ContactListener doesn't work [Jbox2D]

Engines, Libraries and Tools
#1

Hi. First, sorry if I post this on the wrong place.
I am developing a platform game with slick and JBox2d, but I can’t get the contactlistener (for collision) work. I create a class that implement ContactListener. When the world class is initialized, call the super class and create a map with tiledmap, and look for all the tiles on the map, for create static bodies for collision, but doesn’t work and I can’t see the problem. Any idea? Thanks

Game.class


		World world = new World(new Vec2(0, Util.GRAVITY));
		world.setContactListener(new Listener(this));

World.class

public class World extends org.jbox2d.dynamics.World {

	public World(Vec2 gravity) {
		this(gravity, 0);
	}

	public World(Vec2 gravity, int lvl) {
		super(gravity);
		try {
			map = new TiledMap(Util._RES + path + maps[lvl]);
		} catch (SlickException e) {
			e.printStackTrace();
		}
		generateMap();
	}

	// Generate box2d bodies for all tiles
	private void generateMap() {
		int layerIndex = map.getLayerIndex("base");
		for (int tileX = 0; tileX < map.getWidth(); tileX++) {
			for (int tileY = 0; tileY < map.getHeight(); tileY++) {
				int tileID = map.getTileId(tileX, tileY, layerIndex);
				String type = map.getTileProperty(tileID, "type", null);
				if (type != null && type.equals("grass")) {
					// Create box2d bodie for this tile
					Vector2 position = tileToWorld(tileX, tileY);
					position.add(map.getTileWidth() / 2,
							map.getTileHeight() / 2);

					Vec2 physicsPosition = toPhysicsVector(position);
					createBoxBody(physicsPosition, map.getTileWidth(),
							map.getTileHeight(), BodyType.STATIC);
				}
			}
		}
	}

	private Body createBoxBody(Vec2 position, float width, float height,
			BodyType type) {
		BodyDef bodyDef = new BodyDef();
		bodyDef.position = position;
		bodyDef.type = type;
		bodyDef.linearDamping = 0.5f;

		FixtureDef fixture = new FixtureDef();
		PolygonShape shape = new PolygonShape();
		shape.setAsBox(width * 0.5f / PTM, height * 0.5f / PTM);
		fixture.shape = shape;

		Body body = createBody(bodyDef);
		body.createFixture(fixture);
		return body;
	}

	private Vec2 toPhysicsVector(Vector2 vector) {
		return new Vec2(vector.getX() / PTM, vector.getY() / PTM);
	}

	public Vector2 tileToWorld(int tileX, int tileY) {
		return new Vector2(MAP_X + map.getTileWidth() * tileX, MAP_Y
				+ map.getTileHeight() * tileY);
	}

	public Vector2 tiledMapToWorld(float x, float y) {
		return new Vector2(MAP_X + x, MAP_Y + y);
	}

}

and Listener.class

public class Listener implements ContactListener {
	
	private Game game;

	public Listener(Game g) {
		this.game = g;
	}

	@Override
	public void beginContact(Contact contact) {
		System.out.println("Collision!!");
	}

	@Override
	public void endContact(Contact contact) { }

	@Override
	public void postSolve(Contact contact, ContactImpulse ci) { }

	@Override
	public void preSolve(Contact contact, Manifold mani) { }

}

PS: I removed some code for make more redeable the post