import greenfoot.*;  // (World, Actor, GreenfootImage, Greenfoot and MouseInfo)

/**
 * Write a description of class world2 here.
 * 
 * @author (your name) 
 * @version (a version number or a date)
 */
public class world2 extends World
{
    int BlockY = 10;
    int BlockX = 6;
    boolean addWall = false;

    private int [] x = {10,11,12,10};   //J piece
    private int [] y = {10,10,10,10,11};//J piece
    boolean Jpiece = false;
    /**
     * Constructor for objects of class world2.
     * 
     */
    public world2()
    {    
        // Create a new world with 600x400 cells with a cell size of 1x1 pixels.
        super(30, 30, 30);  
        prepare();

    }

    public void act()
    {
        Addwall();
        setPaintOrder(Wall.class,block.class);
        addBlock();
    }

    public void Addwall()
    {
        if (!addWall)
        {
            Greenfoot.setSpeed(70);
            Wall wall = new Wall();
            addObject(wall,BlockY,BlockX);
            BlockY++;
            if (BlockY == 20)
            {
                BlockX = BlockX + 1;
                BlockY = 10;
                if (BlockX > 29 && BlockY == 10)  
                {
                    addWall = true;  
                    Greenfoot.setSpeed(50);
                }
            } 
        }
    }

    private void addBlock()
    {
        if (!Jpiece)
        {
            for (int r = 0; r< x.length; r++)
            {
                addObject(new block(), x[r], y[r]);
            }
            
            Jpiece = true;
        }
    }

    /**
     * Prepare the world for the start of the program.
     * That is: create the initial objects and add them to the world.
     */
    private void prepare()
    {

    }
}

import greenfoot.*;  // (World, Actor, GreenfootImage, Greenfoot and MouseInfo)

/**
 * Write a description of class block here.
 * 
 * @author (your name) 
 * @version (a version number or a date)
 */
public class block extends Actor
{
    public block()
    {
        GreenfootImage image = getImage();  
        image.scale(30, 30);
        image.setColor(Color.BLACK);
        setImage(image);
        
    }
    /**
     * Act - do whatever the block wants to do. This method is called whenever
     * the 'Act' or 'Run' button gets pressed in the environment.
     */
    public void act() 
    {
        setLocation(getX(), getY() +1);
        if (isTouching(block.class)) setLocation(getX(), getY()-1);
       
       if (Greenfoot.isKeyDown ("A"))
        {setRotation(90);                       //Move left
        }
    }    
}