Bukkit

import java.util.List;
import java.util.Random;
import org.bukkit.Bukkit;
import org.bukkit.Material;
import org.bukkit.block.BlockState;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.block.BlockFormEvent;
import org.bukkit.plugin.java.JavaPlugin;

public final class SnowCarpet extends JavaPlugin implements Listener{
    
    public Random randomGenerator = new Random();
    List<Byte> list;
    
    @Override
    public void onEnable(){
        saveDefaultConfig();
        list = getConfig().getByteList("config.Types"); 
        Bukkit.getServer().getPluginManager().registerEvents(this, this);
    }
    
    @EventHandler
    public void onSnowForm(BlockFormEvent event) {
        BlockState newstate = event.getNewState();
        
	if(newstate.getType() == Material.SNOW) {
            int index = randomGenerator.nextInt(list.size());
            byte data = list.get(index);

            newstate.setType(Material.CARPET);          
            newstate.setRawData(data);
        }
    }
}