Instead of iterating over Java's Timezones, here's a much simplified list that you can use. These map directly to the Java timezones.
Africa/Algiers
Africa/Cairo
Africa/Casablanca
Africa/Harare
Africa/Johannesburg
Africa/Lagos
Africa/Nairobi
Africa/Windhoek
America/Bogota
America/Buenos_Aires
America/Caracas
America/Chihuahua
America/Godthab
America/Guatemala
America/Manaus
America/Mexico_City
America/Montevideo
America/Santiago
America/Sao_Paulo
America/Tijuana
Asia/Amman
Asia/Baghdad
Asia/Baku
Asia/Bangkok
Asia/Beirut
Asia/Calcutta
Asia/Colombo
Asia/Dhaka
Asia/Dubai
Asia/Ho_Chi_Minh
Asia/Hong_Kong
Asia/Irkutsk
Asia/Istanbul
Asia/Jakarta
Asia/Jerusalem
Asia/Kabul
Asia/Karachi
Asia/Kathmandu
Asia/Krasnoyarsk
Asia/Kuala_Lumpur
Asia/Kuwait
Asia/Magadan
Asia/Muscat
Asia/Novosibirsk
Asia/Qatar
Asia/Rangoon
Asia/Seoul
Asia/Shanghai
Asia/Singapore
Asia/Taipei
Asia/Tbilisi
Asia/Tehran
Asia/Tokyo
Asia/Vladivostok
Asia/Yakutsk
Asia/Yekaterinburg
Asia/Yerevan
Atlantic/Azores
Atlantic/Cape_Verde
Atlantic/South_Georgia
Australia/Adelaide
Australia/Brisbane
Australia/Canberra
Australia/Darwin
Australia/Hobart
Australia/Melbourne
Australia/NSW
Australia/Perth
Australia/Queensland
Australia/Sydney
Brazil/East
Canada/Atlantic
Canada/Central
Canada/Eastern
Canada/Mountain
Canada/Newfoundland
Canada/Pacific
Europe/Amsterdam
Europe/Andorra
Europe/Athens
Europe/Belfast
Europe/Belgrade
Europe/Berlin
Europe/Brussels
Europe/Budapest
Europe/Dublin
Europe/Helsinki
Europe/Kiev
Europe/Lisbon
Europe/London
Europe/Luxembourg
Europe/Madrid
Europe/Minsk
Europe/Monaco
Europe/Moscow
Europe/Oslo
Europe/Paris
Europe/Rome
Europe/Stockholm
Europe/Vienna
Europe/Warsaw
Europe/Zurich
Pacific/Auckland
Pacific/Fiji
Pacific/Guam
Pacific/Midway
Pacific/Tongatapu
US/Alaska
US/Arizona
US/Central
US/East-Indiana
US/Eastern
US/Hawaii
US/Mountain
US/Pacific