Newly loaded sprites not behaving properly in XNA 4.0 - xna

Question

Here is the code for a project im working on, where an enemy moves back and forth at the bottom of the screen.
class enemy1
{
Texture2D texture;
public Vector2 position;
bool isAlive = false;
Random rand;
int whichSide;
public enemy1(Texture2D texture, Vector2 position)
{
this.texture = texture;
this.position = position;
}
public void Update()
{
if (isAlive)
{
if (whichSide == 1)
{
position.X += 4;
if (position.X > 1000 + texture.Width)
isAlive = false;
}
if (whichSide == 2)
{
position.X -= 4;
if (position.X < 0)
isAlive = false;
}
}
else
{
rand = new Random();
whichSide = rand.Next(1, 3);
SetInStartPosition();
}
}
private void SetInStartPosition()
{
isAlive = true;
if (whichSide == 1)
position = new Vector2(0 - texture.Width, 563 - texture.Height);
if (whichSide == 2)
position = new Vector2(1000 + texture.Width, 563 - texture.Height);
}
public void Draw(SpriteBatch spriteBatch)
{
spriteBatch.Draw(texture, position, Color.White);
}
}
Now i want there to be a few enemys going back and forth but they start at differant positions so it looks like there is a few enemys going back and forth at the bottom of the screen. I have managed to draw a few other enemies on the screen, except they do not behave like the first enemy. They just are pictures on a screen not moving anywhere. So now all i have is the hero moving around and one enemy at the bottom of the screen, along with 5 other enemys sitting at the top of the screen doing nothing. How do i easily add a new sprite from a class that has the same behavior, at any time, while not making a billion variables to store them in?

Answer 1

Generally it's a good idea to have similar logic contained within the proper class, so if all Sprites where to do the same thing, then all you would need to do is put your movement code inside a public method and then call that method inside Update().
So, if your Sprite class looks something like this:
public class Sprite
{
private Vector2 Position;
public Sprite(Texture2D texture, Vector2 position)
{
Position = position;
}
//then just add this
public void MoveSprite(int amount)
{
position.X += amount;
}
}
Now, the object name "Sprite" is pretty generic, you will more than likely have many "Sprites" in your game.
So you're going to want to follow good OOP practices and maybe name this specific sprite something different and then have it derive from this class we're looking at right now. (But i'm not going to make design decisions for you)
This was a vague question, but that's my best shot at an answer for you.