enumset without the unuseful set implementation

Author: laurgarn

src/main/java/com/cedarsoftware/util/io/JsonWriter.java

@@ -1091,7 +1091,7 @@ public void writeImpl(Object obj, boolean showType, boolean allowRef, boolean al
         }
         else if (obj instanceof EnumSet)
         {
-            writeEnumSet((EnumSet)obj, showType);
+            writeEnumSet((EnumSet)obj);
         }
         else if (obj instanceof Collection)
         {
@@ -2211,7 +2211,7 @@ else if (neverShowType && MetaUtils.isPrimitive(o.getClass()))
         }
     }
 
-    public void writeEnumSet(final EnumSet<?> enumSet, boolean showType) throws IOException
+    public void writeEnumSet(final EnumSet<?> enumSet) throws IOException
     {
         out.write('{');
         tabIn();
@@ -2224,24 +2224,44 @@ public void writeEnumSet(final EnumSet<?> enumSet, boolean showType) throws IOEx
             newLine();
         }
 
-        if (showType) {
-            writeType(enumSet, out);
-            out.write(",");
-            newLine();
-        }
-
         writeJsonUtf8String("@enum", out);
         out.write(':');
 
+        Enum<? extends Enum<?>> ee = null;
+        if (!enumSet.isEmpty())
+        {
+            ee = enumSet.iterator().next();
+        }
+        else
+        {
+            EnumSet<? extends Enum<?>> complement = EnumSet.complementOf(enumSet);
+            if (!complement.isEmpty())
+            {
+                ee = complement.iterator().next();
+            }
+        }
+
         Field elementTypeField = MetaUtils.getField(EnumSet.class, "elementType");
-        Class elementType = (Class) getValueByReflect(enumSet, elementTypeField);
+        Class<?> elementType = (Class<?>) getValueByReflect(enumSet, elementTypeField);
+        if ( elementType != null)
+        {
+            // nice we got the right to sneak into
+        }
+        else if (ee == null)
+        {
+            elementType = MetaUtils.Dumpty.class;
+        }
+        else
+        {
+            elementType = ee.getClass();
+        }
         writeJsonUtf8String(elementType.getName(), out);
 
-        Map<String, Field> mapOfFileds = MetaUtils.getDeepDeclaredFields(elementType);
-        //Field[] enumFields = elementType.getDeclaredFields();
-        int enumFieldsCount = mapOfFileds.size();
-
         if (!enumSet.isEmpty()) {
+            Map<String, Field> mapOfFields = MetaUtils.getDeepDeclaredFields(elementType);
+            //Field[] enumFields = elementType.getDeclaredFields();
+            int enumFieldsCount = mapOfFields.size();
+
             out.write(",");
             newLine();
 
@@ -2272,7 +2292,7 @@ public void writeEnumSet(final EnumSet<?> enumSet, boolean showType) throws IOEx
                 {
                     boolean firstInEntry = true;
                     out.write('{');
-                    for (Field f : mapOfFileds.values())
+                    for (Field f : mapOfFields.values())
                     {
                         firstInEntry = writeField(e, firstInEntry, f.getName(), f, false);
                     }

src/main/java/com/cedarsoftware/util/io/MetaUtils.java

@@ -36,6 +36,8 @@
  */
 public class MetaUtils
 {
+    public enum Dumpty {}
+
     private MetaUtils () {}
     private static final Map<Class, Map<String, Field>> classMetaCache = new ConcurrentHashMap<>();
     private static final Set<Class> prims = new HashSet<>();

src/main/java/com/cedarsoftware/util/io/Resolver.java

@@ -313,13 +313,21 @@ protected Object createJavaObjectInstance(Class clazz, JsonObject jsonObj)
         String type = jsonObj.type;
 
         // We can't set values to an Object, so well try to use the contained type instead
-		if ("java.lang.Object".equals(type))
+        if ("java.lang.Object".equals(type))
         {
-			Object value = jsonObj.get("value");
-        	if (jsonObj.keySet().size() == 1 && value != null)
+            Object value = jsonObj.get("value");
+            if (jsonObj.keySet().size() == 1 && value != null)
             {
-        		type = value.getClass().getName();
-        	}
+                type = value.getClass().getName();
+            }
+        }
+        if (type == null)
+        {
+            Object mayEnumSpecial = jsonObj.get("@enum");
+            if (mayEnumSpecial instanceof String)
+            {
+                type = "java.util.EnumSet";
+            }
         }
 
         Object mate;
@@ -571,12 +579,24 @@ private Object getEnumSet(Class c, JsonObject<String, Object> jsonObj)
     protected EnumSet<?> extractEnumSet(Class c, JsonObject<String, Object> jsonObj)
     {
         String enumClassName = (String) jsonObj.get("@enum");
-        Class enumClass = MetaUtils.classForName(enumClassName, reader.getClassLoader());
+        Class enumClass = enumClassName == null ? null
+			: MetaUtils.classForName(enumClassName, reader.getClassLoader());
         Object[] items = jsonObj.getArray();
         if (items == null || items.length == 0)
         {
-            return EnumSet.noneOf(enumClass);
+			if (enumClass != null)
+			{
+				return EnumSet.noneOf(enumClass);
+			}
+			else
+			{
+				return EnumSet.noneOf(MetaUtils.Dumpty.class);
+			}
         }
+		else if (enumClass == null)
+		{
+			throw new JsonIoException("Could not figure out Enum of the not empty set " + jsonObj);
+		}
 
         EnumSet enumSet = null;
         for (Object item : items)

src/test/java/com/cedarsoftware/util/io/TestEmptyEnumSetOnJDK17.java

@@ -33,10 +33,12 @@ static class MultiVersioned
     {
         EnumSet<TestEnum> versions;
         String dummy;
+        EnumSet<Thread.State> states;
 
-        public MultiVersioned(EnumSet<TestEnum> versions, String dummy) {
+        public MultiVersioned(EnumSet<TestEnum> versions, String dummy, EnumSet<Thread.State> states) {
             this.versions = versions;
             this.dummy = dummy;
+            this.states = states;
         }
 
         public boolean equals(Object o) {
@@ -76,7 +78,7 @@ public void testEnumSetOnJDK17()
 
     public void testEnumSetInPoJoOnJDK17()
     {
-        MultiVersioned m = new MultiVersioned(EnumSet.of(TestEnum.V1, TestEnum.V3), "what");
+        MultiVersioned m = new MultiVersioned(EnumSet.of(TestEnum.V1, TestEnum.V3), "what", EnumSet.of(Thread.State.NEW));
 
         String json = JsonWriter.objectToJson(m);
         MultiVersioned target = (MultiVersioned) JsonReader.jsonToJava(json);