Welt.java

import greenfoot.*;  // (World, Actor, GreenfootImage, Greenfoot and MouseInfo)
import java.util.List;
/**
 * Write a description of class Welt here.
 * 
 * @author (your name) 
 * @version (a version number or a date)
 */
public class Welt extends World
{
    public static final int WIDTH = 1400;
    public static final int HEIGHT = 630;
    public static final int CELL = 1;

    private Scroller scroller = null;
    /**
     * Constructor for objects of class Welt.
     * 
     */
    public Welt()
    {    
        // Create a new world with 600x400 cells with a cell size of 1x1 pixels.
        super(WIDTH, HEIGHT, CELL, true); 
        scroller = new Scroller(this, new GreenfootImage("World.png"));
        prepare();
    }

    public void act() {
        scroll();
        spawnCoronaVirus();
    }
    
    public void spawnCoronaVirus(){
        if(Greenfoot.getRandomNumber(1000)<10)
        {
            List<CoronaVirus> allVirus = getObjects(CoronaVirus.class);
            if(allVirus.size() < 10){
                int width = WIDTH-10;
                int height = Greenfoot.getRandomNumber(HEIGHT-10);
                this.addObject(new CoronaVirus(),width, height);  
            }
        }
    }
    
    
    
    
    
    
    
    int speed = 1;
    private void scroll() {
        scroller.scroll(speed,0);
    }

    /**
     * Prepare the world for the start of the program.
     * That is: create the initial objects and add them to the world.
     */
    private void prepare()
    {
        Player player = new Player();
        addObject(player,137,398);
    }
}