In Java How to Extract Exact Domain Name from Url

in java how to extract exact domain name from url

A solution is extracting host part and then go left from the end while there is a TLD string at the start:

public static String extractDomainName(String base_url) throws URISyntaxException {
    URI siteURI =
            new URI(base_url);
    base_url = siteURI.getHost();
    base_url = base_url.startsWith("www.") ? base_url.substring(4) : base_url;

    String pattern_exceptDot = "[^.]*";
    String pattern_base = pattern_exceptDot + "\\." + pattern_exceptDot;
    String patternCurrent = pattern_base;

    String base_url_temp = base_url;
    Pattern pattern = Pattern.compile("(" + pattern_base + ")$");
    Matcher matcher = pattern.matcher(base_url);
    if (matcher.find())
        base_url_temp = matcher.group(0);
    boolean shouldLoopTLd = true;
    while (shouldLoopTLd)
        for (String tld : Utility.TLDList()) {
            shouldLoopTLd = false;
            if (base_url_temp.toLowerCase().startsWith(tld.toLowerCase() + ".")) {
                shouldLoopTLd = true;
                patternCurrent = pattern_exceptDot + "\\." + patternCurrent;
                pattern = Pattern.compile("(" + patternCurrent + ")$");
                matcher = pattern.matcher(base_url);
                matcher = matcher.reset();
                if (matcher.find())
                    base_url_temp = matcher.group(0);
                break;
            }
        }
    base_url = base_url_temp;
    return base_url;
}

While method TLDList() returns a list of main domain types, such as 'IR','COM',...

    /**
 * Returnes list of TLD (Top Level Domain, such as 'ir','com')
 *
 * @return
 */
public static List<String> TLDList() {
    return Arrays.asList(new String[]{"AAA", "AARP", "ABARTH", "ABB", "ABBOTT", "ABBVIE", "ABC", "ABLE", "ABOGADO", "ABUDHABI", "AC", "ACADEMY", "ACCENTURE", "ACCOUNTANT", "ACCOUNTANTS", "ACO", "ACTIVE", "ACTOR", "AD", "ADAC", "ADS", "ADULT", "AE", "AEG", "AERO", "AETNA", "AF", "AFAMILYCOMPANY", "AFL", "AFRICA", "AG", "AGAKHAN", "AGENCY", "AI", "AIG", "AIGO", "AIRBUS", "AIRFORCE", "AIRTEL", "AKDN", "AL", "ALFAROMEO", "ALIBABA", "ALIPAY", "ALLFINANZ", "ALLSTATE", "ALLY", "ALSACE", "ALSTOM", "AM", "AMERICANEXPRESS", "AMERICANFAMILY", "AMEX", "AMFAM", "AMICA", "AMSTERDAM", "ANALYTICS", "ANDROID", "ANQUAN", "ANZ", "AO", "AOL", "APARTMENTS", "APP", "APPLE", "AQ", "AQUARELLE", "AR", "ARAB", "ARAMCO", "ARCHI", "ARMY", "ARPA", "ART", "ARTE", "AS", "ASDA", "ASIA", "ASSOCIATES", "AT", "ATHLETA", "ATTORNEY", "AU", "AUCTION", "AUDI", "AUDIBLE", "AUDIO", "AUSPOST", "AUTHOR", "AUTO", "AUTOS", "AVIANCA", "AW", "AWS", "AX", "AXA", "AZ", "AZURE", "BA", "BABY", "BAIDU", "BANAMEX", "BANANAREPUBLIC", "BAND", "BANK", "BAR", "BARCELONA", "BARCLAYCARD", "BARCLAYS", "BAREFOOT", "BARGAINS", "BASEBALL", "BASKETBALL", "BAUHAUS", "BAYERN", "BB", "BBC", "BBT", "BBVA", "BCG", "BCN", "BD", "BE", "BEATS", "BEAUTY", "BEER", "BENTLEY", "BERLIN", "BEST", "BESTBUY", "BET", "BF", "BG", "BH", "BHARTI", "BI", "BIBLE", "BID", "BIKE", "BING", "BINGO", "BIO", "BIZ", "BJ", "BLACK", "BLACKFRIDAY", "BLANCO", "BLOCKBUSTER", "BLOG", "BLOOMBERG", "BLUE", "BM", "BMS", "BMW", "BN", "BNL", "BNPPARIBAS", "BO", "BOATS", "BOEHRINGER", "BOFA", "BOM", "BOND", "BOO", "BOOK", "BOOKING", "BOSCH", "BOSTIK", "BOSTON", "BOT", "BOUTIQUE", "BOX", "BR", "BRADESCO", "BRIDGESTONE", "BROADWAY", "BROKER", "BROTHER", "BRUSSELS", "BS", "BT", "BUDAPEST", "BUGATTI", "BUILD", "BUILDERS", "BUSINESS", "BUY", "BUZZ", "BV", "BW", "BY", "BZ", "BZH", "CA", "CAB", "CAFE", "CAL", "CALL", "CALVINKLEIN", "CAM", "CAMERA", "CAMP", "CANCERRESEARCH", "CANON", "CAPETOWN", "CAPITAL", "CAPITALONE", "CAR", "CARAVAN", "CARDS", "CARE", "CAREER", "CAREERS", "CARS", "CARTIER", "CASA", "CASE", "CASEIH", "CASH", "CASINO", "CAT", "CATERING", "CATHOLIC", "CBA", "CBN", "CBRE", "CBS", "CC", "CD", "CEB", "CENTER", "CEO", "CERN", "CF", "CFA", "CFD", "CG", "CH", "CHANEL", "CHANNEL", "CHARITY", "CHASE", "CHAT", "CHEAP", "CHINTAI", "CHRISTMAS", "CHROME", "CHRYSLER", "CHURCH", "CI", "CIPRIANI", "CIRCLE", "CISCO", "CITADEL", "CITI", "CITIC", "CITY", "CITYEATS", "CK", "CL", "CLAIMS", "CLEANING", "CLICK", "CLINIC", "CLINIQUE", "CLOTHING", "CLOUD", "CLUB", "CLUBMED", "CM", "CN", "CO", "COACH", "CODES", "COFFEE", "COLLEGE", "COLOGNE", "COM", "COMCAST", "COMMBANK", "COMMUNITY", "COMPANY", "COMPARE", "COMPUTER", "COMSEC", "CONDOS", "CONSTRUCTION", "CONSULTING", "CONTACT", "CONTRACTORS", "COOKING", "COOKINGCHANNEL", "COOL", "COOP", "CORSICA", "COUNTRY", "COUPON", "COUPONS", "COURSES", "CR", "CREDIT", "CREDITCARD", "CREDITUNION", "CRICKET", "CROWN", "CRS", "CRUISE", "CRUISES", "CSC", "CU", "CUISINELLA", "CV", "CW", "CX", "CY", "CYMRU", "CYOU", "CZ", "DABUR", "DAD", "DANCE", "DATA", "DATE", "DATING", "DATSUN", "DAY", "DCLK", "DDS", "DE", "DEAL", "DEALER", "DEALS", "DEGREE", "DELIVERY", "DELL", "DELOITTE", "DELTA", "DEMOCRAT", "DENTAL", "DENTIST", "DESI", "DESIGN", "DEV", "DHL", "DIAMONDS", "DIET", "DIGITAL", "DIRECT", "DIRECTORY", "DISCOUNT", "DISCOVER", "DISH", "DIY", "DJ", "DK", "DM", "DNP", "DO", "DOCS", "DOCTOR", "DODGE", "DOG", "DOHA", "DOMAINS", "DOT", "DOWNLOAD", "DRIVE", "DTV", "DUBAI", "DUCK", "DUNLOP", "DUNS", "DUPONT", "DURBAN", "DVAG", "DVR", "DZ", "EARTH", "EAT", "EC", "ECO", "EDEKA", "EDU", "EDUCATION", "EE", "EG", "EMAIL", "EMERCK", "ENERGY", "ENGINEER", "ENGINEERING", "ENTERPRISES", "EPOST", "EPSON", "EQUIPMENT", "ER", "ERICSSON", "ERNI", "ES", "ESQ", "ESTATE", "ESURANCE", "ET", "ETISALAT", "EU", "EUROVISION", "EUS", "EVENTS", "EVERBANK", "EXCHANGE", "EXPERT", "EXPOSED", "EXPRESS", "EXTRASPACE", "FAGE", "FAIL", "FAIRWINDS", "FAITH", "FAMILY", "FAN", "FANS", "FARM", "FARMERS", "FASHION", "FAST", "FEDEX", "FEEDBACK", "FERRARI", "FERRERO", "FI", "FIAT", "FIDELITY", "FIDO", "FILM", "FINAL", "FINANCE", "FINANCIAL", "FIRE", "FIRESTONE", "FIRMDALE", "FISH", "FISHING", "FIT", "FITNESS", "FJ", "FK", "FLICKR", "FLIGHTS", "FLIR", "FLORIST", "FLOWERS", "FLY", "FM", "FO", "FOO", "FOOD", "FOODNETWORK", "FOOTBALL", "FORD", "FOREX", "FORSALE", "FORUM", "FOUNDATION", "FOX", "FR", "FREE", "FRESENIUS", "FRL", "FROGANS", "FRONTDOOR", "FRONTIER", "FTR", "FUJITSU", "FUJIXEROX", "FUN", "FUND", "FURNITURE", "FUTBOL", "FYI", "GA", "GAL", "GALLERY", "GALLO", "GALLUP", "GAME", "GAMES", "GAP", "GARDEN", "GB", "GBIZ", "GD", "GDN", "GE", "GEA", "GENT", "GENTING", "GEORGE", "GF", "GG", "GGEE", "GH", "GI", "GIFT", "GIFTS", "GIVES", "GIVING", "GL", "GLADE", "GLASS", "GLE", "GLOBAL", "GLOBO", "GM", "GMAIL", "GMBH", "GMO", "GMX", "GN", "GODADDY", "GOLD", "GOLDPOINT", "GOLF", "GOO", "GOODHANDS", "GOODYEAR", "GOOG", "GOOGLE", "GOP", "GOT", "GOV", "GP", "GQ", "GR", "GRAINGER", "GRAPHICS", "GRATIS", "GREEN", "GRIPE", "GROCERY", "GROUP", "GS", "GT", "GU", "GUARDIAN", "GUCCI", "GUGE", "GUIDE", "GUITARS", "GURU", "GW", "GY", "HAIR", "HAMBURG", "HANGOUT", "HAUS", "HBO", "HDFC", "HDFCBANK", "HEALTH", "HEALTHCARE", "HELP", "HELSINKI", "HERE", "HERMES", "HGTV", "HIPHOP", "HISAMITSU", "HITACHI", "HIV", "HK", "HKT", "HM", "HN", "HOCKEY", "HOLDINGS", "HOLIDAY", "HOMEDEPOT", "HOMEGOODS", "HOMES", "HOMESENSE", "HONDA", "HONEYWELL", "HORSE", "HOSPITAL", "HOST", "HOSTING", "HOT", "HOTELES", "HOTELS", "HOTMAIL", "HOUSE", "HOW", "HR", "HSBC", "HT", "HU", "HUGHES", "HYATT", "HYUNDAI", "IBM", "ICBC", "ICE", "ICU", "ID", "IE", "IEEE", "IFM", "IKANO", "IL", "IM", "IMAMAT", "IMDB", "IMMO", "IMMOBILIEN", "IN", "INDUSTRIES", "INFINITI", "INFO", "ING", "INK", "INSTITUTE", "INSURANCE", "INSURE", "INT", "INTEL", "INTERNATIONAL", "INTUIT", "INVESTMENTS", "IO", "IPIRANGA", "IQ", "IR", "IRISH", "IS", "ISELECT", "ISMAILI", "IST", "ISTANBUL", "IT", "ITAU", "ITV", "IVECO", "IWC", "JAGUAR", "JAVA", "JCB", "JCP", "JE", "JEEP", "JETZT", "JEWELRY", "JIO", "JLC", "JLL", "JM", "JMP", "JNJ", "JO", "JOBS", "JOBURG", "JOT", "JOY", "JP", "JPMORGAN", "JPRS", "JUEGOS", "JUNIPER", "KAUFEN", "KDDI", "KE", "KERRYHOTELS", "KERRYLOGISTICS", "KERRYPROPERTIES", "KFH", "KG", "KH", "KI", "KIA", "KIM", "KINDER", "KINDLE", "KITCHEN", "KIWI", "KM", "KN", "KOELN", "KOMATSU", "KOSHER", "KP", "KPMG", "KPN", "KR", "KRD", "KRED", "KUOKGROUP", "KW", "KY", "KYOTO", "KZ", "LA", "LACAIXA", "LADBROKES", "LAMBORGHINI", "LAMER", "LANCASTER", "LANCIA", "LANCOME", "LAND", "LANDROVER", "LANXESS", "LASALLE", "LAT", "LATINO", "LATROBE", "LAW", "LAWYER", "LB", "LC", "LDS", "LEASE", "LECLERC", "LEFRAK", "LEGAL", "LEGO", "LEXUS", "LGBT", "LI", "LIAISON", "LIDL", "LIFE", "LIFEINSURANCE", "LIFESTYLE", "LIGHTING", "LIKE", "LILLY", "LIMITED", "LIMO", "LINCOLN", "LINDE", "LINK", "LIPSY", "LIVE", "LIVING", "LIXIL", "LK", "LLC", "LOAN", "LOANS", "LOCKER", "LOCUS", "LOFT", "LOL", "LONDON", "LOTTE", "LOTTO", "LOVE", "LPL", "LPLFINANCIAL", "LR", "LS", "LT", "LTD", "LTDA", "LU", "LUNDBECK", "LUPIN", "LUXE", "LUXURY", "LV", "LY", "MA", "MACYS", "MADRID", "MAIF", "MAISON", "MAKEUP", "MAN", "MANAGEMENT", "MANGO", "MAP", "MARKET", "MARKETING", "MARKETS", "MARRIOTT", "MARSHALLS", "MASERATI", "MATTEL", "MBA", "MC", "MCKINSEY", "MD", "ME", "MED", "MEDIA", "MEET", "MELBOURNE", "MEME", "MEMORIAL", "MEN", "MENU", "MERCKMSD", "METLIFE", "MG", "MH", "MIAMI", "MICROSOFT", "MIL", "MINI", "MINT", "MIT", "MITSUBISHI", "MK", "ML", "MLB", "MLS", "MM", "MMA", "MN", "MO", "MOBI", "MOBILE", "MOBILY", "MODA", "MOE", "MOI", "MOM", "MONASH", "MONEY", "MONSTER", "MOPAR", "MORMON", "MORTGAGE", "MOSCOW", "MOTO", "MOTORCYCLES", "MOV", "MOVIE", "MOVISTAR", "MP", "MQ", "MR", "MS", "MSD", "MT", "MTN", "MTR", "MU", "MUSEUM", "MUTUAL", "MV", "MW", "MX", "MY", "MZ", "NA", "NAB", "NADEX", "NAGOYA", "NAME", "NATIONWIDE", "NATURA", "NAVY", "NBA", "NC", "NE", "NEC", "NET", "NETBANK", "NETFLIX", "NETWORK", "NEUSTAR", "NEW", "NEWHOLLAND", "NEWS", "NEXT", "NEXTDIRECT", "NEXUS", "NF", "NFL", "NG", "NGO", "NHK", "NI", "NICO", "NIKE", "NIKON", "NINJA", "NISSAN", "NISSAY", "NL", "NO", "NOKIA", "NORTHWESTERNMUTUAL", "NORTON", "NOW", "NOWRUZ", "NOWTV", "NP", "NR", "NRA", "NRW", "NTT", "NU", "NYC", "NZ", "OBI", "OBSERVER", "OFF", "OFFICE", "OKINAWA", "OLAYAN", "OLAYANGROUP", "OLDNAVY", "OLLO", "OM", "OMEGA", "ONE", "ONG", "ONL", "ONLINE", "ONYOURSIDE", "OOO", "OPEN", "ORACLE", "ORANGE", "ORG", "ORGANIC", "ORIGINS", "OSAKA", "OTSUKA", "OTT", "OVH", "PA", "PAGE", "PANASONIC", "PANERAI", "PARIS", "PARS", "PARTNERS", "PARTS", "PARTY", "PASSAGENS", "PAY", "PCCW", "PE", "PET", "PF", "PFIZER", "PG", "PH", "PHARMACY", "PHD", "PHILIPS", "PHONE", "PHOTO", "PHOTOGRAPHY", "PHOTOS", "PHYSIO", "PIAGET", "PICS", "PICTET", "PICTURES", "PID", "PIN", "PING", "PINK", "PIONEER", "PIZZA", "PK", "PL", "PLACE", "PLAY", "PLAYSTATION", "PLUMBING", "PLUS", "PM", "PN", "PNC", "POHL", "POKER", "POLITIE", "PORN", "POST", "PR", "PRAMERICA", "PRAXI", "PRESS", "PRIME", "PRO", "PROD", "PRODUCTIONS", "PROF", "PROGRESSIVE", "PROMO", "PROPERTIES", "PROPERTY", "PROTECTION", "PRU", "PRUDENTIAL", "PS", "PT", "PUB", "PW", "PWC", "PY", "QA", "QPON", "QUEBEC", "QUEST", "QVC", "RACING", "RADIO", "RAID", "RE", "READ", "REALESTATE", "REALTOR", "REALTY", "RECIPES", "RED", "REDSTONE", "REDUMBRELLA", "REHAB", "REISE", "REISEN", "REIT", "RELIANCE", "REN", "RENT", "RENTALS", "REPAIR", "REPORT", "REPUBLICAN", "REST", "RESTAURANT", "REVIEW", "REVIEWS", "REXROTH", "RICH", "RICHARDLI", "RICOH", "RIGHTATHOME", "RIL", "RIO", "RIP", "RMIT", "RO", "ROCHER", "ROCKS", "RODEO", "ROGERS", "ROOM", "RS", "RSVP", "RU", "RUGBY", "RUHR", "RUN", "RW", "RWE", "RYUKYU", "SA", "SAARLAND", "SAFE", "SAFETY", "SAKURA", "SALE", "SALON", "SAMSCLUB", "SAMSUNG", "SANDVIK", "SANDVIKCOROMANT", "SANOFI", "SAP", "SARL", "SAS", "SAVE", "SAXO", "SB", "SBI", "SBS", "SC", "SCA", "SCB", "SCHAEFFLER", "SCHMIDT", "SCHOLARSHIPS", "SCHOOL", "SCHULE", "SCHWARZ", "SCIENCE", "SCJOHNSON", "SCOR", "SCOT", "SD", "SE", "SEARCH", "SEAT", "SECURE", "SECURITY", "SEEK", "SELECT", "SENER", "SERVICES", "SES", "SEVEN", "SEW", "SEX", "SEXY", "SFR", "SG", "SH", "SHANGRILA", "SHARP", "SHAW", "SHELL", "SHIA", "SHIKSHA", "SHOES", "SHOP", "SHOPPING", "SHOUJI", "SHOW", "SHOWTIME", "SHRIRAM", "SI", "SILK", "SINA", "SINGLES", "SITE", "SJ", "SK", "SKI", "SKIN", "SKY", "SKYPE", "SL", "SLING", "SM", "SMART", "SMILE", "SN", "SNCF", "SO", "SOCCER", "SOCIAL", "SOFTBANK", "SOFTWARE", "SOHU", "SOLAR", "SOLUTIONS", "SONG", "SONY", "SOY", "SPACE", "SPIEGEL", "SPORT", "SPOT", "SPREADBETTING", "SR", "SRL", "SRT", "ST", "STADA", "STAPLES", "STAR", "STARHUB", "STATEBANK", "STATEFARM", "STATOIL", "STC", "STCGROUP", "STOCKHOLM", "STORAGE", "STORE", "STREAM", "STUDIO", "STUDY", "STYLE", "SU", "SUCKS", "SUPPLIES", "SUPPLY", "SUPPORT", "SURF", "SURGERY", "SUZUKI", "SV", "SWATCH", "SWIFTCOVER", "SWISS", "SX", "SY", "SYDNEY", "SYMANTEC", "SYSTEMS", "SZ", "TAB", "TAIPEI", "TALK", "TAOBAO", "TARGET", "TATAMOTORS", "TATAR", "TATTOO", "TAX", "TAXI", "TC", "TCI", "TD", "TDK", "TEAM", "TECH", "TECHNOLOGY", "TEL", "TELECITY", "TELEFONICA", "TEMASEK", "TENNIS", "TEVA", "TF", "TG", "TH", "THD", "THEATER", "THEATRE", "TIAA", "TICKETS", "TIENDA", "TIFFANY", "TIPS", "TIRES", "TIROL", "TJ", "TJMAXX", "TJX", "TK", "TKMAXX", "TL", "TM", "TMALL", "TN", "TO", "TODAY", "TOKYO", "TOOLS", "TOP", "TORAY", "TOSHIBA", "TOTAL", "TOURS", "TOWN", "TOYOTA", "TOYS", "TR", "TRADE", "TRADING", "TRAINING", "TRAVEL", "TRAVELCHANNEL", "TRAVELERS", "TRAVELERSINSURANCE", "TRUST", "TRV", "TT", "TUBE", "TUI", "TUNES", "TUSHU", "TV", "TVS", "TW", "TZ", "UA", "UBANK", "UBS", "UCONNECT", "UG", "UK", "UNICOM", "UNIVERSITY", "UNO", "UOL", "UPS", "US", "UY", "UZ", "VA", "VACATIONS", "VANA", "VANGUARD", "VC", "VE", "VEGAS", "VENTURES", "VERISIGN", "VERSICHERUNG", "VET", "VG", "VI", "VIAJES", "VIDEO", "VIG", "VIKING", "VILLAS", "VIN", "VIP", "VIRGIN", "VISA", "VISION", "VISTA", "VISTAPRINT", "VIVA", "VIVO", "VLAANDEREN", "VN", "VODKA", "VOLKSWAGEN", "VOLVO", "VOTE", "VOTING", "VOTO", "VOYAGE", "VU", "VUELOS", "WALES", "WALMART", "WALTER", "WANG", "WANGGOU", "WARMAN", "WATCH", "WATCHES", "WEATHER", "WEATHERCHANNEL", "WEBCAM", "WEBER", "WEBSITE", "WED", "WEDDING", "WEIBO", "WEIR", "WF", "WHOSWHO", "WIEN", "WIKI", "WILLIAMHILL", "WIN", "WINDOWS", "WINE", "WINNERS", "WME", "WOLTERSKLUWER", "WOODSIDE", "WORK", "WORKS", "WORLD", "WOW", "WS", "WTC", "WTF", "XBOX", "XEROX", "XFINITY", "XIHUAN", "XIN", "XN--11B4C3D", "XN--1CK2E1B", "XN--1QQW23A", "XN--2SCRJ9C", "XN--30RR7Y", "XN--3BST00M", "XN--3DS443G", "XN--3E0B707E", "XN--3HCRJ9C", "XN--3OQ18VL8PN36A", "XN--3PXU8K", "XN--42C2D9A", "XN--45BR5CYL", "XN--45BRJ9C", "XN--45Q11C", "XN--4GBRIM", "XN--54B7FTA0CC", "XN--55QW42G", "XN--55QX5D", "XN--5SU34J936BGSG", "XN--5TZM5G", "XN--6FRZ82G", "XN--6QQ986B3XL", "XN--80ADXHKS", "XN--80AO21A", "XN--80AQECDR1A", "XN--80ASEHDB", "XN--80ASWG", "XN--8Y0A063A", "XN--90A3AC", "XN--90AE", "XN--90AIS", "XN--9DBQ2A", "XN--9ET52U", "XN--9KRT00A", "XN--B4W605FERD", "XN--BCK1B9A5DRE4C", "XN--C1AVG", "XN--C2BR7G", "XN--CCK2B3B", "XN--CG4BKI", "XN--CLCHC0EA0B2G2A9GCD", "XN--CZR694B", "XN--CZRS0T", "XN--CZRU2D", "XN--D1ACJ3B", "XN--D1ALF", "XN--E1A4C", "XN--ECKVDTC9D", "XN--EFVY88H", "XN--ESTV75G", "XN--FCT429K", "XN--FHBEI", "XN--FIQ228C5HS", "XN--FIQ64B", "XN--FIQS8S", "XN--FIQZ9S", "XN--FJQ720A", "XN--FLW351E", "XN--FPCRJ9C3D", "XN--FZC2C9E2C", "XN--FZYS8D69UVGM", "XN--G2XX48C", "XN--GCKR3F0F", "XN--GECRJ9C", "XN--GK3AT1E", "XN--H2BREG3EVE", "XN--H2BRJ9C", "XN--H2BRJ9C8C", "XN--HXT814E", "XN--I1B6B1A6A2E", "XN--IMR513N", "XN--IO0A7I", "XN--J1AEF", "XN--J1AMH", "XN--J6W193G", "XN--JLQ61U9W7B", "XN--JVR189M", "XN--KCRX77D1X4A", "XN--KPRW13D", "XN--KPRY57D", "XN--KPU716F", "XN--KPUT3I", "XN--L1ACC", "XN--LGBBAT1AD8J", "XN--MGB9AWBF", "XN--MGBA3A3EJT", "XN--MGBA3A4F16A", "XN--MGBA7C0BBN0A", "XN--MGBAAKC7DVF", "XN--MGBAAM7A8H", "XN--MGBAB2BD", "XN--MGBAI9AZGQP6J", "XN--MGBAYH7GPA", "XN--MGBB9FBPOB", "XN--MGBBH1A", "XN--MGBBH1A71E", "XN--MGBC0A9AZCG", "XN--MGBCA7DZDO", "XN--MGBERP4A5D4AR", "XN--MGBGU82A", "XN--MGBI4ECEXP", "XN--MGBPL2FH", "XN--MGBT3DHD", "XN--MGBTX2B", "XN--MGBX4CD0AB", "XN--MIX891F", "XN--MK1BU44C", "XN--MXTQ1M", "XN--NGBC5AZD", "XN--NGBE9E0A", "XN--NGBRX", "XN--NODE", "XN--NQV7F", "XN--NQV7FS00EMA", "XN--NYQY26A", "XN--O3CW4H", "XN--OGBPF8FL", "XN--OTU796D", "XN--P1ACF", "XN--P1AI", "XN--PBT977C", "XN--PGBS0DH", "XN--PSSY2U", "XN--Q9JYB4C", "XN--QCKA1PMC", "XN--QXAM", "XN--RHQV96G", "XN--ROVU88B", "XN--RVC1E0AM3E", "XN--S9BRJ9C", "XN--SES554G", "XN--T60B56A", "XN--TCKWE", "XN--TIQ49XQYJ", "XN--UNUP4Y", "XN--VERMGENSBERATER-CTB", "XN--VERMGENSBERATUNG-PWB", "XN--VHQUV", "XN--VUQ861B", "XN--W4R85EL8FHU5DNRA", "XN--W4RS40L", "XN--WGBH1C", "XN--WGBL6A", "XN--XHQ521B", "XN--XKC2AL3HYE2A", "XN--XKC2DL3A5EE0H", "XN--Y9A3AQ", "XN--YFRO4I67O", "XN--YGBI2AMMX", "XN--ZFR164B", "XPERIA", "XXX", "XYZ", "YACHTS", "YAHOO", "YAMAXUN", "YANDEX", "YE", "YODOBASHI", "YOGA", "YOKOHAMA", "YOU", "YOUTUBE", "YT", "YUN", "ZA", "ZAPPOS", "ZARA", "ZERO", "ZIP", "ZIPPO", "ZM", "ZONE", "ZUERICH", "ZW"});
}

The TLD list is from here.

Get domain name from given url

If you want to parse a URL, use java.net.URI. java.net.URL has a bunch of problems -- its equals method does a DNS lookup which means code using it can be vulnerable to denial of service attacks when used with untrusted inputs.

"Mr. Gosling -- why did you make url equals suck?" explains one such problem. Just get in the habit of using java.net.URI instead.

public static String getDomainName(String url) throws URISyntaxException {
    URI uri = new URI(url);
    String domain = uri.getHost();
    return domain.startsWith("www.") ? domain.substring(4) : domain;
}

should do what you want.

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Though It seems to work fine, is there any better approach or are there some edge cases, that could fail.

Your code as written fails for the valid URLs:

• httpfoo/bar -- relative URL with a path component that starts with http.
• HTTP://example.com/ -- protocol is case-insensitive.
• //example.com/ -- protocol relative URL with a host
• www/foo -- a relative URL with a path component that starts with www
• wwwexample.com -- domain name that does not starts with www. but starts with www.

Hierarchical URLs have a complex grammar. If you try to roll your own parser without carefully reading RFC 3986, you will probably get it wrong. Just use the one that's built into the core libraries.

If you really need to deal with messy inputs that java.net.URI rejects, see RFC 3986 Appendix B:

Appendix B. Parsing a URI Reference with a Regular Expression

As the "first-match-wins" algorithm is identical to the "greedy"
disambiguation method used by POSIX regular expressions, it is
natural and commonplace to use a regular expression for parsing the
potential five components of a URI reference.

The following line is the regular expression for breaking-down a
well-formed URI reference into its components.

  ^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?
   12            3  4          5       6  7        8 9

The numbers in the second line above are only to assist readability;
they indicate the reference points for each subexpression (i.e., each
paired parenthesis).

Extract host name/domain name from URL string

You can use the java.net.URI-class to extract the hostname from the string.

Here below is a method from which you can extract your hostname from a string.

public String getHostName(String url) {
    URI uri = new URI(url);
    String hostname = uri.getHost();
    // to provide faultproof result, check if not null then return only hostname, without www.
    if (hostname != null) {
        return hostname.startsWith("www.") ? hostname.substring(4) : hostname;
    }
    return hostname;
}

This above gives you the hostname, and is faultproof if your hostname does start with either hostname.com/... or www.hostname.com/..., which will return with 'hostname'.

If the given url is invalid (undefined hostname), it returns with null.

How to get domain name from URL

I once had to write such a regex for a company I worked for. The solution was this:

• Get a list of every ccTLD and gTLD available. Your first stop should be IANA. The list from Mozilla looks great at first sight, but lacks ac.uk for example so for this it is not really usable.
• Join the list like the example below. A warning: Ordering is important! If org.uk would appear after uk then example.org.uk would match org instead of example.

Example regex:

.*([^\.]+)(com|net|org|info|coop|int|co\.uk|org\.uk|ac\.uk|uk|__and so on__)$

This worked really well and also matched weird, unofficial top-levels like de.com and friends.

The upside:

• Very fast if regex is optimally ordered

The downside of this solution is of course:

• Handwritten regex which has to be updated manually if ccTLDs change or get added. Tedious job!
• Very large regex so not very readable.

Get domain without subdomains in Java?

This is tricky because the URL class can only get you so far. It gives you the hostname and then it's up to you to extract the domain name minus the subdomain.

To identify the domain name here you need to know what TLDs (top level domains like .com, .co etc.) or ccTLDs (country code TLDs like .co.uk, .uk etc.) you're expecting beforehand because that would determine from where (which . dot) your domain name starts.

For example, the following regex:

(?<=.)[^.]+\.(com|co(\.uk)?|uk)$

would identify the following domain names for you:

www.google.com

mail.google.co

www.google.co.uk

www.sub.google.uk

A more generic solution would require to make assumptions beforehand like a TLD or ccTLD will have no more than two or three characters to differentiate them from the main domain but with newer TLDs like .guru, .photos, .expert, .legal etc. it's not possible to make it work for all the domains anymore.

Extract hostname name from string

There is no need to parse the string, just pass your URL as an argument to URL constructor:

const url = 'http://www.youtube.com/watch?v=ClkQA2Lb_iE';
const { hostname } = new URL(url);

console.assert(hostname === 'www.youtube.com');

Extract file name from Java URL (file: and http/https protocol)?

The URI class properly parses the parts of a URI. For most URLs, you want the path of the URI. In the case of a URI with no slashes, there won’t be any parsing of the parts, so you’ll have to rely on the entire scheme-specific part:

URI uri = new URI(b);
String path = uri.getPath();
if (path == null) {
    path = uri.getSchemeSpecificPart();
}
String filename = path.substring(path.lastIndexOf('/') + 1);

The above should work for all of your URLs.

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