Country and State picklist in apex

Question

I want to check if state exists or not with a country in State and Country Picklist feature supported by Salesforce. I want to do this in Apex. How can I do this?

Answer 1

Get the list of countries and states as described here

country code - country name

Schema.DescribeFieldResult fieldResult = 
User.Countrycode.getDescribe();
List<Schema.PicklistEntry> ple = fieldResult.getPicklistValues();
System.debug('Picklist::'+ple);
for( Schema.PicklistEntry f : ple){
System.debug(f.getLabel() +'::'+ f.getValue());
}

state code - state name

Schema.DescribeFieldResult fieldResult = User.statecode.getDescribe();
List<Schema.PicklistEntry> ple = fieldResult.getPicklistValues();
System.debug('Picklist::'+ple);
for( Schema.PicklistEntry f : ple){
System.debug(f.getLabel() +'::'+ f.getValue());
}

The problem is that we don't know which state belongs to which country. That is not as easy to solve, but some solutions are available here

Answer 2

Here is a similar working example as below. The 2nd pick-list value is selected based on the first pick-list through Apex. You can add your Apex logic inside spin() method. Hope this will helps.

VF Page

<apex:page controller="loadingSpinnerCtrl">
    <apex:form id="form">
        <apex:selectList id="selected_list" value="{!dropdown1}" required="false" size="1">
            <apex:selectOption itemvalue="None" itemLabel="--None--"/>
            <apex:selectOption itemvalue="1" itemLabel="First"/>
            <apex:selectOption itemvalue="2" itemLabel="Second"/>
            <apex:actionSupport event="onchange" reRender="form" action="{!spin}" status="status"/>
        </apex:selectList>
        <apex:actionStatus id="status">
            <apex:facet name="start">
                <div>Loading Please wait........</div>
            </apex:facet>
        </apex:actionStatus>
        <apex:selectList id="dropdown2"  required="false" size="1">
            <apex:selectOption itemvalue="None" itemLabel="--None--"/>
            <apex:selectOptions value="{!items}" />
        </apex:selectList>        
    </apex:form>
</apex:page>

Controller

public class loadingSpinnerCtrl {
    public String dropdown1{get; set;}
    public List<SelectOption> options;
    public void spin() {
        if(dropdown1 == '1'){
            options = new List<SelectOption>();
            options.add(new SelectOption('1','Value 1'));
            options.add(new SelectOption('2','Value 2'));
            options.add(new SelectOption('3','Value 3'));

        }else if(dropdown1 == '2'){
            options = new List<SelectOption>();
            options.add(new SelectOption('1','Case 1'));
            options.add(new SelectOption('2','case 2'));
            options.add(new SelectOption('3','case 3'));

        }    
        long now = datetime.now().gettime();
        while(datetime.now().gettime()-now<5000); // Busy loop for 5000 ms
    }
    public List<SelectOption> getItems() {
        return options;
    }    
}