How to use

returns

method

in

net.bytebuddy.matcher.ElementMatchers

/**
 * Matches {@link MethodDescription}s that return a given erasure type.
 * @param type The raw type the matched method is expected to return.
 * @param <T>  The type of the matched object.
 * @return An element matcher that matches a given return type for a method description.
public static <T extends MethodDescription> ElementMatcher.Junction<T> returns(TypeDescription type) {
  return returns(is(type));

/**
 * Matches any Java bean getter method.
 * @param <T> The type of the matched object.
 * @return A matcher that matches any getter method.
public static <T extends MethodDescription> ElementMatcher.Junction<T> isGetter() {
  return takesArguments(0).and(not(returns(TypeDescription.VOID))).and(nameStartsWith("get").or(nameStartsWith("is").and(returnsGeneric(anyOf(boolean.class, Boolean.class)))));

/**
 * Matches any Java bean setter method.
 * @param <T> The type of the matched object.
 * @return A matcher that matches any setter method.
public static <T extends MethodDescription> ElementMatcher.Junction<T> isSetter() {
  return nameStartsWith("set").and(takesArguments(1)).and(returns(TypeDescription.VOID));

/**
 * Only matches the {@link Object#finalize()} method, even if it was overridden.
 * @param <T> The type of the matched object.
 * @return A matcher that only matches the {@link Object#finalize()} method.
public static <T extends MethodDescription> ElementMatcher.Junction<T> isFinalizer() {
  return named("finalize").and(takesArguments(0)).and(returns(TypeDescription.VOID));

/**
 * Only matches the {@link Object#toString()} method, also if it was overridden.
 * @param <T> The type of the matched object.
 * @return A matcher that only matches the {@link Object#toString()} method.
public static <T extends MethodDescription> ElementMatcher.Junction<T> isHashCode() {
  return named("hashCode").and(takesArguments(0)).and(returns(int.class));

/**
 * Only matches the {@link Object#equals(Object)} method, also if it was overridden.
 * @param <T> The type of the matched object.
 * @return A matcher that only matches the {@link Object#equals(Object)} method.
public static <T extends MethodDescription> ElementMatcher.Junction<T> isEquals() {
  return named("equals").and(takesArguments(TypeDescription.OBJECT)).and(returns(boolean.class));

/**
 * Only matches the {@link Object#toString()} method, also if it was overridden.
 * @param <T> The type of the matched object.
 * @return A matcher that only matches the {@link Object#toString()} method.
public static <T extends MethodDescription> ElementMatcher.Junction<T> isToString() {
  return named("toString").and(takesArguments(0)).and(returns(TypeDescription.STRING));

@Override
protected ElementMatcher.Junction<MethodDescription> getExtraMethodElementMatcher() {
  return named("getHandler").and(returns(named("org.springframework.web.servlet.HandlerExecutionChain")));

@Override
protected ElementMatcher.Junction<MethodDescription> getMethodElementMatcher() {
  return named("postProcessBeforeInitialization")
      .and(returns(Object.class))
      .and(takesArguments(Object.class, String.class));

@Override
protected ElementMatcher.Junction<MethodDescription> getExtraMethodElementMatcher() {
  return named("getPort").or(named("createDispatch").and(returns(named("javax.xml.ws.Dispatch"))));

private ProxyDefinitionHelpers() {
  this.groovyGetMetaClassFilter = isSynthetic().and( named( "getMetaClass" )
      .and( returns( td -> "groovy.lang.MetaClass".equals( td.getName() ) ) ) );
  this.virtualNotFinalizerFilter = isVirtual().and( not( isFinalizer() ) );
  this.hibernateGeneratedMethodFilter = nameStartsWith( "$$_hibernate_" ).and( isVirtual() );
  PrivilegedAction<MethodDelegation> delegateToInterceptorDispatcherMethodDelegationPrivilegedAction =
      new PrivilegedAction<MethodDelegation>() {
    @Override
    public MethodDelegation run() {
      return MethodDelegation.to( ProxyConfiguration.InterceptorDispatcher.class );
  this.delegateToInterceptorDispatcherMethodDelegation = System.getSecurityManager() != null
      ? AccessController.doPrivileged( delegateToInterceptorDispatcherMethodDelegationPrivilegedAction )
      : delegateToInterceptorDispatcherMethodDelegationPrivilegedAction.run();
  PrivilegedAction<FieldAccessor.PropertyConfigurable> interceptorFieldAccessorPrivilegedAction =
      new PrivilegedAction<FieldAccessor.PropertyConfigurable>() {
    @Override
    public FieldAccessor.PropertyConfigurable run() {
      return FieldAccessor.ofField( ProxyConfiguration.INTERCEPTOR_FIELD_NAME )
          .withAssigner( Assigner.DEFAULT, Assigner.Typing.DYNAMIC );
  this.interceptorFieldAccessor = System.getSecurityManager() != null
      ? AccessController.doPrivileged( interceptorFieldAccessorPrivilegedAction )
      : interceptorFieldAccessorPrivilegedAction.run();

@Override
protected ElementMatcher.Junction<MethodDescription> getExtraMethodElementMatcher() {
  return named("getConnection")
      .and(returns(Connection.class))
      .and(isPublic())
      .and(takesArguments(String.class, String.class).or(takesArguments(0)));

/**
 * {@inheritDoc}
public ByteCodeAppender appender(Target implementationTarget) {
  return new Appender(targetMethod.getOwnerType()
      .getDeclaredMethods()
      .filter(hasMethodName(targetMethod.getName())
          .and(returns(targetMethod.getReturnType()))
          .and(takesArguments(targetMethod.getParameterTypes())))
      .getOnly(),
      specializedLambdaMethod,
      implementationTarget.getInstrumentedType().getDeclaredFields());

.or(returns(isPackagePrivate()))
.or(hasParameters(whereAny(hasType(isPackagePrivate())))));

.and(returns(isVisibleTo(instrumentedType)))
.and(hasParameters(whereNone(hasType(not(isVisibleTo(instrumentedType))))))
.and(ignoredMethods.resolve(instrumentedType));

/**
 * {@inheritDoc}
public Compiled compile(TypeDescription instrumentedType) {
  MethodList<?> targets = new MethodList.Explicit<MethodDescription>(CompoundList.<MethodDescription>of(
      instrumentedType.getDeclaredMethods().filter(isStatic().or(isPrivate())),
      methodGraphCompiler.compile(instrumentedType).listNodes().asMethodList())
  ).filter(named(name).and(takesArguments(0)).and(not(returns(isPrimitive().or(isArray())))));
  if (targets.size() != 1) {
    throw new IllegalStateException(instrumentedType + " does not define method without arguments with name " + name + ": " + targets);
  } else if (!targets.getOnly().getReturnType().asErasure().isVisibleTo(instrumentedType)) {
    throw new IllegalStateException(targets.getOnly() + " is not visible to " + instrumentedType);
  } else {
    MethodList<?> candidates = methodGraphCompiler.compile(targets.getOnly().getReturnType(), instrumentedType)
        .listNodes()
        .asMethodList()
        .filter(matcher);
    List<MethodDelegationBinder.Record> records = new ArrayList<MethodDelegationBinder.Record>(candidates.size());
    MethodDelegationBinder methodDelegationBinder = TargetMethodAnnotationDrivenBinder.of(parameterBinders);
    for (MethodDescription candidate : candidates) {
      records.add(methodDelegationBinder.compile(candidate));
    return new Compiled.ForMethodReturn(targets.get(0), records);

/**
 * Creates a matcher where only overridable or declared methods are matched unless those are ignored. Methods that
 * are declared by the target type are only matched if they are not ignored. Declared methods that are not found on the
 * target type are always matched.
 * @param ignoredMethods A method matcher that matches any ignored method.
 * @param originalType   The original type of the instrumentation before adding any user methods.
 * @return A latent method matcher that identifies any method to instrument for a rebasement or redefinition.
protected static LatentMatcher<MethodDescription> of(LatentMatcher<? super MethodDescription> ignoredMethods, TypeDescription originalType) {
  ElementMatcher.Junction<MethodDescription> predefinedMethodSignatures = none();
  for (MethodDescription methodDescription : originalType.getDeclaredMethods()) {
    ElementMatcher.Junction<MethodDescription> signature = methodDescription.isConstructor()
        ? isConstructor()
        : ElementMatchers.<MethodDescription>named(methodDescription.getName());
    signature = signature.and(returns(methodDescription.getReturnType().asErasure()));
    signature = signature.and(takesArguments(methodDescription.getParameters().asTypeList().asErasures()));
    predefinedMethodSignatures = predefinedMethodSignatures.or(signature);
  return new InliningImplementationMatcher(ignoredMethods, predefinedMethodSignatures);

  @Override
  public boolean matches(TypeDescription targetInterface) {
    if (ElementMatchers.declaresMethod(named(targetMethod.getName())
        .and(returns(targetMethod.getReturnType().asErasure()))
        .and(takesArguments(targetMethod.getParameters().asTypeList().asErasures())))
        .matches(targetInterface)) {
      return true;
    } else {
      for (TypeDescription typeDescription : targetInterface.getInterfaces().asErasures()) {
        if (matches(typeDescription)) {
          return true;
    return false;

  @Override
  public boolean matches(MethodDescription targetMethod) {
    TypeDescription superClass = targetMethod.getDeclaringType().asErasure();
      superClass = superClass.getSuperClass().asErasure();
      if (declaresMethod(named(targetMethod.getName())
          .and(returns(targetMethod.getReturnType().asErasure()))
          .and(takesArguments(targetMethod.getParameters().asTypeList().asErasures()))
          .and(extraMethodMatcher))
          .matches(superClass)) {
        return true;
    } while (superClassMatcher.matches(superClass));
    return false;

    .method(named(lambdaMethodName)
        .and(takesArguments(lambdaMethod.getParameterTypes()))
        .and(returns(lambdaMethod.getReturnType())))
    .intercept(new LambdaMethodImplementation(targetMethod, specializedLambdaMethod));
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