String country = System.getProperty( "user.country" );

String country = Locale.getDefault().getCountry();

java -Duser.language=de -Duser.country=DE -Duser.variant=EURO MainClass

Country Codes
By country flag country code Åland Islands AX Afghanistan AF 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 Ascension SH Australia AU Australian Antarctic Territory 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, Plurinational State of BO Bonaire BQ Bonaire, Sint Eustatius and Saba BQ Bosnia and Herzegovina BA Botswana BW Bouvet Island BV Brazil BR British Indian Ocean Territory IO Brunei Darussalam BN Bulgaria BG Burkina Faso BF Burundi BI Côte d’Ivoire CI Cambodia KH Cameroon CM Canada CA Cape Verde CV Caribbean Netherlands BQ Cayman Islands KY Central African Republic CF Chad TD Channel Islands GB Chile CL China (Mainland) CN Christmas Island CX Cocos (Keeling) Islands CC Colombia CO Comoros KM Congo CG Congo, the Democratic Republic of the CD Cook Islands CK Costa Rica CR Croatia HR Cuba CU Curaçao CW Cyprus CY Czech Republic CZ Czech Republic (obsolete) CS 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 (Malvinas) FK Faroe Islands FO Federal Republic of Somalia SO Fiji FJ Finland FI France FR France metropolitan FX 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 Holy See (Vatican City State) VA Honduras HN Hong Kong HK Hungary HU Iceland IS India IN Indonesia ID Iran, Islamic Republic of IR Iraq IQ Ireland IE Isle of Man IM Israel IL Italy IT Jamaica JM Jan Mayen SJ Japan JP Jersey JE Jordan JO Kazakhstan KZ Kenya KE Kiribati KI Korea, Republic of (South Korea) KR Korea,Democratic People’s Republic of (North Korea) KP Kuwait KW Kyrgyzstan KG Lao People’s Democratic Republic (Laos) LA Latvia LV Lebanon LB Lesotho LS Liberia LR Libya LY Liechtenstein LI Lithuania LT Luxembourg LU Macau MO Macedonia, The Former Yugoslav Republic of 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, Federated States of FM Moldova, Republic of MD Mon aco MC Mongolia MN Montenegro ME Montserrat MS Morocco MA Mozambique MZ Myanmar MM Namibia NA Nauru NR Nepal NP Netherlands NL Netherlands Antilles AN New Caledonia NC New Zealand NZ Nicaragua NI Niger NE Nigeria NG Niue NU Norfolk Island NF Northern Mariana Islands MP Norway NO Oman OM Pakistan PK Palau PW Palestine, State of PS Panama PA Papua New Guinea PG Paraguay PY Peru PE Philippines PH Pitcairn PN Poland PL Portugal PT Puerto Rico PR Qatar QA Réunion RE Romania RO Russian Federation RU Rwanda RW São Tomé and and Príncipe ST Saba BQ Saint Barthélemy BL Saint Eustatius BQ Saint Helena SH Saint Helena, Ascension and Tristan da Cunha SH Saint Kitts and Nevis KN Saint Lucia LC Saint Martin (French part) MF Saint Pierre and Miquelon PM Saint Vincent and the Grenadines VC Samoa WS San Marino SM Saudi Arabia SA Senegal SN Serbia and Montenegro RS Seychelles SC Sierra Leone SL Singapore SG Sint Maarten (Dutch Part) SX Slovakia SK Slovenia SI Solomon Islands SB South Africa ZA South Georgia GS South Georgia and the South Sandwich Islands GS South Sandwich Islands GS 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, Province of China TW Tajikistan TJ Tanzania, United Republic of TZ Thailand TH Timor-Leste TL Togo TG Tokelau TK Tonga TO Trinidad and Tobago TT Tristan da Cunha SH 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 Uzbekistan UZ Vanuatu VU Venezuela, Bolivarian Republic of VE Viet Nam VN Virgin Islands, British VG Virgin Islands, U.S. VI Wallis and Futuna WF Western Sahara EH Yemen YE Zambia ZM Zimbabwe ZW		By code flag code country AD Andorra AE United Arab Emirates AF Afghanistan AG Antigua and Barbuda AI Anguilla AL Albania AM Armenia AN Netherlands Antilles AO Angola AQ Antarctica AR Argentina AS American Samoa AT Austria AU Australia AU Australian Antarctic Territory AW Aruba AX Åland Islands AZ Azerbaijan BA Bosnia and Herzegovina BB Barbados BD Bangladesh BE Belgium BF Burkina Faso BG Bulgaria BH Bahrain BI Burundi BJ Benin BL Saint Barthélemy BM Bermuda BN Brunei Darussalam BO Bolivia, Plurinational State of BQ Bonaire BQ Bonaire, Sint Eustatius and Saba BQ Caribbean Netherlands BQ Saba BQ Saint Eustatius BR Brazil BS Bahamas BT Bhutan BV Bouvet Island BW Botswana BY Belarus BZ Belize CA Canada CC Cocos (Keeling) Islands CD Congo, the Democratic Republic of the CF Central African Republic CG Congo CH Switzerland CI Côte d’Ivoire CK Cook Islands CL Chile CM Cameroon CN China (Mainland) CO Colombia CR Costa Rica CS Czech Republic (obsolete) CU Cuba CV Cape Verde CW Curaçao CX Christmas Island CY Cyprus CZ Czech Republic DE Germany DJ Djibouti DK Denmark DM Dominica DO Dominican Republic DZ Algeria EC Ecuador EE Estonia EG Egypt EH Western Sahara ER Eritrea ES Spain ET Ethiopia FI Finland FJ Fiji FK Falkland Islands (Malvinas) FM Micronesia, Federated States of FO Faroe Islands FR France FX France metropolitan GA Gabon GB Channel Islands GB United Kingdom GD Grenada GE Georgia GF French Guiana GG Guernsey GH Ghana GI Gibraltar GL Greenland GM Gambia GN Guinea GP Guadeloupe GQ Equatorial Guinea GR Greece GS South Georgia GS South Georgia and the South Sandwich Islands GS South Sandwich Islands GT Guatemala GU Guam GW Guinea-Bissau GY Guyana HK Hong Kong HM Heard Island and McDonald Islands HN Honduras HR Croatia HT Haiti HU Hungary ID Indonesia IE Ireland IL Israel IM Isle of Man IN India IO British Indian Ocean Territory IQ Iraq IR Iran, Islamic Republic of IS Iceland IT Italy JE Jersey JM Jamaica JO Jordan JP Japan KE Kenya KG Kyrgyzstan KH Cambodia KI Kiribati KM Comoros KN Saint Kitts and Nevis KP Korea,Democratic People’s Republic of (North Korea) KR Korea, Republic of (South Korea) KW Kuwait KY Cayman Islands KZ Kazakhstan LA Lao People’s Democratic Republic (Laos) LB Lebanon LC Saint Lucia LI Liechtenstein LK Sri Lanka LR Liberia LS Lesotho LT Lithuania LU Luxembourg LV Latvia LY Libya MA Morocco MC Mon aco MD Moldova, Republic of ME Montenegro MF Saint Martin (French part) MG Madagascar MH Marshall Islands MK Macedonia, The Former Yugoslav Republic of ML Mali MM Myanmar MN Mongolia MO Macau MP Northern Mariana Islands MQ Martinique MR Mauritania MS Montserrat MT Malta MU Mauritius MV Maldives MW Malawi MX Mexico MY Malaysia MZ Mozambique NA Namibia NC New Caledonia NE Niger NF Norfolk Island NG Nigeria NI Nicaragua NL Netherlands NO Norway NP Nepal NR Nauru NU Niue NZ New Zealand OM Oman PA Panama PE Peru PF French Polynesia PG Papua New Guinea PH Philippines PK Pakistan PL Poland PM Saint Pierre and Miquelon PN Pitcairn PR Puerto Rico PS Palestine, State of PT Portugal PW Palau PY Paraguay QA Qatar RE Réunion RO Romania RS Serbia and Montenegro RU Russian Federation RW Rwanda SA Saudi Arabia SB Solomon Islands SC Seychelles SD Sudan SE Sweden SG Singapore SH Ascension SH Saint Helena SH Saint Helena, Ascension and Tristan da Cunha SH Tristan da Cunha SI Slovenia SJ Jan Mayen SJ Svalbard and Jan Mayen SK Slovakia SL Sierra Leone SM San Marino SN Senegal SO Federal Republic of Somalia SR Suriname ST São Tomé and and Príncipe SV El Salvador SX Sint Maarten (Dutch Part) SY Syrian Arab Republic SZ Swaziland TC Turks and Caicos Islands TD Chad TF French Southern Territories TG Togo TH Thailand TJ Tajikistan TK Tokelau TL Timor-Leste TM Turkmenistan TN Tunisia TO Tonga TR Turkey TT Trinidad and Tobago TV Tuvalu TW Taiwan, Province of China TZ Tanzania, United Republic of UA Ukraine UG Uganda UM United States (minor outlying islands) US United States UY Uruguay UZ Uzbekistan VA Holy See (Vatican City State) VC Saint Vincent and the Grenadines VE Venezuela, Bolivarian Republic of VG Virgin Islands, British VI Virgin Islands, U.S. VN Viet Nam VU Vanuatu WF Wallis and Futuna WS Samoa YE Yemen YT Mayotte ZA South Africa ZM Zambia ZW Zimbabwe

Country codes overlap province and states codes. For example ca means both Canada and California and skmeans both Slovakia and Saskatchewan.

Most of the flags came compliments of icondrawer.com. Bonaire, Curaçao, St. Maarten, Serbia and