Simplify usage

README.md

@@ -36,20 +36,18 @@ NB: To find the latest version, please refer to [Maven search](https://search.ma
 
 ### Quickstart
 
-- To convert a Gregorian (usual) date into a Republican date:
+- To convert a Gregorian local date into a Republican date:
 
 ```java
-GRConverter c = new GRConverter();
 LocalDate date = LocalDate.of(1792, 9, 22);
-RDate rDate = c.convert(date);
+RDate rDate = RDate.of(localDate);
 ```
 
 - To convert a Republican date into a Gregorian date:
 
 ```java
-RGConverter c = new RGConverter();
 RDate rDate = RDate.of(1, RMonth.Vendemiaire, 1);
-LocalDate date = c.convert(rDate);
+LocalDate date = c.toLocalDate();
 ```
 
 - `RDate` represents a Republican date and provides some utility methods:

src/main/java/com/github/jarnaud/republican/GRConverter.java

@@ -7,7 +7,7 @@
 /**
  * Converter from Gregorian to Republican dates.
  */
-public class GRConverter {
+class GRConverter {
 
     /**
      * Officially the Republican calendar started on 1792-09-22 (An I Vendemiaire 1).

src/main/java/com/github/jarnaud/republican/LeapYearCalculator.java

@@ -3,7 +3,7 @@
 /**
  * Process the number of leap years between the start of the Republican calendar and a given year.
  */
-public class LeapYearCalculator {
+class LeapYearCalculator {
 
     private static final int START_REPUBLICAN_YEAR = 1792;
 

src/main/java/com/github/jarnaud/republican/RDate.java

@@ -70,10 +70,31 @@ public static RDate of(int year, int month, int day) {
         return new RDate(year, RMonth.values()[month - 1], day);
     }
 
+    /**
+     * Construct a new Republican date from a Gregorian date.
+     * Throws a RuntimeException if the given date is invalid (ie. before first day of Republican calendar).
+     *
+     * @param date the Gregorian date.
+     * @return the Republican date.
+     */
+    public static RDate of(LocalDate date) {
+        return new GRConverter().convert(date);
+    }
+
+    /**
+     * Return the Republican year for this date.
+     *
+     * @return the year.
+     */
     public int getYear() {
         return year;
     }
 
+    /**
+     * Return the Republican month for this date.
+     *
+     * @return the month.
+     */
     public RMonth getMonth() {
         return month;
     }
@@ -90,6 +111,11 @@ public int getDecade() {
         return decade;
     }
 
+    /**
+     * Return the day of the month of this date.
+     *
+     * @return the day of the month.
+     */
     public int getDay() {
         return day;
     }
@@ -132,6 +158,15 @@ public int hashCode() {
         return Objects.hash(year, month, decade, day);
     }
 
+    /**
+     * Convert this Republican date into a Gregorian local date.
+     *
+     * @return the local date.
+     */
+    public LocalDate toLocalDate() {
+        return new RGConverter().convert(this);
+    }
+
     /**
      * Return true if the given date is strictly before this date.
      *

src/main/java/com/github/jarnaud/republican/RGConverter.java

@@ -6,7 +6,7 @@
 /**
  * Converter from Republican to Gregorian dates.
  */
-public class RGConverter {
+class RGConverter {
 
     /**
      * Officially the Republican calendar started on 1792-09-22 (An I Vendemiaire 1).

src/main/java/com/github/jarnaud/republican/RMonth.java

@@ -39,7 +39,7 @@ public enum RMonth {
     /**
      * Return the month number (eg. 1 for Vendemiaire, 12 for Fructidor, 13 for Sanculottide...)
      *
-     * @return the month number.
+     * @return the month number, between 1 and 13.
      */
     public int getMonth() {
         return month;

src/test/java/com/github/jarnaud/republican/ConverterTest.java

@@ -183,6 +183,19 @@ private void compare(int rYear, RMonth rMonth, int rDay, int gYear, int gMonth,
                 LocalDate.of(gYear, gMonth, gDay),
                 rgConverter.convert(RDate.of(rYear, rMonth, rDay))
         );
+
+        // Test RDate methods:
+
+        assertEquals(
+                RDate.of(rYear, rMonth, rDay),
+                RDate.of(LocalDate.of(gYear, gMonth, gDay))
+        );
+
+        assertEquals(
+                LocalDate.of(gYear, gMonth, gDay),
+                RDate.of(rYear, rMonth, rDay).toLocalDate()
+        );
+
     }
 
 }

src/test/java/com/github/jarnaud/republican/RDateTest.java

@@ -2,6 +2,8 @@
 
 import org.junit.jupiter.api.Test;
 
+import java.time.LocalDate;
+
 import static org.junit.jupiter.api.Assertions.*;
 
 public class RDateTest {
@@ -21,6 +23,12 @@ public void testOf2() {
         assertEquals(RDate.of(58, RMonth.Floreal, 1), RDate.of(58, 8, 1));
     }
 
+    @Test
+    public void testOf3() {
+        assertThrows(RuntimeException.class, () -> RDate.of(LocalDate.of(1650, 1, 1)));
+        // Normal cases are handled by the converter test.
+    }
+
     @Test
     public void testDecade() {
         assertEquals(1, RDate.of(6, RMonth.Floreal, 1).getDecade());
@@ -34,6 +42,14 @@ public void testDecade() {
         assertEquals(3, RDate.of(6, RMonth.Floreal, 30).getDecade());
     }
 
+    @Test
+    public void testEquals_symmetric() {
+        RDate rd1 = RDate.of(12, RMonth.Brumaire, 18);
+        RDate rd2 = RDate.of(12, 2, 18);
+        assertEquals(rd1, rd2);
+        assertEquals(rd2.hashCode(), rd1.hashCode());
+    }
+
     @Test
     public void testIsBefore() {
         RDate d1 = RDate.of(6, RMonth.Floreal, 4);