Thread: How to use an ArrayList here?

Hey guys. I wanted to see if someone could help me here. I have the following piece of code that which displays one asteroid on the screen.

// draw asteroid
		if(!status.isNewAsteroid())
		{
			// draw the asteroid until it reaches the bottom of the screen
			if(asteroid.getY() + asteroid.getSpeed() < this.getHeight())
			{
				asteroid.translate(0, asteroid.getSpeed());
 
				// Displays one asteroid on the screen:
				graphicsMan.drawAsteroid(asteroid, g2d, this);
			}
			else
			{
				asteroid.setLocation(rand.nextInt(getWidth() - asteroid.width), 0);
			}
		}

Image of game running with only one asteroid on the screen:

http://i1226.photobucket.com/albums/...dSpaceHelp.jpg

I want to draw more than one asteroid on the screen at the same time. How do I do this? Do I use an Array List? I think I have to use an Enhanced For loop but I am not too sure.

P.S. The new asteroid obviously can't be just a modification of the current asteroid with modified x and y coordinates. It has to be a brand new asteroid of its own of a class Asteroid which I also have and it has to behave differently from the current asteroid. That is why I want to solve the problem with an array list.


Thank you all very much.

hi,
i guess you need to have arraylist of asteroid object and asteroid should have some sort of mechanism (may be pseudo random generator for co-ordinates) so that asteroids have same behaviour but different states..

Originally Posted by Raven123

hi,
i guess you need to have arraylist of asteroid object and asteroid should have some sort of mechanism (may be pseudo random generator for co-ordinates) so that asteroids have same behaviour but different states..

You are correct in the sense that the asteroids have a random generator in its class so that it always starts at a different location. This is the constructor of the Asteroid class:

public Asteroid(GameScreen screen)
{
		this.setLocation(rand.nextInt(screen.getWidth() - asteroidWidth),0);
		this.setSize(asteroidWidth, asteroidHeight);
	}

What I try to do is to create one asteroid with the parameter GameScreen and then put it inside an Array or ArrayList using a loop. Like this:

this.asteroid = new Asteroid(screen);
		for(int i = 0; i <= 2; i++)
		{
			Asteroid[] asteroids = new Asteroid[i];
			asteroids[i] = this.asteroid;
		}

I think that this array isn't working because it seems that I am putting the same asteroid inside every element of the array. How do I create an array that fills up with different asteroids and all of them have the parameter GameScreen?

Originally Posted by Norm

A problem is that the variable defined inside the loop: asteroids which goes away when execution leaves the loop.

A list of the steps the code needs to do:
create an array
begin loop
create a new Asteroid
add that new Asteroid to the array
end loop

Do you suggest an array or an array list?

Originally Posted by Norm

An arraylist.

It worked. Thank you very much. I already gave you the rep

Hello, this seems a little related topic for my Q. I am a Java beginner and would like to confirm answer to this -

Quesiton:
CAN WE DO THIS -
if (myClassList instanceof List<MyClass>)

Thanks