Question

我有一个ggplot(data, aes(x = value)) + geom_histogram(color = "red", stat = StatBin2) + # specify stat = StatBin2 facet_wrap(~ key, ncol = 1)日期。此日期为西方日期格式。我想要的是日文格式。

String

当前错误：

String a = "2019-05-10";
DateTimeFormatter timeFormatter = new DateTimeFormatterBuilder()
            .appendPattern("YYYY-MM-DD")
            .toFormatter(Locale.JAPAN);
String aa = LocalTime.parse(a, timeFormatter)
            .format(DateTimeFormatter.ofPattern("YYYY年MM月DD日", Locale.JAPAN));

System.out.println(aa);

预期输出：

Exception in thread "main" java.time.format.DateTimeParseException: Text '2019-05-10' could not be parsed: Unable to obtain LocalTime from TemporalAccessor: {DayOfYear=10, MonthOfYear=5, WeekBasedYear[WeekFields[SUNDAY,1]]=2019},ISO of type java.time.format.Parsed
    at java.time.format.DateTimeFormatter.createError(Unknown Source)
    at java.time.format.DateTimeFormatter.parse(Unknown Source)
    at java.time.LocalTime.parse(Unknown Source)
    at testing.DatumTypeDecimal.main(DatumTypeDecimal.java:223)
Caused by: java.time.DateTimeException: Unable to obtain LocalTime from TemporalAccessor: {DayOfYear=10, MonthOfYear=5, WeekBasedYear[WeekFields[SUNDAY,1]]=2019},ISO of type java.time.format.Parsed
    at java.time.LocalTime.from(Unknown Source)
    at java.time.format.Parsed.query(Unknown Source)
    ... 3 more

Answer 1

好的，这需要一些步骤...

首先，将输入内容输入有效的日期容器（即threshold = 0.5 prediction=np.array([0,0.2,0.9,0.7]) prediction[prediction<=threshold]=0 prediction[prediction>threshold]=1）

LocalDate

接下来，构造一个日期格式化程序，它将能够将日期容器格式化为我们想要的格式。请注意，我使用String input = "2019-05-10"; DateTimeFormatter inputFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd"); LocalDate localDate = LocalDate.parse(input, inputFormatter);而不是提供模式，因为它可以产生更好的结果

DateTimeFormatter.ofLocalizedDate(FormatStyle.FULL)

最后，格式化日期容器...

DateTimeFormatter outputFormatter = new DateTimeFormatterBuilder()
        .append(DateTimeFormatter.ofLocalizedDate(FormatStyle.FULL))
//                .appendPattern("yyyy年MM月dd日")
        .toFormatter(Locale.JAPAN);

这将生成String output = outputFormatter.format(localDate); System.out.println(output);

此外，2019年5月10日金曜日生成的FormatStye.LONG似乎更符合您的目标异常

Answer 2

对于日期，您应该使用适当的类，而不是LocalTime，而是LocalDate。另外，由于大写Y和D，您的模式是错误的。

我已经通过以下方式尝试过：

public static void main(String args[]) throws Exception {
    String a = "2019-05-10";    // ISO date format
    String b = "2019-5-10";     // date format with only a single digit for month
    LocalDate ldA = LocalDate.parse(a, DateTimeFormatter.ISO_DATE);
    LocalDate ldB = LocalDate.parse(b, DateTimeFormatter.ofPattern("yyyy-M-dd"));
    // note the lower case year and day, month stays upper case
    System.out.println(ldA.format(DateTimeFormatter.ofPattern("yyyy年MM月dd日", Locale.JAPAN)));
    System.out.println(ldB.format(DateTimeFormatter.ofPattern("yyyy年MM月dd日", Locale.JAPAN)));
}

然后输出

2019年05月10日

要将其存储在String中，只需执行

String myJapaneseDate = ldA.format(DateTimeFormatter.ofPattern("yyyy年MM月dd日", Locale.JAPAN));

编辑：

根据要求，下面是一个示例方法，该方法用于（1）使给定的String为有效的ISO格式，并且（2）返回从中解析出的LocalDate。

public static void main(String args[]) throws Exception {
    String a = "2019-05-10";    // ISO date format
    String b = "2019-5-10";     // date format with only a single digit for month
    LocalDate ldA = makeItIsoFormat(a);
    LocalDate ldB = makeItIsoFormat(b);
    // note the lower case year and day, month stays upper case
    System.out.println(ldA.format(DateTimeFormatter.ofPattern("yyyy年MM月dd日", Locale.JAPAN)));
    System.out.println(ldB.format(DateTimeFormatter.ofPattern("yyyy年MM月dd日", Locale.JAPAN)));
}

public static LocalDate makeItIsoFormat(String date) {
    // first, split the input String by a hyphon
    String[] splitDate = date.split("-");

    // check its length, it has to have 3 parts (year, month, day)
    if (splitDate.length != 3) {
        // if it has more or less parts, the date is considered invalid
        System.err.println("invalid date String provided");
    } else {
        // otherwise, check the amount of digits it has for month
        if (splitDate[1].length() == 1) {
            // and if it is just one, add a leading zero
            System.out.println("The given date \"" 
                    + date 
                    + "\" has a single digit for month, add leading zero");
            splitDate[1] = "0" + splitDate[1];
        }
    }

    /*
     * CONSIDER ADDING A CHECK FOR SINGLE-DIGIT DAYS, it is not yet included
     */

    // recreate the date String
    String isoDate = splitDate[0] + "-" + splitDate[1] + "-" + splitDate[2];
    // and return the parsed LocalDate
    return LocalDate.parse(isoDate, DateTimeFormatter.ISO_DATE);
}

Answer 3

我不知道其他解决方案，但是希望这段代码对您有所帮助。该方法仅替换字符'-'，然后替换append()最后一个字符。

public String japaneseFormat(String date){
   StringBuilder date =new StringBuilder(date);

   date.setCharAt(4,'年'); 
   date.setCharAt(7,'月');
   date.append("日");
   return date.toString();
}

Answer 4

你可以用 2 个 SimpleDateFormat

示例：

String input = "2019-05-10";
Date date = new SimpleDateFormat("yyyy-MM-dd").parse(input);
System.out.println(new SimpleDateFormat("yyyy年MM月dd日").format(date));

输出：

2019年05月10日

怎么把西方日期格式转换成日本日期格式？

4 个答案: