public TypeAdapter create()

in streampipes-storage-couchdb/src/main/java/org/apache/streampipes/storage/couchdb/serializer/RuntimeTypeAdapterFactory.java [98:153]
53 lines of code
8 McCabe index (conditional complexity)

  public <X> TypeAdapter<X> create(Gson gson, TypeToken<X> type) {
    if (type.getRawType() != baseType) {
      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<X>() {
      @Override
      public X 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<X> delegate = (TypeAdapter<X>) 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, X value) throws IOException {
        Class<?> srcType = value.getClass();
        String label = subtypeToLabel.get(srcType);
        @SuppressWarnings("unchecked") // registration requires that subtype extends T
        TypeAdapter<X> delegate = (TypeAdapter<X>) 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();
  }