A DESCRIPTION OF THE PROBLEM :
At JDK-8042131, the behaivor of DateTimeformatter.format was fixed.
However, parse method is still wrong.

I guess the anonymouse class in DateTimeFormatterBuilder.appendText(TemporalField field, Map<Long, String> textLookup) should override getTextIterator(TemporalField field, TextStyle style, Locale locale) too.


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Compile and run the test case.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
{Era=2, YearOfEra=1, MonthOfYear=4},Japanese
ACTUAL -
Exception in thread "main" java.time.format.DateTimeParseException: Text 'Heisei 1st-4gatsu' could not be parsed at index 8
at java.base/java.time.format.DateTimeFormatter.parseResolved0(DateTimeFormatter.java:2046)
at java.base/java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1874)
at FormatterBuilderTest_ja_jp.main(FormatterBuilderTest_ja_jp.java:26)

---------- BEGIN SOURCE ----------

import java.util.*;
import java.time.format.*;
import java.time.temporal.*;
import java.time.chrono.*;

public class FormatterBuilderTest_ja_jp {

    public static void main(String[] args) {
        Map<Long, String> years = Map.of(1L, "1st");
        Map<Long, String> monthes = new HashMap<>();
        for (long l = 1; l <= 12; l++) {
            monthes.put(l, l + "gatsu");
        }
        DateTimeFormatterBuilder builder = new DateTimeFormatterBuilder()
                .appendText(ChronoField.ERA, TextStyle.FULL)
                .appendLiteral(' ')
                .appendText(ChronoField.YEAR_OF_ERA, years)
                .appendLiteral('-')
                .appendText(ChronoField.MONTH_OF_YEAR, monthes);

        DateTimeFormatter formatter = builder.toFormatter(Locale.US)
                .withChronology(JapaneseChronology.INSTANCE);

// System.out.println(formatter.parse("Heisei 1-April"));
        System.out.println(formatter.parse("Heisei 1st-4gatsu"));
    }
}

---------- END SOURCE ----------

FREQUENCY : always