Java Reflection Method Parameter getMethodParameters(final Method method, final Map generics)

Description

Resolve generics in method parameters.

License

Open Source License

Parameter

Parameter	Description
method	method to resolve parameters
generics	type generics

Return

resolved method parameter types

Declaration

public static List<Class<?>> getMethodParameters(final Method method, final Map<String, Type> generics) 

Method Source Code

//package com.java2s;
//License from project: Open Source License 

import java.lang.reflect.*;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

public class Main {
    /**//  w  w  w .j a v a2s .  co m
     * Resolve generics in method parameters.
     *
     * @param method   method to resolve parameters
     * @param generics type generics
     * @return resolved method parameter types
     */
    public static List<Class<?>> getMethodParameters(final Method method, final Map<String, Type> generics) {
        final List<Class<?>> params = new ArrayList<Class<?>>();
        for (Type type : method.getGenericParameterTypes()) {
            params.add(resolveClass(type, generics));
        }
        return params;
    }

    /**
     * Resolves top class for provided type (for example, for generified classes like {@code List<T>} it
     * returns base type List).
     *
     * @param type     type to resolve
     * @param generics root class generics mapping
     * @return resolved class
     */
    public static Class<?> resolveClass(final Type type, final Map<String, Type> generics) {
        Class<?> res;
        if (type instanceof Class) {
            res = (Class) type;
        } else if (type instanceof ParameterizedType) {
            res = resolveClass(((ParameterizedType) type).getRawType(), generics);
        } else if (type instanceof TypeVariable) {
            res = resolveClass(generics.get(((TypeVariable) type).getName()), generics);
        } else if (type instanceof WildcardType) {
            final Type[] upperBounds = ((WildcardType) type).getUpperBounds();
            res = resolveClass(upperBounds[0], generics);
        } else {
            final Class arrayType = resolveClass(((GenericArrayType) type).getGenericComponentType(), generics);
            try {
                // returning complete array class with resolved type
                if (arrayType.isArray()) {
                    res = Class.forName("[" + arrayType.getName());
                } else {
                    res = Class.forName("[L" + arrayType.getName() + ";");
                }
            } catch (ClassNotFoundException e) {
                throw new IllegalStateException("Failed to create array class", e);
            }
        }
        return res;
    }
}

Related

1. getMethodGenericParameterTypes(Method method, int index)
2. getMethodHandle(final Lookup lookup, final Class receiver, final String methodName, final Class... parameterTypes)
3. getMethodName(Method method, Class[] parameterClasses, String rightCode)
4. getMethodParameterAnnotations(Method method, int index, Class annotationClass)
5. getMethodParameterIndexes(final Method m)
6. getMethodParametersType(Class clazz, String methodName)
7. getMethodParameterTypes(final Method method)
8. getMethodQuietly(Class clazz, String methodName, Class... parameterTypes)
9. getMethodRecursive(final Class clazz, final String methodName, final Class... parameterTypes)