public class PatternWith00Literals {

	private static final Map<String, ChronoFormatter<PlainDate>> PARSERS;

	static {
		Map<String, ChronoFormatter<PlainDate>> parsers = new HashMap<>();
		parsers.put("ddMMyyyy", create("0000yyyy|00MMyyyy|dd00yyyy|ddMMyyyy"));
		parsers.put("MMddyyyy", create("0000yyyy|MM00yyyy|00ddyyyy|MMddyyyy"));
		parsers.put("yyyyMMdd", create("yyyy0000|yyyyMM00|yyyy00dd|yyyyMMdd"));
		PARSERS = Collections.unmodifiableMap(parsers);
	}

	private static ChronoFormatter<PlainDate> create(String pattern) {
		return
			ChronoFormatter.ofDatePattern(pattern, PatternType.CLDR, Locale.ROOT)
			.withDefault(PlainDate.MONTH_AS_NUMBER, 1)
			.withDefault(PlainDate.DAY_OF_MONTH, 1);
	}

	public static void main(String[] args) throws Exception {

		ChronoFormatter<PlainDate> df1 = PARSERS.get("ddMMyyyy");
		System.out.println(df1.parse("04122017")); // 2017-12-04
		System.out.println(df1.parse("00122017")); // 2017-12-01
		System.out.println(df1.parse("04002017")); // 2017-01-04
		System.out.println(df1.parse("00002017")); // 2017-01-01

		ChronoFormatter<PlainDate> df2 = PARSERS.get("MMddyyyy");
		System.out.println(df2.parse("12042017")); // 2017-12-04
		System.out.println(df2.parse("12002017")); // 2017-12-01
		System.out.println(df2.parse("00042017")); // 2017-01-04
		System.out.println(df2.parse("00002017")); // 2017-01-01

		ChronoFormatter<PlainDate> df3 = PARSERS.get("yyyyMMdd");
		System.out.println(df3.parse("20171204")); // 2017-12-04
		System.out.println(df3.parse("20171200")); // 2017-12-01
		System.out.println(df3.parse("20170004")); // 2017-01-04
		System.out.println(df3.parse("20170000")); // 2017-01-01
	}
}