Making Walls :)

heres the full code for the rcket (currently its mostly taken fom asteroids because i havnt edited yet) import greenfoot.*; // (World, Actor, GreenfootImage, and Greenfoot) /** * A rocket that can be controlled by the arrowkeys: up, left, right. * The gun is fired by hitting the 'space' key. * * @author Poul Henriksen * @author Michael Kolling */ public class Rocket extends Mover { private int gunReloadTime; // The minimum delay between firing the gun. private int reloadDelayCount; // How long ago we fired the gun the last time. private Vector acceleration; // How fast the rocket is. private int shotsFired; // Number of shots fired. private GreenfootImage rocket = new GreenfootImage("rocket.png"); private GreenfootImage rocketWithThrust = new GreenfootImage("rocketWithThrust.png"); /** * Initilise this rocket. */ public Rocket() { gunReloadTime = 20; reloadDelayCount = 0; acceleration = new Vector(0, 0.05); increaseSpeed(new Vector(13, 0.05)); // initially slowly drifting shotsFired = 0; } /** * Do what a rocket's gotta do. (Which is: mostly flying about, and turning, * accelerating and shooting when the right keys are pressed.) */ public void act() { move(); checkCollision(); checkKeys(); reloadDelayCount++; stopatWall(); } /** * Return the number of shots fired from this rocket. */ public int getShotsFired() { return shotsFired; } /** * Return the approximate current travelling speed of this rocket. */ public int getSpeed() { return (int) (getMovement().getLength() * 10); } /** * Set the time needed for re-loading the rocket's gun. The shorter this time is, * the faster the rocket can fire. The (initial) standard time is 20. */ public void setGunReloadTime(int reloadTime) { gunReloadTime = reloadTime; } /** * Check whether we are colliding with an asteroid. */ private void checkCollision() { Asteroid a = (Asteroid) getOneIntersectingObject(Asteroid.class); if(a != null) { getWorld().addObject(new Explosion(), getX(), getY()); getWorld().removeObject(this); } } /** * Check whether there are any key pressed and react to them. */ private void checkKeys() { ignite(Greenfoot.isKeyDown("w")); if(Greenfoot.isKeyDown("a")) { setRotation(getRotation() - 5); } if(Greenfoot.isKeyDown("d")) { setRotation(getRotation() + 5); } if(Greenfoot.isKeyDown("space")) { fire(); } } /** * Should the rocket be ignited? */ private void ignite(boolean boosterOn) { if(boosterOn) { setImage(rocketWithThrust); acceleration.setDirection(getRotation()); increaseSpeed(acceleration); } else { setImage(rocket); } } /** * Fire a bullet if the gun is ready. */ private void fire() { if(reloadDelayCount >= gunReloadTime) { Bullet b = new Bullet(getMovement().copy(), getRotation()); getWorld().addObject(b, getX(), getY()); b.move(); shotsFired++; reloadDelayCount = 0; } } public boolean canSee(Class clss) { Actor actor = getOneObjectAtOffset(0, 0, clss); return actor != null; } public void stopatWall() { if(canSee(Wall.class)) { acceleration = new Vector(0, 0); increaseSpeed(new Vector(0, 0)); Greenfoot.stop(); } } } Thanks

Well, either try this: import greenfoot.*; /** * A surface for the main actor to gravitate toward. */ public class nameofclass extends Actor { /** * Creates a long platform for the main actor. */ public nameofclass() { GreenfootImage nameofclass = new GreenfootImage("nameofclass.jpg"); GreenfootImage image = new GreenfootImage(1040, nameofclass.getHeight()); int w=nameofclass.getWidth(); for(int offset=0; offset<1040; offset+=w) image.drawImage(nameofclass, offset, 0); setImage(image); } } Or this: import greenfoot.*; /** * An object to act as an obstacle. */ public class nameofclass extends Actor { /** * Creates the object and sizes its image. */ public nameofclass() { getImage().scale(40, 40); } } Hope this helps, one of them should work. TheRoshax

You could change your 'checkCollision' method to include the Wall as follows: If there is a 'setSpeed' method, use it to zero the speed. If not, and you must use 'increaseSpeed', then assuming that you have a method called 'getSpeed' that returns a Vector object, say 'increaseSpeed(-getSpeed())'.

Looks like you might run into either a nullPointerException in your 'fire' method (around line 122 of the Rocket class or an illegalStateException in the 'canSee' method of the Mover class when the rocket hits an asteroid. The rocket is removed from the world when it hits an asteroid, so any intersect checking (or use of 'getX' or 'getY') will fail and any 'getWorld' call will return null. To avoid these possible errors, change your 'act' method in the Rocket class to: