我正在嘗試使用 java.time.format.DateTimeFormatter 來解析時間字符串，但在解析德語短星期幾名稱時遇到了問題。給定以下程序import java.time.DayOfWeek;import java.time.format.DateTimeFormatter;import java.time.format.DateTimeFormatterBuilder;import java.time.format.TextStyle;import java.util.Locale;var locale = Locale.forLanguageTag("de");var dtf = new DateTimeFormatterBuilder()        .appendOptional(DateTimeFormatter.ofPattern("eeee"))        .appendOptional(DateTimeFormatter.ofPattern("eee"))        .toFormatter(locale);var input1 = DayOfWeek.TUESDAY.getDisplayName(TextStyle.FULL, locale);var input2 = DayOfWeek.TUESDAY.getDisplayName(TextStyle.SHORT_STANDALONE, locale);System.out.printf("input: %s, parsed: %s\n", input1, dtf.parse(input1));System.out.printf("input: %s, parsed: %s\n", input2, dtf.parse(input2));我期望的輸出是input: Dienstag, parsed: {DayOfWeek=2},ISOinput: Di, parsed: {DayOfWeek=2},ISO但我實際上得到input: Dienstag, parsed: {DayOfWeek=2},ISOException in thread "main" java.time.format.DateTimeParseException: Text 'Di' could not be parsed, unparsed text found at index 0    at java.base/java.time.format.DateTimeFormatter.parseResolved0(DateTimeFormatter.java:2049)    at java.base/java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1874)    at org.rksm.Main.main(Main.java:22)請注意，當(dāng)我將語言環(huán)境更改為Locale.forLanguageTag("en")有效時，輸出為input: Tuesday, parsed: {DayOfWeek=2},ISOinput: Tue, parsed: {DayOfWeek=2},ISO我究竟做錯了什么？