How to change the date format of a parameter in Crystal Reports

Use LocalDateTime#parse() (or ZonedDateTime#parse() if the string happens to contain a time zone part) to parse a String in a certain pattern into a LocalDateTime.

String oldstring = "2011-01-18 00:00:00.0";
LocalDateTime datetime = LocalDateTime.parse(oldstring, DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.S"));

Use LocalDateTime#format() (or ZonedDateTime#format()) to format a LocalDateTime into a String in a certain pattern.

String newstring = datetime.format(DateTimeFormatter.ofPattern("yyyy-MM-dd"));
System.out.println(newstring); // 2011-01-18

Or, when you're not on Java 8 yet, use SimpleDateFormat#parse() to parse a String in a certain pattern into a Date.

String oldstring = "2011-01-18 00:00:00.0";
Date date = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.S").parse(oldstring);

Use SimpleDateFormat#format() to format a Date into a String in a certain pattern.

String newstring = new SimpleDateFormat("yyyy-MM-dd").format(date);
System.out.println(newstring); // 2011-01-18

See also:

• Java string to date conversion

Update: as per your failed attempt: the patterns are case sensitive. Read the java.text.SimpleDateFormat javadoc what the individual parts stands for. So stands for example M for months and m for minutes. Also, years exist of four digits yyyy, not five yyyyy. Look closer at the code snippets I posted here above.

What you have looks mostly fine, you just need to apply the comparison logic in the record selection formula instead of in a regular formula. I might also suggest that you create two separate date parameters instead of just using one that has multi-select or ranges.

To get to the record selection formula, Click "Report" in the toolbar → "Selection Formulas" → "Record". From there enter your logic:

({EVENT.DATE} >= {@MinDate} and {EVENT.DATE} <= {@MaxDate})
OR ({CALENDAR.DATE} >= {@MinDate} and {CALENDAR.DATE} <= {@MaxDate})

Alternatively, if you go with two separate parameters, you can do away with the Min/Max formulas:

{EVENT.DATE} in {?Start Date} to {?End Date}
OR {CALENDAR.DATE} in {?Start Date} to {?End Date}