resolveTypeParameter() — netty Function Reference

Architecture documentation for the resolveTypeParameter() function in ReflectionUtil.java from the netty codebase.

Function java CommonUtil Internal calls 1

Entity Profile

CommonUtil→ Internal→ resolveTypeParameter() — netty Function Reference

Dependency Diagram

graph TD
  a5bea1aa_8419_848e_9649_5391157d2623["resolveTypeParameter()"]
  256133bf_a518_6230_b946_c6d646a25eb5["ReflectionUtil"]
  a5bea1aa_8419_848e_9649_5391157d2623 -->|defined in| 256133bf_a518_6230_b946_c6d646a25eb5
  d3ba72cb_b3af_6669_8eb0_62d09acd9ab8["fail()"]
  a5bea1aa_8419_848e_9649_5391157d2623 -->|calls| d3ba72cb_b3af_6669_8eb0_62d09acd9ab8
  style a5bea1aa_8419_848e_9649_5391157d2623 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

common/src/main/java/io/netty/util/internal/ReflectionUtil.java lines 71–138

    public static Class<?> resolveTypeParameter(final Object object,
                                                Class<?> parametrizedSuperclass,
                                                String typeParamName) {
        final Class<?> thisClass = object.getClass();
        Class<?> currentClass = thisClass;
        for (;;) {
            if (currentClass.getSuperclass() == parametrizedSuperclass) {
                int typeParamIndex = -1;
                TypeVariable<?>[] typeParams = currentClass.getSuperclass().getTypeParameters();
                for (int i = 0; i < typeParams.length; i ++) {
                    if (typeParamName.equals(typeParams[i].getName())) {
                        typeParamIndex = i;
                        break;
                    }
                }

                if (typeParamIndex < 0) {
                    throw new IllegalStateException(
                            "unknown type parameter '" + typeParamName + "': " + parametrizedSuperclass);
                }

                Type genericSuperType = currentClass.getGenericSuperclass();
                if (!(genericSuperType instanceof ParameterizedType)) {
                    return Object.class;
                }

                Type[] actualTypeParams = ((ParameterizedType) genericSuperType).getActualTypeArguments();

                Type actualTypeParam = actualTypeParams[typeParamIndex];
                if (actualTypeParam instanceof ParameterizedType) {
                    actualTypeParam = ((ParameterizedType) actualTypeParam).getRawType();
                }
                if (actualTypeParam instanceof Class) {
                    return (Class<?>) actualTypeParam;
                }
                if (actualTypeParam instanceof GenericArrayType) {
                    Type componentType = ((GenericArrayType) actualTypeParam).getGenericComponentType();
                    if (componentType instanceof ParameterizedType) {
                        componentType = ((ParameterizedType) componentType).getRawType();
                    }
                    if (componentType instanceof Class) {
                        return Array.newInstance((Class<?>) componentType, 0).getClass();
                    }
                }
                if (actualTypeParam instanceof TypeVariable) {
                    // Resolved type parameter points to another type parameter.
                    TypeVariable<?> v = (TypeVariable<?>) actualTypeParam;
                    if (!(v.getGenericDeclaration() instanceof Class)) {
                        return Object.class;
                    }

                    currentClass = thisClass;
                    parametrizedSuperclass = (Class<?>) v.getGenericDeclaration();
                    typeParamName = v.getName();
                    if (parametrizedSuperclass.isAssignableFrom(thisClass)) {
                        continue;
                    }
                    return Object.class;
                }

                return fail(thisClass, typeParamName);
            }
            currentClass = currentClass.getSuperclass();
            if (currentClass == null) {
                return fail(thisClass, typeParamName);
            }
        }
    }