Example usage for com.google.gson TypeAdapter fromJsonTree

List of usage examples for com.google.gson TypeAdapter fromJsonTree

Introduction

In this page you can find the example usage for com.google.gson TypeAdapter fromJsonTree.

Prototype

public final T fromJsonTree(JsonElement jsonTree) 

Source Link

Document

Converts jsonTree to a Java object.

Usage

From source file:com.truethat.android.external.gson.RuntimeTypeAdapterFactory.java

License:Apache License

/**
 * This method was modified, to include {@link #typeFieldName} in serialized registered sub types.
 *///from   w w w.  j av  a 2s .c  o m
@Nullable
public <R> TypeAdapter<R> create(Gson gson, TypeToken<R> type) {
    if (type.getRawType() != baseType && !labelToSubtype.containsKey(type.getRawType().getSimpleName())) {
        return null;
    }

    final Map<String, TypeAdapter<?>> labelToDelegate = new LinkedHashMap<>();
    final Map<Class<?>, TypeAdapter<?>> subtypeToDelegate = new LinkedHashMap<>();
    for (Map.Entry<String, Class<?>> entry : labelToSubtype.entrySet()) {
        TypeAdapter<?> delegate = gson.getDelegateAdapter(this, TypeToken.get(entry.getValue()));
        labelToDelegate.put(entry.getKey(), delegate);
        subtypeToDelegate.put(entry.getValue(), delegate);
    }

    return new TypeAdapter<R>() {
        @Override
        public void write(JsonWriter out, R value) throws IOException {
            Class<?> srcType = value.getClass();
            String label = subtypeToLabel.get(srcType);
            @SuppressWarnings("unchecked") // registration requires that subtype extends T
            TypeAdapter<R> delegate = (TypeAdapter<R>) subtypeToDelegate.get(srcType);
            if (delegate == null) {
                throw new JsonParseException(
                        "cannot serialize " + srcType.getName() + "; did you forget to register a subtype?");
            }
            JsonObject jsonObject = delegate.toJsonTree(value).getAsJsonObject();
            if (jsonObject.has(typeFieldName)) {
                throw new JsonParseException("cannot serialize " + srcType.getName()
                        + " because it already defines a field named " + typeFieldName);
            }
            JsonObject clone = new JsonObject();
            clone.add(typeFieldName, new JsonPrimitive(label));
            for (Map.Entry<String, JsonElement> e : jsonObject.entrySet()) {
                clone.add(e.getKey(), e.getValue());
            }
            Streams.write(clone, out);
        }

        @Override
        public R read(JsonReader in) throws IOException {
            JsonElement jsonElement = Streams.parse(in);
            JsonElement labelJsonElement = jsonElement.getAsJsonObject().remove(typeFieldName);
            if (labelJsonElement == null) {
                throw new JsonParseException("cannot deserialize " + baseType
                        + " because it does not define a field named " + typeFieldName);
            }
            String label = labelJsonElement.getAsString();
            @SuppressWarnings("unchecked") // registration requires that subtype extends T
            TypeAdapter<R> delegate = (TypeAdapter<R>) labelToDelegate.get(label);
            if (delegate == null) {
                throw new JsonParseException("cannot deserialize " + baseType + " subtype named " + label
                        + "; did you forget to register a subtype?");
            }
            return delegate.fromJsonTree(jsonElement);
        }
    }.nullSafe();
}

From source file:com.vaadin.addon.charts.model.gsonhelpers.AbstractSeriesTypeAdapterFactory.java

private TypeAdapter<AbstractSeries> customizeMyClassAdapter(Gson gson, TypeToken<AbstractSeries> type) {
    final TypeAdapter<AbstractSeries> delegate = gson.getDelegateAdapter(this, type);
    final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
    return new TypeAdapter<AbstractSeries>() {
        @Override/*from  w  w w.  j  a v  a 2 s  .c  o m*/
        public void write(JsonWriter out, AbstractSeries value) throws IOException {
            JsonObject tree = (JsonObject) delegate.toJsonTree(value);

            // "flatten" series specific plot options at series level. see
            // Higchart API for details
            if (value.getPlotOptions() != null) {
                JsonObject plotOptionsJson = (JsonObject) tree.remove("plotOptions");
                if (plotOptionsJson != null) {
                    Set<Entry<String, JsonElement>> entrySet = plotOptionsJson.entrySet();
                    for (Entry<String, JsonElement> entry : entrySet) {
                        tree.add(entry.getKey(), entry.getValue());
                    }
                    tree.addProperty("type", value.getPlotOptions().getChartType().toString());
                }
            }
            elementAdapter.write(out, tree);
        }

        // This is never used
        @Override
        public AbstractSeries read(JsonReader in) throws IOException {
            JsonElement tree = elementAdapter.read(in);
            return delegate.fromJsonTree(tree);
        }
    };
}

From source file:com.vaadin.addon.charts.model.gsonhelpers.DataSeriesItemTypeAdapterFactory.java

private TypeAdapter<DataSeriesItem> customizeMyClassAdapter(Gson gson, TypeToken<DataSeriesItem> type) {
    final TypeAdapter<DataSeriesItem> delegate = gson.getDelegateAdapter(this, type);
    final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
    return new TypeAdapter<DataSeriesItem>() {
        @Override/*from  www. j av  a 2s .co  m*/
        public void write(JsonWriter out, DataSeriesItem value) throws IOException {
            if (value.isCustomized()) {
                elementAdapter.write(out, delegate.toJsonTree(value));
            } else {
                Number x = value.getX();
                Number y = value.getY();
                if (x != null) {
                    JsonArray jsonArray = new JsonArray();
                    jsonArray.add(new JsonPrimitive(x));
                    if (y != null) {
                        jsonArray.add(new JsonPrimitive(y));
                    } else if (value.getLow() != null) {
                        jsonArray.add(new JsonPrimitive(value.getLow()));
                        jsonArray.add(new JsonPrimitive(value.getHigh()));
                    } else {
                        jsonArray.add(JsonNull.INSTANCE);
                        jsonArray.add(JsonNull.INSTANCE);
                    }
                    elementAdapter.write(out, jsonArray);
                } else {
                    // If no x set, make it like list series, just number or
                    // min-max pairs
                    if (y != null) {
                        elementAdapter.write(out, new JsonPrimitive(y));
                    } else {
                        JsonArray jsonArray = new JsonArray();
                        jsonArray.add(new JsonPrimitive(value.getLow()));
                        jsonArray.add(new JsonPrimitive(value.getHigh()));
                        elementAdapter.write(out, jsonArray);
                    }
                }
            }
        }

        // This is never used
        @Override
        public DataSeriesItem read(JsonReader in) throws IOException {
            JsonElement tree = elementAdapter.read(in);
            return delegate.fromJsonTree(tree);
        }
    };
}

From source file:com.vaadin.addon.charts.model.gsonhelpers.TitleTypeAdapterFactory.java

private TypeAdapter<Title> customizeMyClassAdapter(Gson gson, TypeToken<Title> type) {
    final TypeAdapter<Title> delegate = gson.getDelegateAdapter(this, type);
    final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
    return new TypeAdapter<Title>() {
        @Override/*from www .  j av a  2 s .c  o m*/
        public void write(JsonWriter out, Title value) throws IOException {
            // null for text is significant, else there will be
            // "Chart Title" as default
            if (value != null && value.getText() == null) {
                boolean serializeNulls = out.getSerializeNulls();
                out.setSerializeNulls(true);
                out.beginObject();
                out.name("text");
                out.nullValue();
                out.endObject();
                out.setSerializeNulls(serializeNulls);
            } else {
                elementAdapter.write(out, delegate.toJsonTree(value));
            }
        }

        // This is never used
        @Override
        public Title read(JsonReader in) throws IOException {
            JsonElement tree = elementAdapter.read(in);
            return delegate.fromJsonTree(tree);
        }
    };
}

From source file:com.wix.mediaplatform.gson.RuntimeTypeAdapterFactory.java

License:Apache License

public <R> TypeAdapter<R> create(Gson gson, TypeToken<R> type) {
    if (null == type || !baseType.isAssignableFrom(type.getRawType())) {
        return null;
    }//from  ww  w.  j  a  va  2  s .co m

    final Map<String, TypeAdapter<?>> labelToDelegate = new LinkedHashMap<>();
    final Map<Class<?>, TypeAdapter<?>> subtypeToDelegate = new LinkedHashMap<>();
    for (Map.Entry<String, Class<?>> entry : labelToSubtype.entrySet()) {
        TypeAdapter<?> delegate = gson.getDelegateAdapter(this, TypeToken.get(entry.getValue()));
        labelToDelegate.put(entry.getKey(), delegate);
        subtypeToDelegate.put(entry.getValue(), delegate);
    }

    return new TypeAdapter<R>() {
        @Override
        public R read(JsonReader in) throws IOException {
            JsonElement jsonElement = Streams.parse(in);
            JsonElement labelJsonElement = jsonElement.getAsJsonObject().get(typeFieldName);
            if (labelJsonElement == null) {
                throw new JsonParseException("cannot deserialize " + baseType
                        + " because it does not define a field named " + typeFieldName);
            }
            String label = labelJsonElement.getAsString();
            @SuppressWarnings("unchecked") // registration requires that subtype extends T
            TypeAdapter<R> delegate = (TypeAdapter<R>) labelToDelegate.get(label);
            if (delegate == null) {
                throw new JsonParseException("cannot deserialize " + baseType + " subtype named " + label
                        + "; did you forget to register a subtype?");
            }
            return delegate.fromJsonTree(jsonElement);
        }

        @Override
        public void write(JsonWriter out, R value) throws IOException {
            Class<?> srcType = value.getClass();
            String label = subtypeToLabel.get(srcType);
            @SuppressWarnings("unchecked") // registration requires that subtype extends T
            TypeAdapter<R> delegate = (TypeAdapter<R>) subtypeToDelegate.get(srcType);
            if (delegate == null) {
                throw new JsonParseException(
                        "cannot serialize " + srcType.getName() + "; did you forget to register a subtype?");
            }
            JsonObject jsonObject = delegate.toJsonTree(value).getAsJsonObject();
            //                if (jsonObject.has(typeFieldName)) {
            //                    throw new JsonParseException("cannot serialize " + srcType.getName()
            //                            + " because it already defines a field named " + typeFieldName);
            //                }
            JsonObject clone = new JsonObject();
            //                clone.add(typeFieldName, new JsonPrimitive(label));
            for (Map.Entry<String, JsonElement> e : jsonObject.entrySet()) {
                clone.add(e.getKey(), e.getValue());
            }
            Streams.write(clone, out);
        }
    }.nullSafe();
}

From source file:com.xpbytes.gson.hal.HalTypeAdapterFactory.java

License:Apache License

@Override
public <T> TypeAdapter<T> create(final Gson gson, final TypeToken<T> type) {

    final TypeAdapter<T> delegate = gson.getDelegateAdapter(this, type);
    final TypeAdapter<JsonElement> basicAdapter = gson.getAdapter(JsonElement.class);
    // If we convert to JSON, isn't the deserializer more appropriate...?

    // Is this a HalResource?
    if (!HalReflection.isResource(type.getRawType()))
        return delegate;

    return new TypeAdapter<T>() {
        @Override//  w w  w .j a v  a 2s  .c o m
        public void write(JsonWriter out, T value) throws IOException {
            delegate.write(out, value);
        }

        @Override
        public T read(JsonReader in) throws IOException {
            JsonElement fullJson = basicAdapter.read(in);
            Logger.getGlobal().log(Level.ALL, fullJson.toString());
            T deserialized = delegate.fromJsonTree(fullJson);

            if (fullJson.isJsonObject()) {
                JsonObject fullJsonObject = fullJson.getAsJsonObject();

                JsonObject linksObject = fullJsonObject.getAsJsonObject(HalConstants.RESERVED_LINKS_ROOT);
                JsonObject embeddedObject = fullJsonObject.getAsJsonObject(HalConstants.RESERVED_EMBEDDED_ROOT);

                List<Field> fieldsList = HalReflection.getHalFields(type.getRawType());
                for (Field field : fieldsList) {
                    if (HalReflection.isLink(field))
                        readLink(field, linksObject, deserialized);
                    else if (HalReflection.isEmbed(field))
                        readEmbed(field, embeddedObject, deserialized);
                }

            }

            return deserialized;
        }

        private <A> void readEmbed(Field field, JsonObject rootObject, A deserialized) {
            HalEmbed embed = field.getAnnotation(HalEmbed.class);
            boolean optional = embed.optional();
            if (rootObject == null && optional)
                return;

            String memberName = HalReflection.getJsonFieldName(embed, field);
            JsonParseException missingException = new JsonParseException(
                    String.format(Locale.US, "Expected embed `%s` in the embedded root `%s` to be present",
                            memberName, HalConstants.RESERVED_EMBEDDED_ROOT));

            if (rootObject == null)
                throw missingException;

            boolean exists = rootObject.has(memberName);
            if (!exists) {
                if (optional)
                    return;
                throw missingException;
            }

            Type innerType = HalReflection.getFieldItemizedType(field);
            //Class outerType = HalReflection.getFieldType( field );
            JsonElement element = rootObject.get(memberName);

            // This gson.fromJson call will actually call into the proper stack to recursively
            // deserialize embeds and set their links where necessary.
            HalReflection.setEmbed(field, gson.fromJson(element, innerType), deserialized);
        }

        private <A> void readLink(Field field, JsonObject rootObject, A deserialized) {

            HalLink link = field.getAnnotation(HalLink.class);
            boolean optional = link.optional();
            if (rootObject == null && optional)
                return;

            String memberName = HalReflection.getJsonFieldName(link, field);
            JsonParseException missingException = new JsonParseException(
                    String.format(Locale.US, "Expected link `%s` in the links root `%s` to be present",
                            memberName, HalConstants.RESERVED_LINKS_ROOT));

            if (rootObject == null)
                throw missingException;

            boolean exists = rootObject.has(memberName);
            if (!exists) {
                if (optional)
                    return;
                throw missingException;
            }

            // If this is not a descendant of a HalLinkObject, we better treat it as one.
            Class<?> innerType = HalReflection.getFieldItemizedType(field);
            if (!innerType.isAssignableFrom(HalLinkObject.class))
                innerType = HalLinkObject.class;

            //Class outerType = HalReflection.getFieldType( field );
            JsonElement element = rootObject.get(memberName);

            // TODO support collections

            /*if ( Collection.class.isAssignableFrom( outerType ) )
            {
            innerType.
            //noinspection unchecked
            Class<Collection> collectionClass = (Class<Collection>)outerType;
            Collection collection = gson.fromJson( element, collectionClass );
            }
                    
            field.getType()
                    
            if ( element.isJsonArray() ) {
            for ( JsonElement element1 : element.getAsJsonArray() )
                HalReflection.setLink( field, , deserialized );
            } else {
             */
            HalReflection.setLink(field, (HalLinkObject) gson.fromJson(element, (Type) innerType),
                    deserialized);
        }

    }.nullSafe();
}

From source file:cz.boris.gson.typeadapter.RuntimeTypeAdapterFactory.java

License:Apache License

public <R> TypeAdapter<R> create(Gson gson, TypeToken<R> type) {
    if (type.getRawType() != baseType) {
        return null;
    }/*w w  w. j a  v  a2  s .co m*/

    final Map<String, TypeAdapter<?>> labelToDelegate = new LinkedHashMap<String, TypeAdapter<?>>();
    final Map<Class<?>, TypeAdapter<?>> subtypeToDelegate = new LinkedHashMap<Class<?>, TypeAdapter<?>>();
    for (Map.Entry<String, Class<?>> entry : labelToSubtype.entrySet()) {
        TypeAdapter<?> delegate = gson.getDelegateAdapter(this, TypeToken.get(entry.getValue()));
        labelToDelegate.put(entry.getKey(), delegate);
        subtypeToDelegate.put(entry.getValue(), delegate);
    }

    return new TypeAdapter<R>() {
        @Override
        public R read(JsonReader in) throws IOException {
            JsonElement jsonElement = Streams.parse(in);
            JsonElement labelJsonElement = jsonElement.getAsJsonObject().remove(typeFieldName);
            if (labelJsonElement == null) {
                throw new JsonParseException("cannot deserialize " + baseType
                        + " because it does not define a field named " + typeFieldName);
            }
            String label = labelJsonElement.getAsString();
            @SuppressWarnings("unchecked")
            // registration requires that subtype extends T
            TypeAdapter<R> delegate = (TypeAdapter<R>) labelToDelegate.get(label);
            if (delegate == null) {
                throw new JsonParseException("cannot deserialize " + baseType + " subtype named " + label
                        + "; did you forget to register a subtype?");
            }
            return delegate.fromJsonTree(jsonElement);
        }

        @Override
        public void write(JsonWriter out, R value) throws IOException {
            Class<?> srcType = value.getClass();
            String label = subtypeToLabel.get(srcType);
            @SuppressWarnings("unchecked")
            // registration requires that subtype extends T
            TypeAdapter<R> delegate = (TypeAdapter<R>) subtypeToDelegate.get(srcType);
            if (delegate == null) {
                throw new JsonParseException(
                        "cannot serialize " + srcType.getName() + "; did you forget to register a subtype?");
            }
            JsonObject jsonObject = delegate.toJsonTree(value).getAsJsonObject();
            if (jsonObject.has(typeFieldName)) {
                throw new JsonParseException("cannot serialize " + srcType.getName()
                        + " because it already defines a field named " + typeFieldName);
            }
            JsonObject clone = new JsonObject();
            clone.add(typeFieldName, new JsonPrimitive(label));
            for (Map.Entry<String, JsonElement> e : jsonObject.entrySet()) {
                clone.add(e.getKey(), e.getValue());
            }
            Streams.write(clone, out);
        }
    };
}

From source file:data.RuntimeTypeAdapterFactory.java

License:Apache License

public <R> TypeAdapter<R> create(Gson g, TypeToken<R> type) {
    if (type == null || !baseType.isAssignableFrom(type.getRawType()))
        return null;

    final Map<String, TypeAdapter<?>> labelToDelegate = new LinkedHashMap<String, TypeAdapter<?>>();
    final Map<Class<?>, TypeAdapter<?>> subtypeToDelegate = new LinkedHashMap<Class<?>, TypeAdapter<?>>();
    for (Map.Entry<String, Class<?>> entry : labelToSubtype.entrySet()) {
        TypeAdapter<?> delegate = g.getDelegateAdapter(this, TypeToken.get(entry.getValue()));
        labelToDelegate.put(entry.getKey(), delegate);
        subtypeToDelegate.put(entry.getValue(), delegate);
    }/*from   w ww .  j a  va 2 s .  com*/

    return new TypeAdapter<R>() {
        @Override
        public R read(JsonReader in) throws IOException {
            JsonElement jsonElement = Streams.parse(in);
            JsonElement labelJsonElement = jsonElement.getAsJsonObject().remove(typeFieldName);
            if (labelJsonElement == null)
                throw new JsonParseException("cannot deserialize " + baseType
                        + " because it does not define a field named " + typeFieldName);
            String label = labelJsonElement.getAsString();
            @SuppressWarnings("unchecked") // registration requires that subtype extends T
            TypeAdapter<R> delegate = (TypeAdapter<R>) labelToDelegate.get(label);
            if (delegate == null)
                throw new JsonParseException("cannot deserialize " + baseType + " subtype named " + label
                        + "; did you forget to register a subtype?");
            return delegate.fromJsonTree(jsonElement);
        }

        @Override
        public void write(JsonWriter out, R value) throws IOException {
            Class<?> srcType = value.getClass();
            String label = subtypeToLabel.get(srcType);
            @SuppressWarnings("unchecked") // registration requires that subtype extends T
            TypeAdapter<R> delegate = (TypeAdapter<R>) subtypeToDelegate.get(srcType);
            if (delegate == null)
                throw new JsonParseException(
                        "cannot serialize " + srcType.getName() + "; did you forget to register a subtype?");
            JsonObject jsonObject = delegate.toJsonTree(value).getAsJsonObject();
            if (jsonObject.has(typeFieldName))
                throw new JsonParseException("cannot serialize " + srcType.getName()
                        + " because it already defines a field named " + typeFieldName);
            JsonObject clone = new JsonObject();
            clone.add(typeFieldName, new JsonPrimitive(label));
            for (Map.Entry<String, JsonElement> e : jsonObject.entrySet())
                clone.add(e.getKey(), e.getValue());
            Streams.write(clone, out);
        }
    }.nullSafe();
}

From source file:data_storage.RuntimeTypeAdapterFactory.java

License:Apache License

public <R> TypeAdapter<R> create(Gson gson, TypeToken<R> type) {
    // if (type.getRawType() != baseType) {
    // return null;
    // }/* w  w w . ja  v a 2 s . c  om*/

    if (!baseType.isAssignableFrom(type.getRawType())) {
        return null;
    }
    final Map<String, TypeAdapter<?>> labelToDelegate = new LinkedHashMap<String, TypeAdapter<?>>();
    final Map<Class<?>, TypeAdapter<?>> subtypeToDelegate = new LinkedHashMap<Class<?>, TypeAdapter<?>>();
    for (Map.Entry<String, Class<?>> entry : labelToSubtype.entrySet()) {
        TypeAdapter<?> delegate = gson.getDelegateAdapter(this, TypeToken.get(entry.getValue()));
        labelToDelegate.put(entry.getKey(), delegate);
        subtypeToDelegate.put(entry.getValue(), delegate);
    }

    return new TypeAdapter<R>() {
        @Override
        public R read(JsonReader in) throws IOException {
            JsonElement jsonElement = Streams.parse(in);
            JsonElement labelJsonElement = jsonElement.getAsJsonObject().remove(typeFieldName);
            if (labelJsonElement == null) {
                throw new JsonParseException("cannot deserialize " + baseType
                        + " because it does not define a field named " + typeFieldName);
            }
            String label = labelJsonElement.getAsString();
            @SuppressWarnings("unchecked")
            // registration requires that subtype extends T
            TypeAdapter<R> delegate = (TypeAdapter<R>) labelToDelegate.get(label);
            if (delegate == null) {
                throw new JsonParseException("cannot deserialize " + baseType + " subtype named " + label
                        + "; did you forget to register a subtype?");
            }
            return delegate.fromJsonTree(jsonElement);
        }

        @Override
        public void write(JsonWriter out, R value) throws IOException {
            Class<?> srcType = value.getClass();
            String label = subtypeToLabel.get(srcType);
            @SuppressWarnings("unchecked")
            // registration requires that subtype extends T
            TypeAdapter<R> delegate = (TypeAdapter<R>) subtypeToDelegate.get(srcType);
            if (delegate == null) {
                throw new JsonParseException(
                        "cannot serialize " + srcType.getName() + "; did you forget to register a subtype?");
            }
            JsonObject jsonObject = delegate.toJsonTree(value).getAsJsonObject();
            if (jsonObject.has(typeFieldName)) {
                throw new JsonParseException("cannot serialize " + srcType.getName()
                        + " because it already defines a field named " + typeFieldName);
            }
            JsonObject clone = new JsonObject();
            clone.add(typeFieldName, new JsonPrimitive(label));
            for (Map.Entry<String, JsonElement> e : jsonObject.entrySet()) {
                clone.add(e.getKey(), e.getValue());
            }
            Streams.write(clone, out);
        }
    };
}

From source file:de.chefkoch.api.serialize.RuntimeTypeAdapterFactory.java

License:Apache License

public <R> TypeAdapter<R> create(Gson gson, TypeToken<R> type) {
    if (type.getRawType() != baseType) {
        return null;
    }//w  ww .  j  ava 2  s  .c  o  m

    final Map<String, TypeAdapter<?>> labelToDelegate = new LinkedHashMap<String, TypeAdapter<?>>();
    final Map<Class<?>, TypeAdapter<?>> subtypeToDelegate = new LinkedHashMap<Class<?>, TypeAdapter<?>>();
    for (Map.Entry<String, Class<?>> entry : labelToSubtype.entrySet()) {
        TypeAdapter<?> delegate = gson.getDelegateAdapter(this, TypeToken.get(entry.getValue()));
        labelToDelegate.put(entry.getKey(), delegate);
        subtypeToDelegate.put(entry.getValue(), delegate);
    }

    return new TypeAdapter<R>() {
        @Override
        public R read(JsonReader in) throws IOException {
            JsonElement jsonElement = Streams.parse(in);
            JsonElement labelJsonElement = jsonElement.getAsJsonObject().remove(typeFieldName);
            if (labelJsonElement == null) {
                throw new JsonParseException("cannot deserialize " + baseType
                        + " because it does not define a field named " + typeFieldName);
            }
            String label = labelJsonElement.getAsString();
            @SuppressWarnings("unchecked")
            // registration requires that subtype extends T
            TypeAdapter<R> delegate = (TypeAdapter<R>) labelToDelegate.get(label);
            if (delegate == null) {
                //throw new JsonParseException("cannot deserialize " + baseType + " subtype named " + label + "; did you forget to register a subtype?");
                return null;
            }
            return delegate.fromJsonTree(jsonElement);
        }

        @Override
        public void write(JsonWriter out, R value) throws IOException {
            Class<?> srcType = value.getClass();
            String label = subtypeToLabel.get(srcType);
            @SuppressWarnings("unchecked")
            // registration requires that subtype extends T
            TypeAdapter<R> delegate = (TypeAdapter<R>) subtypeToDelegate.get(srcType);
            if (delegate == null) {
                throw new JsonParseException(
                        "cannot serialize " + srcType.getName() + "; did you forget to register a subtype?");
            }
            JsonObject jsonObject = delegate.toJsonTree(value).getAsJsonObject();
            if (jsonObject.has(typeFieldName)) {
                throw new JsonParseException("cannot serialize " + srcType.getName()
                        + " because it already defines a field named " + typeFieldName);
            }
            JsonObject clone = new JsonObject();
            clone.add(typeFieldName, new JsonPrimitive(label));
            for (Map.Entry<String, JsonElement> e : jsonObject.entrySet()) {
                clone.add(e.getKey(), e.getValue());
            }
            Streams.write(clone, out);
        }
    };
}