一个标准的JAVA枚举类

一个标准的JAVA枚举类（来源是LMAX公司的一个提供银行的小项目）

/** * Copyright 2013 Marc Wrobel ([e-mail]) * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * *      http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */package fr.marcwrobel.jbanking;/** * The countries having an ISO 3166-1-alpha-2 code. * * <p> * Please be advised that this list is current as of 2013/05/26. Up-to-date list can be found for free on the <a href="http://www.iso.org/iso/home/standards/country_codes.htm"> * International Organization for Standardization website</a>. * </p> * * @author Marc Wrobel * @see <a href="http://www.iso.org/iso/home/standards/country_codes.htm">http://www.iso.org/iso/home/standards/country_codes.htm</a> * @since 1.0 */public enum IsoCountry {    AFGHANISTAN("AF"),    ALAND_ISLANDS("AX"),    ALBANIA("AL"),    ALGERIA("DZ"),    AMERICAN_SAMOA("AS"),    ANDORRA("AD"),    ANGOLA("AO"),    ANGUILLA("AI"),    ANTARCTICA("AQ"),    ANTIGUA_AND_BARBUDA("AG"),    ARGENTINA("AR"),    ARMENIA("AM"),    ARUBA("AW"),    AUSTRALIA("AU"),    AUSTRIA("AT"),    AZERBAIJAN("AZ"),    BAHAMAS("BS"),    BAHRAIN("BH"),    BANGLADESH("BD"),    BARBADOS("BB"),    BELARUS("BY"),    BELGIUM("BE"),    BELIZE("BZ"),    BENIN("BJ"),    BERMUDA("BM"),    BHUTAN("BT"),    BOLIVIA("BO"),    BONAIRE("BQ"),    BOSNIA_AND_HERZEGOVINA("BA"),    BOTSWANA("BW"),    BOUVET_ISLAND("BV"),    BRAZIL("BR"),    BRITISH_INDIAN_OCEAN_TERRITORY("IO"),    BRITISH_VIRGIN_ISLANDS("VG"),    BRUNEI_DARUSSALAM("BN"),    BULGARIA("BG"),    BURKINA_FASO("BF"),    BURUNDI("BI"),    CAMBODIA("KH"),    CAMEROON("CM"),    CANADA("CA"),    CAPE_VERDE("CV"),    CAYMAN_ISLANDS("KY"),    CENTRAL_AFRICAN_REPUBLIC("CF"),    CHAD("TD"),    CHILE("CL"),    CHINA("CN"),    CHRISTMAS_ISLAND("CX"),    COCOS_ISLANDS("CC"),    COLOMBIA("CO"),    COMOROS("KM"),    CONGO("CG"),    COOK_ISLANDS("CK"),    COSTA_RICA("CR"),    COTE_D_IVOIRE("CI"),    CROATIA("HR"),    CUBA("CU"),    CURACAO("CW"),    CYPRUS("CY"),    CZECH_REPUBLIC("CZ"),    DENMARK("DK"),    DJIBOUTI("DJ"),    DOMINICA("DM"),    DOMINICAN_REPUBLIC("DO"),    ECUADOR("EC"),    EGYPT("EG"),    EL_SALVADOR("SV"),    EQUATORIAL_GUINEA("GQ"),    ERITREA("ER"),    ESTONIA("EE"),    ETHIOPIA("ET"),    FALKLAND_ISLANDS("FK"),    FAROE_ISLANDS("FO"),    FIJI("FJ"),    FINLAND("FI"),    FRANCE("FR"),    FRENCH_GUIANA("GF"),    FRENCH_POLYNESIA("PF"),    FRENCH_SOUTHERN_TERRITORIES("TF"),    GABON("GA"),    GAMBIA("GM"),    GEORGIA("GE"),    GERMANY("DE"),    GHANA("GH"),    GIBRALTAR("GI"),    GREECE("GR"),    GREENLAND("GL"),    GRENADA("GD"),    GUADELOUPE("GP"),    GUAM("GU"),    GUATEMALA("GT"),    GUERNSEY("GG"),    GUINEA("GN"),    GUINEA_BISSAU("GW"),    GUYANA("GY"),    HAITI("HT"),    HEARD_ISLAND_AND_MCDONALD_ISLANDS("HM"),    HONDURAS("HN"),    HONG_KONG("HK"),    HUNGARY("HU"),    ICELAND("IS"),    INDIA("IN"),    INDONESIA("ID"),    IRAN("IR"),    IRAQ("IQ"),    IRELAND("IE"),    ISLE_OF_MAN("IM"),    ISRAEL("IL"),    ITALY("IT"),    JAMAICA("JM"),    JAPAN("JP"),    JERSEY("JE"),    JORDAN("JO"),    KAZAKHSTAN("KZ"),    KENYA("KE"),    KIRIBATI("KI"),    KUWAIT("KW"),    KYRGYZSTAN("KG"),    LAO_PEOPLES_DEMOCRATIC_REPUBLIC("LA"),    LATVIA("LV"),    LEBANON("LB"),    LESOTHO("LS"),    LIBERIA("LR"),    LIBYA("LY"),    LIECHTENSTEIN("LI"),    LITHUANIA("LT"),    LUXEMBOURG("LU"),    MACAO("MO"),    MACEDONIA("MK"),    MADAGASCAR("MG"),    MALAWI("MW"),    MALAYSIA("MY"),    MALDIVES("MV"),    MALI("ML"),    MALTA("MT"),    MARSHALL_ISLANDS("MH"),    MARTINIQUE("MQ"),    MAURITANIA("MR"),    MAURITIUS("MU"),    MAYOTTE("YT"),    MEXICO("MX"),    MICRONESIA("FM"),    MOLDOVA("MD"),    MONACO("MC"),    MONGOLIA("MN"),    MONTENEGRO("ME"),    MONTSERRAT("MS"),    MOROCCO("MA"),    MOZAMBIQUE("MZ"),    MYANMAR("MM"),    NAMIBIA("NA"),    NAURU("NR"),    NEPAL("NP"),    NETHERLANDS("NL"),    NEW_CALEDONIA("NC"),    NEW_ZEALAND("NZ"),    NICARAGUA("NI"),    NIGER("NE"),    NIGERIA("NG"),    NIUE("NU"),    NORFOLK_ISLAND("NF"),    NORTHERN_MARIANA_ISLANDS("MP"),    NORTH_KOREA("KP"),    NORWAY("NO"),    OMAN("OM"),    PAKISTAN("PK"),    PALAU("PW"),    PALESTINE("PS"),    PANAMA("PA"),    PAPUA_NEW_GUINEA("PG"),    PARAGUAY("PY"),    PERU("PE"),    PHILIPPINES("PH"),    PITCAIRN("PN"),    POLAND("PL"),    PORTUGAL("PT"),    PUERTO_RICO("PR"),    QATAR("QA"),    REUNION("RE"),    ROMANIA("RO"),    RUSSIAN_FEDERATION("RU"),    RWANDA("RW"),    SAINT_BARTHELEMY("BL"),    SAINT_HELENA("SH"),    SAINT_KITTS_AND_NEVIS("KN"),    SAINT_LUCIA("LC"),    SAINT_MARTIN("MF"),    SAINT_PIERRE_AND_MIQUELON("PM"),    SAINT_VINCENT_AND_THE_GRENADINES("VC"),    SAMOA("WS"),    SAN_MARINO("SM"),    SAO_TOME_AND_PRINCIPE("ST"),    SAUDI_ARABIA("SA"),    SENEGAL("SN"),    SERBIA("RS"),    SEYCHELLES("SC"),    SIERRA_LEONE("SL"),    SINGAPORE("SG"),    SINT_MAARTEN("SX"),    SLOVAKIA("SK"),    SLOVENIA("SI"),    SOLOMON_ISLANDS("SB"),    SOMALIA("SO"),    SOUTH_AFRICA("ZA"),    SOUTH_GEORGIA_AND_THE_SOUTH_SANDWICH_ISLANDS("GS"),    SOUTH_KOREA("KR"),    SOUTH_SUDAN("SS"),    SPAIN("ES"),    SRI_LANKA("LK"),    SUDAN("SD"),    SURINAME("SR"),    SVALBARD_AND_JAN_MAYEN("SJ"),    SWAZILAND("SZ"),    SWEDEN("SE"),    SWITZERLAND("CH"),    SYRIAN_ARAB_REPUBLIC("SY"),    TAIWAN("TW"),    TAJIKISTAN("TJ"),    TANZANIA("TZ"),    THAILAND("TH"),    THE_DEMOCRATIC_REPUBLIC_OF_THE_CONGO("CD"),    TIMOR_LESTE("TL"),    TOGO("TG"),    TOKELAU("TK"),    TONGA("TO"),    TRINIDAD_AND_TOBAGO("TT"),    TUNISIA("TN"),    TURKEY("TR"),    TURKMENISTAN("TM"),    TURKS_AND_CAICOS_ISLANDS("TC"),    TUVALU("TV"),    UGANDA("UG"),    UKRAINE("UA"),    UNITED_ARAB_EMIRATES("AE"),    UNITED_KINGDOM("GB"),    UNITED_STATES("US"),    UNITED_STATES_MINOR_OUTLYING_ISLANDS("UM"),    URUGUAY("UY"),    US_VIRGIN_ISLANDS("VI"),    UZBEKISTAN("UZ"),    VANUATU("VU"),    VATICAN_CITY_STATE("VA"),    VENEZUELA("VE"),    VIET_NAM("VN"),    WALLIS_AND_FUTUNA("WF"),    WESTERN_SAHARA("EH"),    YEMEN("YE"),    ZAMBIA("ZM"),    ZIMBABWE("ZW");    private final String code;    private IsoCountry(String code) {        this.code = code;    }    /**     * <p>Returns this country ISO 3166-1-alpha-2 code.</p>     *     * @return a non null and 2 characters length string     */    public String getCode() {        return code;    }    /**     * <p>Translate the given ISO 3166-1-alpha-2 code to an IsoCountry.</p>     *     * <p>This method is not case sensitive.</p>     *     * @param code A non-null String.     * @return the country having the given ISO 3166-1-alpha-2 code, or null if it does not exist     */    public static IsoCountry fromCode(String code) {        String cleanedCode = (code == null ? null : code.toUpperCase());        if (cleanedCode == null || cleanedCode.length() != 2) {            return null;        }        for (IsoCountry country : values()) {            if (country.getCode().equals(cleanedCode)) {                return country;            }        }        return null;    }}