Java Reflection Method Get from Object getMethodReturnTypeGeneric(Object source, Method method)

Description

Tries to retrieve the generic parameter of an ObjectProperty return by a method at runtime.

License

Open Source License

Declaration

public static Class getMethodReturnTypeGeneric(Object source, Method method) 

Method Source Code

//package com.java2s;
import java.lang.reflect.*;

public class Main {
    /**//ww  w . java 2 s . co m
     * Tries to retrieve the generic parameter of an ObjectProperty return by a method at runtime.
     */
    public static Class getMethodReturnTypeGeneric(Object source, Method method) {
        Type type = method.getGenericReturnType();
        if (type instanceof ParameterizedType) {
            return getGenericClass(source, (ParameterizedType) type);
        } else {
            return method.getReturnType();
        }
    }

    /**
     * Try to extract the generic type of the given ParameterizedType used in the given source object.
     *
     * @param source
     * @param type
     * @return
     */
    private static Class getGenericClass(Object source, ParameterizedType type) {
        Type type1 = type.getActualTypeArguments()[0];
        if (type1 instanceof ParameterizedType) {
            return (Class) ((ParameterizedType) type1).getRawType();
        } else if (type1 instanceof TypeVariable) {
            // Type is generic, try to get its actual type from the super class
            // e.g.: ObjectProperty<T> where T extends U
            if (source.getClass().getGenericSuperclass() instanceof ParameterizedType) {
                return (Class) ((ParameterizedType) source.getClass().getGenericSuperclass())
                        .getActualTypeArguments()[0];
            } else {
                // The actual type is not declared, use the upper bound of the type e.g. U
                return (Class) ((TypeVariable) type1).getBounds()[0];
            }
        } else {
            return (Class) type1;
        }
    }
}

Related

1. getMethodNames(Object obj, boolean includeInheritedMethods)
2. getMethodObject(Class type, Class clazz, String method, Class[] args, Object object, Object[] objects)
3. getMethodObject(Object object, String method, Object[] parametre)
4. getMethodResult(final Object element, final String methodName)
5. getMethodReturn(String className, String methodName, Class[] params, Object[] args, boolean isStatic)
6. getMethods(Class objectClass, Class annotationClass)
7. getMethods(Object instance, String name, Class[] arguments, boolean isPrefix)
8. getMethods(Object obj, boolean hasParent)
9. getMethods(Object obj, int cmpModifier, String prefix)