lysine-dev/retrofit · error · NullPointerException

context == null

Error message

context == null

What it means

Thrown by JaxbConverterFactory.create(JAXBContext) as an explicit NullPointerException when the supplied JAXBContext is null. The no-arg create() deliberately passes null to the private constructor to signal 'create a fresh context per type', but the public create(JAXBContext) treats null as a programmer error and fails fast so the misconfiguration is reported at the call site, not later during conversion.

Source

Thrown at retrofit-converters/jaxb/src/main/java/retrofit2/converter/jaxb/JaxbConverterFactory.java:45

import retrofit2.Converter;
import retrofit2.Retrofit;

/**
 * A {@linkplain Converter.Factory converter} which uses JAXB for XML. All validation events are
 * ignored.
 */
public final class JaxbConverterFactory extends Converter.Factory {
  static final MediaType XML = MediaType.get("application/xml; charset=utf-8");

  /** Create an instance using a default {@link JAXBContext} instance for conversion. */
  public static JaxbConverterFactory create() {
    return new JaxbConverterFactory(null);
  }

  /** Create an instance using {@code context} for conversion. */
  @SuppressWarnings("ConstantConditions") // Guarding public API nullability.
  public static JaxbConverterFactory create(JAXBContext context) {
    if (context == null) throw new NullPointerException("context == null");
    return new JaxbConverterFactory(context);
  }

  /** If null, a new JAXB context will be created for each type to be converted. */
  private final @Nullable JAXBContext context;

  private JaxbConverterFactory(@Nullable JAXBContext context) {
    this.context = context;
  }

  @Override
  public @Nullable Converter<?, RequestBody> requestBodyConverter(
      Type type,
      Annotation[] parameterAnnotations,
      Annotation[] methodAnnotations,
      Retrofit retrofit) {
    if (type instanceof Class && ((Class<?>) type).isAnnotationPresent(XmlRootElement.class)) {
      return new JaxbRequestConverter<>(contextForType((Class<?>) type), (Class<?>) type);

View on GitHub (pinned to d0b112dad0)

Solutions

1. If you have no specific context, use the no-arg JaxbConverterFactory.create() instead of passing null.
2. If you intend to supply one, build it first: JaxbConverterFactory.create(JAXBContext.newInstance(MyClass.class)).
3. If using DI, ensure the JAXBContext @Provides/@Bean binding is present and returns non-null.
4. Catch/propagate any exception from JAXBContext.newInstance so the field is never silently null.

Example fix

// before
JAXBContext ctx = buildContextOrNull(); // null on failure
Retrofit retrofit = new Retrofit.Builder()
    .addConverterFactory(JaxbConverterFactory.create(ctx))
    .build();

// after — either pass a real context, or use the no-arg overload:
Retrofit retrofit = new Retrofit.Builder()
    .addConverterFactory(JaxbConverterFactory.create())
    .build();

JAXBContext context = resolveJaxbContext();
JaxbConverterFactory factory;
if (context == null) {
  factory = JaxbConverterFactory.create(); // legal: no-arg overload allows per-type context creation
} else {
  factory = JaxbConverterFactory.create(context);
}

// Kotlin: non-nullable parameter so the compiler rejects a null context.
fun converterFactory(context: JAXBContext): JaxbConverterFactory =
    JaxbConverterFactory.create(context)

JaxbConverterFactory factory;
try {
  factory = JaxbConverterFactory.create(resolveJaxbContext());
} catch (NullPointerException e) {
  if ("context == null".equals(e.getMessage())) {
    factory = JaxbConverterFactory.create(); // fall back to per-type context creation
  } else {
    throw e;
  }
}

When it happens

Trigger: Calling JaxbConverterFactory.create((JAXBContext) null) explicitly, or passing a variable that resolved to null (e.g. JAXBContext.newInstance(...) that the caller failed to assign, or a DI-provided context that was never bound).

Common situations: A DI provider returning null for JAXBContext because the binding was missing, a JAXB context build that threw and was swallowed leaving the field null, or confusing the no-arg create() (which is allowed to be null internally) with the one-arg overload (which is not).

Related errors

• gson == null
• mapper == null
• Response must be parameterized as Response<Foo> or Response<
• Result must be parameterized as Result<Foo> or Result<? exte
• Future return type must be parameterized as Future<Foo> or F

AI-assisted analysis of lysine-dev/retrofit@d0b112dad0 (2026-08-13). Data as JSON: /api/errors/a8d82bdd1a2c0cf3. Report an issue: GitHub.