Example of an advanced enum

CreditCardType.java

package com.lq;

public enum CreditCardType {
	VISA("111-22-3333") {

		@Override
		public boolean isValid() {
			System.out.println("Validating a " + this.name());
			return false;
		}
	},
	MASTERCARD("0123456789") {
		@Override
		public boolean isValid() {
			System.out.println("Validating a " + this.name());
			return false;
		}
	},
	AMEX("37957893457834") {
		@Override
		public boolean isValid() {
			System.out.println("Validating a " + this.name());
			return false;
		}
	};

	private String number;

	private CreditCardType(String number) {
		this.number = number;
	}

	public abstract boolean isValid(); // write card specific validation
	// LUND's formula
}