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Static instance variables in classes with C#

I am trying to teach myself C#. From the book I am using, I created a Color class and a Ball class. Here is the pertinent code:

public class Color

public int Red;
public int Blue;
public int Green;
public int Alpha;

public Color(int red, int blue, int green, int alpha)

this.Red = red;
this.Blue = blue;
this.Green = green;
this.Alpha = alpha;




This creates the Color class and allows me to assign values to the standard RGB color spectrum we are used to using the Color constructor.

Then I have a method called GetRed(), also within the Color class, which returns the value I set for Red when I create the color in the constructor.

public int GetRed()

return Red;



Finally, I have another class called Ball, where I declare an instance variable color1 to get the Red value from the Color class.

class Ball

public int color1 = Color.GetRed();



The error I get with the color1 declaration in the Ball class is An object reference is required for the non-static field, method, or property "Color.GetRed()".
The fix that Visual Studio suggested was to reference the namespace and the class in the variable declaration, so in my case,public int color1 = Hello_World.Color.GetRed()
and to make the color variables I created in my Color class and the GetRed() method static. This fixes my problem, but I'm wondering if there is another way to fix this, where I don't have to make the variables or the method static. I'm sorry if I didn't explain this very well. I'm just starting out in C#, so if you need clarification, please tell me in a response. Thanks.

An object reference is required for the non-static field, method, or property "Color.GetRed()"

public int color1 = Hello_World.Color.GetRed()

Color

GetRed()

Color.GetRed()

2 Answers
2

public int color1 = Color.GetRed(); <- accessing static method from class Color.

public int color1 = new Color().GetRed(); <- accessing instance method from instance of class Color.

or

public class Ball

private Color _color;

public Ball(Color color)

_color = color;


public int GetColorRedValue()

return _color.GetRed();




and

var color = new Color();
var ball = new Ball(color);

Console.WriteLine(ball.GetColorRedValue()); <- print red color value


You should really create a MCVE. Without one we are left guessing. So I guess this is what your books wants you to do:

class Color

// ...


class Ball

Color SurfaceColor = new Color(/*...*/);



Well, heck, why not, let's go the extra mile. Here is how I would implement the Color - Ball models:

Color

Ball

public static class Colors

public static readonly Color Red = new Color(255, 0, 0);
public static readonly Color Green = new Color(0, 255, 0);
public static readonly Color Blue = new Color(0, 0, 255);

public static readonly Color White = new Color(255, 255, 255);
public static readonly Color Black = new Color(0, 0, 0);


public class Color

public int R;
public int G;
public int B;

public Color() : this(Colors.Black)

public Color(Color other) : this(other.R, other.G, other.B)

public Color(int red, int green, int blue)

R = red;
G = blue;
B = blue;



public class Ball

public Color SurfaceColor get; private set;

public Ball(Color surfaceColor)

SurfaceColor = surfaceColor;



public class Program

public static void Main()

Ball blueBall /* huh */ = new Ball(Colors.Blue);
Ball redBall = new Ball(Colors.Red);
Ball maroonBall = new Ball(new Color(128, 0, 0));




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