Get Selected Record Type Before Insert Using Apex Trigger

Question

How can I display the selected record type name in my vf page even though it is not totally inserted yet?

Note: I am using salesforce's standard record selection.

Someone told me to use before insert in apex trigger, but I am not so used to it. Can anyone show me how to execute this?

Meanwhile, here are my controller and visualforce page:

Controller:

public class TheController {
    private ApexPages.StandardController controller;
    public Object__c obj {get;set;}
    public List<Object__c> objList {get;set;}

    public TheController(ApexPages.StandardController con) {
        controller = con; 
        this.obj = (Object__c)controller.getRecord();   
        Object__c obj = new Object__c();
        List<Object__c> objList = new List<Object__c>();
    }

    public PageReference save() {

        objList = new List<Object__c>();
        Object__c__c obj2 = new Object__c();

        obj2.Field1__c = obj.Field1__c;
        obj2.Field2__c = obj.Field2__c;
        obj2.Field3__c = obj.Field3__c;
        obj2.Field4__c = obj.Field4__c;
        objList.add(obj2);

        if(!objList.isEmpty()) {

            insert objList; 

        }    

        PageReference pg = new PageReference('/' + obj2.Id);
        pg.setRedirect(true);
        return pg;
    }

}

Visualforce Page:

<apex:page standardController="Object__c" extensions="TheController">
    <apex:form >
        <apex:pageBlock >

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

            <apex:pageBlockSection columns="1">
                <apex:inputField value="{!obj.Field1__c}"/>
                <apex:inputField value="{!obj.Field2__c}"/>
                <apex:inputField value="{!obj.Field3__c}"/>
                <apex:inputField value="{!obj.Field4__c}"/>
            </apex:pageBlockSection>

        </apex:pageBlock>
    </apex:form>  
</apex:page>

Answer 1

If you use standard Controller you can just use:

<apex:page standardController="Object__c" >
<apex:form >
    <apex:pageBlock >
        <apex:pageBlockSection >
            <apex:inputField value="{!Object__c.RecordTypeId}" />
        </apex:pageBlockSection>
    </apex:pageBlock>
</apex:form>

Or if you need some logic on selection try this:

<apex:page standardController="Object__c" extensions="TheController">
<apex:form >
    <apex:pageBlock >
        <apex:pageBlockSection >
            <apex:selectList value="{!Object__c.RecordTypeId}" size="1" > 
                <apex:selectOptions value="{!rtypes}"/>
            </apex:selectList>
        </apex:pageBlockSection>
    </apex:pageBlock>
</apex:form>

public class TheController {

public TheController(ApexPages.StandardController controller) {}

public Selectoption[] getRTypes(){
    SelectOption[] options = new Selectoption[]{};
    //change query to filter out some data - as needed
    for(RecordType rt : [SELECT Id, Name FROM RecordType]){
        options.add(new SelectOption(rt.Id, rt.Name));
    }  
    return options ;
}
}