Question

Consider the following code

public class ColorScheme {

    public static final int     DARK_BLACK  = 0,
                                WHITE       = 1;

    private int Scheme;

    public ColorScheme() {
        this.Scheme     =   DARK_BLACK;
    }

    public ColorScheme(int SchemeType) {
        this.Scheme     =   SchemeType;
    }
}

I want the argument to the constructor ColorScheme(int SchemeType) to be restricted to one of the static final int – DARK_BLACK or WHITE or other constant I may define.

For Ex: When someone instantiates the ColorScheme class, he can use

 ColorScheme CS  = new ColorScheme(DARK_BLACK);

while

 ColorScheme CS  = new ColorScheme(5); //or any other non-defined constant

should return an error.

Answer 1

Enum is the way to go:

public class ColorScheme {

    public enum Color {DARK_BLACK,
                       WHITE}

    private Color Scheme;

    public ColorScheme() {
        this.Scheme     =   Color.DARK_BLACK;
    }

    public ColorScheme(Color SchemeType) {
        this.Scheme     =   SchemeType;
    }
}