发生碰撞时如何消失图像？

Question

I have two images that move in a horizontal direction. Whenever there is a collision between the two images, I want them to disappear and that is my problem. Could someone help me how to do that?

By the way, this is my code. You can check it if you like:

private boolean checkCollisions()
{
    for (Sprite r1 : z_sorted_sprites)
    {
        for (Sprite r2 : z_sorted_sprites)
        {
            if (r1 == r2)
            {
                continue;
            }

            RectangleX me = r1.getBounds();
            RectangleX other = r2.getBounds();

            if (me.intersects(other))
            {
                collision = true;

                System.out.println("collision : " + r1.getName() + " with " + r2.getName());

                // disappear(me,other);
            }
            else
            {
                collision = false;
                System.out.println("no collision");
            }
        }

    }
    return collision;
}

Answer 1

Try the following:

In your paint(Graphics g) method, do the following:

if(!checkCollisions()){
   //draw your sprites
   //g.drawImage(...);
}

And in your checkCollisions() method, call repaint when you detect a collision.

if (me.intersects(other))
            {
                collision = true;

                System.out.println("collision : " + r1.getName() + " with " + r2.getName());

                repaint();
            }

Answer 2

Because you're iterating over the same collection twice, I'm pretty sure you have to tackle it by building a list of items to remove, then removing them once all the collisions have been detected.

Like so:

private boolean checkCollisions()
{
    ArrayList<Sprite> toRemove = new ArrayList<Sprite>();

    for (Sprite r1 : z_sorted_sprites)
    {
        for (Sprite r2 : z_sorted_sprites)
        {
            // ...
            if (me.intersects(other))
            {
                // ...
                toRemove.add(r1);
                toRemove.add(r2);
            }
            else
            {
                // ...
            }
        }
    }

    z_sorted_sprites.removeAll(toRemove);

    return collision;
}

Note that when two sprites collide, they each get added to the toRemove list twice. You can prevent this and make your loop more efficient by changing your for loops like so (assuming z_sorted_sprites is a List ):

for (int i = 0; i < z_sorted_sprites.size(); i++)
{
    Sprite r1 = z_sorted_sprites.get(i);
    for (int j = i + 1; j < z_sorted_sprites.size(); j++)
    {
        Sprite r2 = z_sorted_sprites.get(j);
        // ...
    }
}

As an aside, are you sure your return value is returning what you think it is? Currently it will return false unless the last two sprites in the list happen to collide. If you want it to return true if there are any collisions, get rid of the line collision = false; It might be more useful to return a count of the number of collisions, but I leave that to you...