Question

我需要将工作日名称解析为DayOfWeek。周日名称可以是简短（'Mon'）或long（'Monday'）格式。

目前我已经提出了这样的解决方案：

DateTimeFormatter dtf = DateTimeFormatter.ofPattern("EEE", locale);
DayOfWeek dayOfWeek;
try {
    dayOfWeek = DayOfWeek.from(dtf.parse(value));
}
catch (DateTimeException e) {
    dtf = DateTimeFormatter.ofPattern("EEEE", locale);
    dayOfWeek = DayOfWeek.from(dtf.parse(value));
}

是否有更短的解决方案？

Answer 1

您可以将DateTimeFormatterBuilder与可选模式一起使用。这些将按您附加的顺序进行尝试。如果所有模式都失败，仍会抛出DateTimeException。

final DateTimeFormatter dtf = new DateTimeFormatterBuilder()
        .appendOptional(DateTimeFormatter.ofPattern("EEEE"))
        .appendOptional(DateTimeFormatter.ofPattern("E"))
        .toFormatter(locale);

final DayOfWeek dow1 = DayOfWeek.from(dtf.parse("Mon"));
final DayOfWeek dow2 = DayOfWeek.from(dtf.parse("Monday"));

请注意，如果您愿意，结果DayOfWeek现在可以是最终的。

跨多种语言（多个语言环境）尝试相同的代码。

for ( final Locale locale : new Locale[] { Locale.US , Locale.CANADA_FRENCH , Locale.ITALY , Locale.KOREA } ) {
    final String inputShort = ( DayOfWeek.MONDAY.getDisplayName ( TextStyle.SHORT, locale ) );
    final String inputFull = ( DayOfWeek.MONDAY.getDisplayName ( TextStyle.FULL, locale ) );

    final DateTimeFormatter dtf = new DateTimeFormatterBuilder ( )
            .appendOptional ( DateTimeFormatter.ofPattern ( "EEEE" ) )
            .appendOptional ( DateTimeFormatter.ofPattern ( "E" ) )
            .toFormatter ( locale );

    final DayOfWeek dow1 = DayOfWeek.from ( dtf.parse ( inputShort ) ); 
    final DayOfWeek dow2 = DayOfWeek.from ( dtf.parse ( inputFull ) ); 

    System.out.println ( "" );
    System.out.println ( "Language: " + locale.getDisplayLanguage ( Locale.US ) );
    System.out.println ( "inputShort: " + inputShort + " | dow1: " + dow1 );
    System.out.println ( "inputFull: " + inputFull + " | dow2: " + dow2 );
}

跑步时。

Language: English
inputShort: Mon | dow1: MONDAY
inputFull: Monday | dow2: MONDAY

Language: French
inputShort: lun. | dow1: MONDAY
inputFull: lundi | dow2: MONDAY

Language: Italian
inputShort: lun | dow1: MONDAY
inputFull: lunedì | dow2: MONDAY

Locale: Korean
inputShort: 월 | dow1: MONDAY
inputFull: 월요일 | dow2: MONDAY

Answer 2

不要使用try-catch来做条件。 catch是slow。条件更适合if。

final static DateTimeFormatter shortDTF = DateTimeFormatter.ofPattern("EEE", locale);
final static DateTimeFormatter longDTF = DateTimeFormatter.ofPattern("EEEE", locale);

TemporalAccessor parsed; 
try{ 
 if(value.length() > 3){
   parsed = longDTF.parse(value)
 } else {
   parsed = shortDTF.parse(value)  
 }
 dayOfWeek = DayOfWeek.from(parsed);
} catch(DateTimeException e){
  // throw exception here 
}

如果您使用100,000次分析进行性能测试，if语句会更快。

如何用DayOfWeek解析不同模式的工作日名称？

2 个答案: