// get user's timezone, configured in the OS.
TimeZone tz = TimeZone.getDefault();

// get a specific timezone.
TimeZone tz = TimeZone.getTimeZone( "UTC" );

// get name e.g. "America/Los_Angeles"
String displayName = tz.getDisplayName();

// offset in millis of Standard Time from GMT. West of the prime meridian is negative.
int rawOffset = tz.getRawOffset();

// offset in millis of Standard time or Daylight time from GMT, depending on which is in effect today.
int offSet = tz.getOffset( new Date().getTime() );

// alternatively get the system property.
String userTZ = System.getProperty( "user.timezone" );