How do I define constructor in enum type?

In the following example you'll see how to add a constructor to an enum type value. Because an enum is just another class type it can have constructors, fields and methods just like any other classes. Below we define a constructor that accept a string value of color code. Because our enum now have a new constructor declared we have to define the constant named value as RED("FF0000"), ORANGE("FFA500"), etc.

package org.kodejava.example.fundamental;

//
// In Java enumeration expanded beyond just as a named constants. Because enum 
// is a class type we can add methods, fields and constructors to the enum type
// as you can see in the example below.
//
enum Rainbow {
    RED("FF0000"),
    ORANGE("FFA500"),
    YELLOW("FFFF00"),
    GREEN("008000"),
    BLUE("0000FF"),
    INDIGO("4B0082"),
    VIOLET("EE82EE");

    private String colorCode;

    //
    // The constructor of Rainbow enum.
    //
    Rainbow(String colorCode) {
        this.colorCode = colorCode;
    }

    /**
     * Get the hex color code.
     * @return
     */
    public String getColorCode() {
        return colorCode;
    }
}

public class EnumConstructor {
    public static void main(String[] args) {
        
        //
        // To get all values of the Rainbow enum we can call the Rainbow.values() 
        // method which return an array of Rainbow enum values.
        //        
        for (Rainbow color : Rainbow.values()) {
            System.out.println("Color = " + color.getColorCode());
        }
    }
}