CronUtils { public static String getCronExpression( String seconds, String minutes, String hours, String days, String months, String weekday ) { return String.join( " ", (seconds == null ? "*" : seconds), (minutes == null ? "*" : minutes), (hours == null ? "*" : hours), (days == null ? "*" : days), (months == null ? "*" : months), (weekday == null ? "*" : weekday) ); }  static String getDailyCronExpression( int minutes, int hours ); static String getWeeklyCronExpression( int minutes, int hours, int dayOfWeek ); static String getMonthlyCronExpression( int minutes, int hours, int dayOfMonth ); static String getCronExpression( String seconds, String minutes, String hours, String days, String months,
        String weekday );  }
@Test public void getCronExpresion() { assertEquals( "1 2 3 4 5 6", CronUtils.getCronExpression( "1", "2", "3", "4", "5", "6" ) ); }