(selected);  

    } 

    }

<apex:page controller="MapEaxmple">

    <apex:form >

               <apex:pageBlock >

               <apex:pageBlockSection >

               <apex:selectList value="{!selected}" size="1">

                              <apex:selectOptions value="{!sp}"  ></apex:selectOptions>

                    <apex:actionSupport event="onchange" action="{!data}" reRender="one" />

                </apex:selectList>

            </apex:pageBlockSection>

            <apex:pageBlockTable value="{!accs}" var="a" id="one">

                <apex:column headerValue="name" value="{!a.name}" />

                <apex:column headerValue="Phone" value="{!a.phone}" />

           

            </apex:pageBlockTable>

           

        </apex:pageBlock>

    </apex:form>

</apex:page>