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/** Set Time Zone from args.  Tony Dahlman <adahlman@ecity.net>              */
/*  ** Freeware.  Use at your own risk. **                                   */
/*  Revised 98-03-20.  "TZcheck.java" - a diagnostic tool                    */
/*  Purpose:  1. List supported zones.                                       */
/*            2. Display current default time and zone.                      */
/*            3. Show result of setting a new zone,                          */
/*            4. Show other choices for time zone ID at same offset from GMT.*/
import java.util.*;     // Date, TimeZone
                        // implicitly: SimpleTimeZone, GregorianCalendar 
import java.text.*;     // DateFormat

class TZcheck {
   private static void checkZone( String tzStr) {
      // list supported time zones; check for valid command line arg
      String[] ids = TimeZone.getAvailableIDs();
      boolean found = false;
      for (int i=0; i<ids.length; i++) {
         System.out.print("    " + ids[i] );
         if ( ids[i].compareTo(tzStr)==0 ) 
            found = true;              // arg matches something in the list
         if ( i % 6 == 5 ) 
            System.out.println();      // 6 columns
      }
      System.out.println();
      if ( ! found ) {
         System.out.println("\nZone \""
                           + tzStr 
                           + "\" is not supported.  Please choose an ID from the list.");
         System.out.println("Usage example:  java TZcheck GMT [enter]"); 
         System.exit(0);
      }
   } // end checkZone(..)

   private static void showLocalZoneOptions(TimeZone tz, String tzStr) {
      String[] localids = TimeZone.getAvailableIDs( tz.getRawOffset() );
      System.out.println("\nSupported time zone ID's at " 
                        + tzStr
                        + "'s offset from GMT:\n");
      for (int i=0; i<localids.length; i++) {
         System.out.print("    " + localids[i] );
      }
      System.out.println();
   } // end showLocalZoneOptions(..)

   public static void main(String args[]) {
      String reqZone;
      if ( args.length < 1 ) {
         reqZone = "none";       // dummy arg avoids compareTo(null) in method showZones()
      } else {
         reqZone = args[0];
      }
      System.out.println("Your version of Java supports these TimeZone ID's:\n");
      checkZone(reqZone);

      // Get and show current time and zone, regardless of args
      Date date = new Date();                    // current date and time from host
      DateFormat dateform = DateFormat.getTimeInstance(DateFormat.LONG);  // may return wrong time zone

      dateform.setTimeZone( TimeZone.getDefault() );       // Format and convert for *local* time zone
      System.out.println("\nJava reports your local (default) time as: " 
                        + dateform.format(date) );

      // Show current time in requested zone so user can see if environment settings are correct
      TimeZone newtz = TimeZone.getTimeZone( reqZone );           
      dateform.setTimeZone(newtz);               // set text formatter for requested time zone
      System.out.println("\nCurrent time in the " 
                        + reqZone 
                        + " zone should be: " 
                        + dateform.format(date) );
      System.out.println( "\nIf this looks wrong, check your OS or network configuration for"
                        + "\n   correct SET LOCALE= and SET TZ= environment settings.");

      // Since there may be other choices at this offset from GMT, here they are
      showLocalZoneOptions(newtz, reqZone);
      System.exit(0); 
   } // end main()

}
/*
 Get my PGP public key from <http://Four11.com>
                         or <http://pgp5.ai.mit.edu/>
                         or any public PGP key server.

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