WaterTile

..
public class WaterTile extends Tile {

    private int anim;

    public WaterTile(Sprite sprite) {
        super(sprite);
    }

    public void render(int x, int y, Screen screen) {
        screen.renderTile(x << 4, y << 4, this);
    }

    public void update() {
        if (anim < 1000000)
            anim++;
        else
            anim = 0;

        if(anim % 30 > 20) {
            sprite = Sprite.water_;
        } else {
            sprite = Sprite.water;
        }
    }
}