Can someone explain to me the difference between 2 XNA methods?

Question

I was recently trying to make a boucing ball off the environment walls. I apparently had everything correct, except for one thing, that I corrected stupidly, which made my code work, but I don't understand why.

So I had set the value of a 2d vector's X and Y inside protected override void Update(GameTime gameTime); this vector was what I would add to the object's X and Y so it could move according to whatever logic.

But it didn't work, the fix to this problem was to apparently declare the vector's values inside protected override void LoadContent().

So can anyone explain to me, what is the difference between declaring your variables/constants inside these two methods? And why?

EDIT : Wrong Sourcecode :

  protected override void LoadContent()
    {
        // Create a new SpriteBatch, which can be used to draw textures.
        spriteBatch = new SpriteBatch(GraphicsDevice);

        // Loaded content
}
 protected override void Update(GameTime gameTime)
    {

        // Allows the game to exit
        if (Keyboard.GetState(PlayerIndex.One).IsKeyDown(Keys.Escape))
            this.Exit();

         //Code logic

            movement.X = 5;
            movement.Y = 5;
            birdbox3.X += (int)movement.X; //this variable was declared outside of any local field as a rectangle

            if (birdbox3.X <= 0)
            {

                movement.X = -movement.X;
            }
            else if (birdbox3.Y <=0)
            { movement.Y = - movement.X;
            }
            base.Update(gameTime);
        }

So when I would run this code, the birdbox3 would just stop when the if statement is fulfilled. The correct version would be to cut the

            movement.X = 5;
            movement.Y = 5;

and paste it into LoadContent() instead. The problem is I do not know why.

Answer 1

Assuming "LoadContent" gets called once at startup and "Update" gets called every frame, your issue is probably because the ball's X and Y coordinate got set to 5 every frame in the update method, therefore, it wouldn't be moving around freely...

If it gets called once in the LoadContent method then it does not continually update the X and Y position to be at position X:5 and Y:5.

Setting the position of x and y in the once called "LoadContent" method allows for the movement logic to operate. Setting the position in "Update" would override your movement logic.

:)