Enum

• https://www.mkyong.com/java/java-enum-example/

public enum UserStatus {
    PENDING,
    ACTIVE,
    INACTIVE,
    DELETED;
}

System.out.println(UserStatus.ACTIVE);    // ACTIVE

public enum WhoisRIR {
    ARIN("whois.arin.net"),
    RIPE("whois.ripe.net"),
    APNIC("whois.apnic.net"),
    AFRINIC("whois.afrinic.net"),
    LACNIC("whois.lacnic.net"),
    JPNIC("whois.nic.ad.jp"),
    KRNIC("whois.nic.or.kr"),
    CNNIC("ipwhois.cnnic.cn"),
    UNKNOWN("");

    private String url;

    WhoisRIR(String url) {
        this.url = url;
    }

    public String url() {
        return url;
    }
}

        System.out.println(WhoisRIR.ARIN.url());      //whois.arin.net