DateTimeFormatter Support for Single Digit Day of Month and Month of Year

Question

DateTimeFormmater doesn\'t seem to handle single digit day of the month:

String format = \"MM/dd/yyyy\";
String date   = \"5/3/1969\";
System.ou         


        

Answer 1

In Java 8 Date Time API, I recently used

DateTimeFormatter formatter = new DateTimeFormatterBuilder()
            .appendOptional(DateTimeFormatter.ofPattern("M/dd/yyyy"))
            .appendOptional(DateTimeFormatter.ofPattern(("MM/dd/yyyy")))
            .toFormatter();

System.out.println(LocalDate.parse("10/22/2020", formatter));
System.out.println(LocalDate.parse("2/21/2020", formatter));

Answer 2

From the documentation:

Number: If the count of letters is one, then the value is output using the minimum number of digits and without padding.

So the format specifier you want is M/d/yyyy, using single letter forms. Of course, it will still parse date Strings like "12/30/1969" correctly as for these day/month values, two digits are the “minimum number of digits”.

The important difference is that MM and dd require zero padding, not that M and d can’t handle values greater than 9 (that would be a bit… unusual).