Format a date using the new date time API

Question

LocalDate represents just a date, not a DateTime. So "HH:mm:ss" make no sense when formatting a LocalDate. Use a LocalDateTime instead, assuming you want to represent both a date and time.

I would like to add following details to the correct answer of @James_D:

Background: Most date-and-time-libraries (java.util.Calendar in Java, see also .Net-DateTime or Date in JavaScript or DateTime in Perl) are based on the concept of a universal all-purpose unique temporal type (in German there is the poetic expression "eierlegende Wollmilchsau"). In this design there cannot be an unsupported field. But the price is high: Many time problems cannot be adequately handled with such an unflexible approach because it is hard to impossible to find a common denominator for all kinds of temporal objects.

JSR-310 has choosen another way, namely to allow different temporal types which consist of type-specific sets of supported built-in fields. The natural consequence is that not every possible field is supported by every type (and users can even define their own specialized fields). It is also possible to programmatically ask every object of type TemporalAccessor for its specific set of supported fields. For LocalDate we find:

•DAY_OF_WEEK 
•ALIGNED_DAY_OF_WEEK_IN_MONTH 
•ALIGNED_DAY_OF_WEEK_IN_YEAR 
•DAY_OF_MONTH 
•DAY_OF_YEAR 
•EPOCH_DAY 
•ALIGNED_WEEK_OF_MONTH 
•ALIGNED_WEEK_OF_YEAR 
•MONTH_OF_YEAR 
•PROLEPTIC_MONTH 
•YEAR_OF_ERA 
•YEAR 
•ERA 

There is no HOUR_OF_DAY-field which explains the problem of UnsupportedTemporalTypeException. And if we look at the JSR-310-mapping of pattern symbols to fields we see that the symbol H is mapped to unsupported HOUR_OF_DAY:

/** Map of letters to fields. */  
private static final Map<Character, TemporalField> FIELD_MAP = new HashMap<>();
static {
  FIELD_MAP.put('G', ChronoField.ERA);
  FIELD_MAP.put('y', ChronoField.YEAR_OF_ERA);
  FIELD_MAP.put('u', ChronoField.YEAR);
  FIELD_MAP.put('Q', IsoFields.QUARTER_OF_YEAR);
  FIELD_MAP.put('q', IsoFields.QUARTER_OF_YEAR);
  FIELD_MAP.put('M', ChronoField.MONTH_OF_YEAR);
  FIELD_MAP.put('L', ChronoField.MONTH_OF_YEAR);
  FIELD_MAP.put('D', ChronoField.DAY_OF_YEAR);
  FIELD_MAP.put('d', ChronoField.DAY_OF_MONTH);
  FIELD_MAP.put('F', ChronoField.ALIGNED_DAY_OF_WEEK_IN_MONTH);
  FIELD_MAP.put('E', ChronoField.DAY_OF_WEEK);
  FIELD_MAP.put('c', ChronoField.DAY_OF_WEEK);
  FIELD_MAP.put('e', ChronoField.DAY_OF_WEEK);
  FIELD_MAP.put('a', ChronoField.AMPM_OF_DAY);
  FIELD_MAP.put('H', ChronoField.HOUR_OF_DAY);
  FIELD_MAP.put('k', ChronoField.CLOCK_HOUR_OF_DAY);
  FIELD_MAP.put('K', ChronoField.HOUR_OF_AMPM);
  FIELD_MAP.put('h', ChronoField.CLOCK_HOUR_OF_AMPM);
  FIELD_MAP.put('m', ChronoField.MINUTE_OF_HOUR);
  FIELD_MAP.put('s', ChronoField.SECOND_OF_MINUTE);
  FIELD_MAP.put('S', ChronoField.NANO_OF_SECOND);
  FIELD_MAP.put('A', ChronoField.MILLI_OF_DAY);
  FIELD_MAP.put('n', ChronoField.NANO_OF_SECOND);
  FIELD_MAP.put('N', ChronoField.NANO_OF_DAY);    
}

This field mapping does not mean that the field is supported by the concrete type. Parsing happens in several steps. The field mapping is only the first step. The second step is then parsing to a raw object of type TemporalAccessor. And finally parsing delegates to the target type (here: LocalDate) and let it decide if it accepts all the field values in parsed intermediate object.

The right class for me was ZonedDateTime which includes both Time and Time Zone.

LocalDate doesn't have the Time information so you get a UnsupportedTemporalTypeException: Unsupported field: HourOfDay.

You can use LocalDateTime but then you don't have the Time Zone information so if you try to access that (even by using one of the predefined formatters) you will get a UnsupportedTemporalTypeException: Unsupported field: OffsetSeconds.