my code wont work

import greenfoot.*;

/**
 * Write a description of class Timer here.
 * 
 * @author (your name) 
 * @version (a version number or a date)
 */
public class Timer extends Actor
{
    /**
     * Act - do whatever the Timer wants to do. This method is called whenever
     * the 'Act' or 'Run' button gets pressed in the environment.
     */
    public void act() 
    {
        // Add your action code here.
    }    
    
    public void Timer()
    {
        getWorld().addObject(new Thirty_Three(), 300, 200);
        Greenfoot.delay(50);
        getWorld().removeObject(Thirty_Three.class);
        getWorld().addObject(new Thirty_Two(), 300, 200);
        Greenfoot.delay(50);
        getWorld().removeObjects(Thirty_Two.class);
        addObject(new Thirty_One(), 300, 200);
    }
}