Implement Comparable interface

Author: ullenius

src/main/java/dev/personnummer/Personnummer.java

@@ -9,7 +9,7 @@
  *
  * @author Johannes Tegnér
  */
-public final class Personnummer {
+public final class Personnummer implements Comparable<Personnummer> {
     private static final Pattern regexPattern;
 
     static {
@@ -241,6 +241,10 @@ public boolean equals(Object obj) {
 		Personnummer other = (Personnummer) obj;
 		return Objects.equals(format(true), other.format(true));
 	}
-    
+
+	@Override
+	public int compareTo(Personnummer other) {
+		return format(true).compareTo(other.format(true));
+	}
 
 }

src/test/java/PersonnummerEqualsHashcode.java

@@ -1,19 +1,25 @@
 import static org.junit.jupiter.api.Assertions.*;
-import org.junit.jupiter.api.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.junit.jupiter.api.*;
 import dev.personnummer.*;
 
 class PersonnummerEqualsHashcode {
-
+	
+	private static final String YOUNG_LONG_FORMAT = "201701022384";
+	
 	@Test
 	void testEquals() throws PersonnummerException {
 
-		assertEquals(new Personnummer("201701022384"), new Personnummer("201701022384"));
-		assertEquals(new Personnummer("201701022384"), new Personnummer("20170102-2384"));
-		assertEquals(new Personnummer("201701022384"), new Personnummer("20170102+2384"));
-		assertEquals(new Personnummer("201701022384"), new Personnummer("170102-2384"));
+		assertEquals(new Personnummer(YOUNG_LONG_FORMAT), new Personnummer(YOUNG_LONG_FORMAT));
+		assertEquals(new Personnummer(YOUNG_LONG_FORMAT), new Personnummer("20170102-2384"));
+		assertEquals(new Personnummer(YOUNG_LONG_FORMAT), new Personnummer("20170102+2384"));
+		assertEquals(new Personnummer(YOUNG_LONG_FORMAT), new Personnummer("170102-2384"));
 
 		assertNotEquals(new Personnummer("170102+2384"), new Personnummer("170102-2384"));
-		assertNotEquals(new Personnummer("201701022384"), new Personnummer("191701022384"));
+		assertNotEquals(new Personnummer(YOUNG_LONG_FORMAT), new Personnummer("191701022384"));
 		assertNotEquals(new Personnummer("20170102-2384"), new Personnummer("19170102-2384"));
 		assertNotEquals(new Personnummer("20170102+2384"), new Personnummer("19170102+2384"));
 
@@ -22,7 +28,7 @@ void testEquals() throws PersonnummerException {
 	@Test
 	void testHashCode() throws PersonnummerException {
 
-		Personnummer young = new Personnummer("201701022384");
+		Personnummer young = new Personnummer(YOUNG_LONG_FORMAT);
 		Personnummer young2 = new Personnummer("1701022384");
 		Personnummer other = new Personnummer("194308239088");
 
@@ -34,9 +40,54 @@ void testHashCode() throws PersonnummerException {
 	@Test
 	void testToString() throws PersonnummerException {
 
-		Personnummer young = new Personnummer("201701022384");
+		Personnummer young = new Personnummer(YOUNG_LONG_FORMAT);
 		assertEquals("170102-2384", young.toString());
 		assertEquals(young.format(), young.toString());
 	}
 
+	@Test
+	void naturalOrderingWorks() throws PersonnummerException {
+		
+		List<Personnummer> numbers = new ArrayList<>();
+		
+		final Personnummer retiree = new Personnummer("194308239088");
+		final Personnummer young = new Personnummer(YOUNG_LONG_FORMAT);
+		final Personnummer centenarian = new Personnummer("170102+2384");
+		
+		
+		numbers.add(retiree);
+		numbers.add(young);
+		numbers.add(centenarian);
+		numbers.add(retiree);
+		assertEquals(4, numbers.size());
+		
+		numbers.sort(null);
+		
+		assertEquals(centenarian, numbers.get(0));
+		assertEquals(retiree, numbers.get(1));
+		assertEquals(retiree, numbers.get(2));
+		assertEquals(young, numbers.get(3));
+	}
+	
+	@Test
+	void testLongFormat() throws PersonnummerException {
+		
+		final Personnummer centenarian = new Personnummer("170102+2384");
+		assertEquals("191701022384", centenarian.format(true));
+	}
+	
+	
+	@Test()
+	void disallowNullValuesForOrdering() throws PersonnummerException {
+		
+		final Personnummer young = new Personnummer(YOUNG_LONG_FORMAT);
+		
+		assertFalse(young.equals(null));
+		assertThrows(NullPointerException.class, () -> {
+			young.compareTo(null);
+		});
+		
+		
+	}
+	
 }