Below is the simple code to select Radio button by default in Visualforce page.


Visualforce:


<apex:selectRadio value=”{!searchCategory}” >
    <apex:selectOption itemValue=”Member” itemlabel=”Member”/>
    <apex:selectOption itemValue=”Blog” itemlabel=”Blog”/>
    <apex:selectOption itemValue=”Photo” itemlabel=”Photo”/>
</apex:selectRadio>

Apex:

public class search 
{
………………………………………………….

………………………………………………….
// Constructor of the class
public search()
{
searchCategory = ‘Member’;
}
………………………………………………….

………………………………………………….

}