Java 使用/不使用 nanoOfSeconds 将字符串转换为 LocalTime
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Coverting String to LocalTime with/without nanoOfSeconds
提问by jbolt
I need to convert a string to LocalTime (java-8 not joda) that may or maynot have nanoOfSeconds in the string. The String format is in the form of
07:06:05or 07:06:05.123456The string may or may not have a decimal place in the seconds and when it does there could be any number of characters to represent the Nano Seconds part.
我需要将字符串转换为 LocalTime（java-8 不是 joda），字符串中可能有也可能没有 nanoOfSeconds。字符串格式的形式为
07:06:05or07:06:05.123456字符串在秒中可能有也可能没有小数位，当它出现时，可能有任意数量的字符来表示纳米秒部分。
Using a DateTimeForamtter such as
使用 DateTimeFormatter 如
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("H:mm:ss");
or
或者
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("H:mm:ss.SSSSSS");
I can use an IF statement to distinguish between the two formats such as:
我可以使用 IF 语句来区分这两种格式，例如：
DateTimeFormatter dtf;
if (time1.contains(".") {
dtf = DateTimeFormatter.ofPattern("H:mm:ss.SSSSSS);
} else {
dtf = DateTimeFormatter.ofPattern("H:mm:ss);
}
This works fine and I'm OK with this but I need to be able to also use a varying number of positions after the decimal point.
这工作正常，我对此没问题，但我还需要能够在小数点后使用不同数量的位置。
A sample data set might be:
样本数据集可能是：
[11:07:59.68750, 11:08:00.781250, 11:08:00.773437500, 11:08:01]
Is there a way to allow the formatter to parse any number of digits after the decimal without it throwing a java.time.format.DateTimeParseExceptionwhen the number of decimal places is unknown?
有没有办法允许格式化程序解析小数点后任意数量的数字，而不会java.time.format.DateTimeParseException在小数位数未知时抛出 a ？
I'm hoping I missing something really simple.
我希望我错过了一些非常简单的东西。
采纳答案by JodaStephen
There is no need to do anything special to parse this format. LocalTime.parse(String)already handles optional nanoseconds:
不需要做任何特殊的事情来解析这种格式。LocalTime.parse(String)已经处理可选的纳秒：
System.out.println(LocalTime.parse("10:15:30"));
System.out.println(LocalTime.parse("10:15:30."));
System.out.println(LocalTime.parse("10:15:30.1"));
System.out.println(LocalTime.parse("10:15:30.12"));
System.out.println(LocalTime.parse("10:15:30.123456789"));
回答by Jon Skeet
You could use "optional sections" of the format pattern for this:
您可以为此使用格式模式的“可选部分”：
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("H:mm:ss[.SSSSSS]");
