从 LocalDateTime.parse 缺少第二（00）

Question

missing second (00) from LocalDateTime.parse

LocalTime time = LocalTime.NOON;
DateTimeFormatter formatTime = DateTimeFormatter.ofPattern("HH:mm:ss");
String value ="20200810" + time.format(formatTime);
LocalDateTime localDateTime = LocalDateTime.parse(value, DateTimeFormatter.ofPattern("yyyyMMddHH:mm:ss"));

LOGS

=========value========== 2020081012:00:00
===localDateTime===2020-08-10T**12:00**

I tried to change LocalTime.NOON to LocalTime.of(12,0,0) too but still same result.

Answer 1

Write the following line into log:

localDateTime.format(DateTimeFormatter.ISO_LOCAL_DATE_TIME)

The above line returns a string as per DateTimeFormatter.ISO_LOCAL_DATE_TIME .

You can also specify a custom pattern as per your requirement eg

localDateTime.format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"))

or

localDateTime.format(DateTimeFormatter.ofPattern("yyyyMMddHH:mm:ss"))

If you print localDateTime directly, it will print the string returned by toString method of LocalDateTime .

Note that since the second part in the time, 12:00:00 is 00 , the default toString implementation of LocalDateTime ignores the second part.

For your reference, given below is the toString() implementation of LocalDateTime :

@Override
public String toString() {
    return date.toString() + 'T' + time.toString();
}

and given below the toString() implementation of LocalTime :

@Override
public String toString() {
    StringBuilder buf = new StringBuilder(18);
    int hourValue = hour;
    int minuteValue = minute;
    int secondValue = second;
    int nanoValue = nano;
    buf.append(hourValue < 10 ? "0" : "").append(hourValue)
        .append(minuteValue < 10 ? ":0" : ":").append(minuteValue);
    if (secondValue > 0 || nanoValue > 0) {
        buf.append(secondValue < 10 ? ":0" : ":").append(secondValue);
        if (nanoValue > 0) {
            buf.append('.');
            if (nanoValue % 1000_000 == 0) {
                buf.append(Integer.toString((nanoValue / 1000_000) + 1000).substring(1));
            } else if (nanoValue % 1000 == 0) {
                buf.append(Integer.toString((nanoValue / 1000) + 1000_000).substring(1));
            } else {
                buf.append(Integer.toString((nanoValue) + 1000_000_000).substring(1));
            }
        }
    }
    return buf.toString();
}

As you can see, the second and nano parts are included only when their values are greater than 0 .