utilize DateTimeFormatter for parsing of incomplete dates

histream-core/src/main/java/de/sekmi/histream/DateTimeAccuracy.java

 package de.sekmi.histream;
 
+import java.time.DateTimeException;
+
 /*
  * #%L
  * histream
@@ -22,9 +24,11 @@ package de.sekmi.histream;
 
 
 import java.time.LocalDateTime;
+import java.time.format.DateTimeFormatter;
 import java.time.temporal.ChronoField;
 import java.time.temporal.ChronoUnit;
 import java.time.temporal.Temporal;
+import java.time.temporal.TemporalAccessor;
 import java.time.temporal.TemporalField;
 import java.time.temporal.TemporalUnit;
 import java.util.Date;
@@ -230,4 +234,54 @@ public class DateTimeAccuracy implements Temporal {
 		}
 		throw new UnsupportedOperationException("Timezone support not implemented yet");
 	}
+	
+	/**
+	 * Parse date time with a formatter.
+	 * 
+	 * @param formatter formatter
+	 * @param text input text
+	 * @return date time with accuracy
+	 */
+	public static DateTimeAccuracy parse(DateTimeFormatter formatter, CharSequence text){
+		TemporalAccessor a = formatter.parse(text);
+		int year = a.get(ChronoField.YEAR);
+		// month
+		int month;
+		try{
+			month = a.get(ChronoField.MONTH_OF_YEAR);
+		}catch( DateTimeException e ){
+			return new DateTimeAccuracy(year);
+		}
+		
+		int day;
+		try{
+			day = a.get(ChronoField.DAY_OF_MONTH);
+		}catch( DateTimeException e ){
+			return new DateTimeAccuracy(year,month);
+		}
+
+		int hour;
+		try{
+			hour = a.get(ChronoField.HOUR_OF_DAY);
+		}catch( DateTimeException e ){
+			return new DateTimeAccuracy(year,month,day);
+		}
+
+		int minute;
+		try{
+			minute = a.get(ChronoField.MINUTE_OF_HOUR);
+		}catch( DateTimeException e ){
+			return new DateTimeAccuracy(year,month,day, hour);
+		}
+		
+		int seconds;
+		try{
+			seconds = a.get(ChronoField.SECOND_OF_MINUTE);
+		}catch( DateTimeException e ){
+			return new DateTimeAccuracy(year,month,day, hour, minute);
+		}
+
+		return new DateTimeAccuracy(year,month,day, hour, minute, seconds);
+		// milliseconds not supported for now
+	}
 }

histream-core/src/test/java/de/sekmi/histream/TestDateTimeAccuracy.java

+package de.sekmi.histream;
+
+import java.text.ParsePosition;
+import java.time.format.DateTimeFormatter;
+import java.time.temporal.ChronoField;
+import java.time.temporal.ChronoUnit;
+import java.time.temporal.TemporalAccessor;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class TestDateTimeAccuracy {
+
+	@Test
+	public void testParseYYYYDD(){
+		//DateTimeAccuracy a = DateTimeAccuracy.parse(formatter, text)
+		DateTimeFormatter formatter = DateTimeFormatter.ofPattern("M.u");
+		String text = "02.2003";
+		DateTimeAccuracy a = DateTimeAccuracy.parse(formatter, text);
+		Assert.assertEquals(ChronoUnit.MONTHS,a.getAccuracy());
+		Assert.assertEquals(2, a.get(ChronoField.MONTH_OF_YEAR));
+		Assert.assertEquals(2003, a.get(ChronoField.YEAR));
+	}
+	// TODO: further tests
+}