#923 Add helper method to register serializers for java.util.ImmutableCollections (#933)

Author: theigl

src/com/esotericsoftware/kryo/serializers/ImmutableCollectionsSerializers.java

@@ -41,6 +41,15 @@ public static void addDefaultSerializers (Kryo kryo) {
 		}
 	}
 
+	/** Creates new serializers for all types of {@link java.util.ImmutableCollections}s and registers them.
+	 *
+	 * @param kryo the {@link Kryo} instance to register the serializers on. */
+	public static void registerSerializers (Kryo kryo) {
+		JdkImmutableListSerializer.registerSerializers(kryo);
+		JdkImmutableMapSerializer.registerSerializers(kryo);
+		JdkImmutableSetSerializer.registerSerializers(kryo);
+	}
+
 	static class JdkImmutableListSerializer extends CollectionSerializer<List<Object>> {
 
 		private JdkImmutableListSerializer () {
@@ -79,6 +88,14 @@ static void addDefaultSerializers (Kryo kryo) {
 			kryo.addDefaultSerializer(List.of(1, 2, 3, 4).getClass(), serializer);
 			kryo.addDefaultSerializer(List.of(1, 2, 3, 4).subList(0, 2).getClass(), serializer);
 		}
+
+		static void registerSerializers (Kryo kryo) {
+			final JdkImmutableListSerializer serializer = new JdkImmutableListSerializer();
+			kryo.register(List.of().getClass(), serializer);
+			kryo.register(List.of(1).getClass(), serializer);
+			kryo.register(List.of(1, 2, 3, 4).getClass(), serializer);
+			kryo.register(List.of(1, 2, 3, 4).subList(0, 2).getClass(), serializer);
+		}
 	}
 
 	static class JdkImmutableMapSerializer extends MapSerializer<Map<Object, Object>> {
@@ -119,6 +136,13 @@ static void addDefaultSerializers (Kryo kryo) {
 			kryo.addDefaultSerializer(Map.of(1, 2).getClass(), serializer);
 			kryo.addDefaultSerializer(Map.of(1, 2, 3, 4).getClass(), serializer);
 		}
+
+		static void registerSerializers (Kryo kryo) {
+			final JdkImmutableMapSerializer serializer = new JdkImmutableMapSerializer();
+			kryo.register(Map.of().getClass(), serializer);
+			kryo.register(Map.of(1, 2).getClass(), serializer);
+			kryo.register(Map.of(1, 2, 3, 4).getClass(), serializer);
+		}
 	}
 
 	static class JdkImmutableSetSerializer extends CollectionSerializer<Set<Object>> {
@@ -158,6 +182,13 @@ static void addDefaultSerializers (Kryo kryo) {
 			kryo.addDefaultSerializer(Set.of(1).getClass(), serializer);
 			kryo.addDefaultSerializer(Set.of(1, 2, 3, 4).getClass(), serializer);
 		}
+
+		static void registerSerializers (Kryo kryo) {
+			final JdkImmutableSetSerializer serializer = new JdkImmutableSetSerializer();
+			kryo.register(Set.of().getClass(), serializer);
+			kryo.register(Set.of(1).getClass(), serializer);
+			kryo.register(Set.of(1, 2, 3, 4).getClass(), serializer);
+		}
 	}
 
 }

test-jdk11/com/esotericsoftware/kryo/serializers/ImmutableCollectionsSerializersTest.java

@@ -39,13 +39,8 @@ class ImmutableCollectionsSerializersTest extends KryoTestCase {
 	@BeforeEach
 	public void setUp () throws Exception {
 		super.setUp();
-		kryo.register(Class.forName("java.util.ImmutableCollections$List12"));
-		kryo.register(Class.forName("java.util.ImmutableCollections$ListN"));
-		kryo.register(Class.forName("java.util.ImmutableCollections$SubList"));
-		kryo.register(Class.forName("java.util.ImmutableCollections$Map1"));
-		kryo.register(Class.forName("java.util.ImmutableCollections$MapN"));
-		kryo.register(Class.forName("java.util.ImmutableCollections$Set12"));
-		kryo.register(Class.forName("java.util.ImmutableCollections$SetN"));
+		
+		ImmutableCollectionsSerializers.registerSerializers(kryo);
 		kryo.register(HashMap.class);
 		kryo.register(TestClass.class);
 	}