Java Utililty Methods Reflection Generic Return Type

List of utility methods to do Reflection Generic Return Type

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Description

The list of methods to do Reflection Generic Return Type are organized into topic(s).

Method

ClassgetGenericClassFromMethodReturn(Method m)
get Generic Class From Method Return 
Type type = m.getGenericReturnType();
if (type instanceof ParameterizedType) {
    ParameterizedType pt = (ParameterizedType) type;
    return (Class) pt.getActualTypeArguments()[0];
return null;
ClassgetGenericReturnClass(Method method)
get Generic Return Class 
Class returnClazz = method.getReturnType();
Type genType = method.getGenericReturnType();
if (genType instanceof ParameterizedType) {
    Type[] params = ((ParameterizedType) genType).getActualTypeArguments();
    if ((params != null) && (params.length >= 0)) {
        returnClazz = (Class) params[0];
return returnClazz;
ClassgetGenericReturnType(Method m)
get Generic Return Type 
Type t = m.getGenericReturnType();
if (t instanceof ParameterizedType) {
    for (Type arg : ((ParameterizedType) t).getActualTypeArguments()) {
        return (Class) arg;
return null;
ClassgetGenericReturnTypeMap(Method method, boolean isAllowNull)
Returns the second generic type parameter of a return value by a field or method. 
Type t = method.getGenericReturnType();
Class result = getGenericType(t, 1);
if (!isAllowNull && result == null) {
    return Object.class;
return result;
TypegetGenericReturnTypeOfGenericInterfaceMethod(Class clazz, Method method)
Given an interface Method, look in the implementing class for the method that implements the interface's method to obtain generic type information. 
if (!method.getDeclaringClass().isInterface()) {
    return method.getGenericReturnType();
try {
    Method tmp = clazz.getMethod(method.getName(), method.getParameterTypes());
    return tmp.getGenericReturnType();
} catch (NoSuchMethodException e) {
return method.getGenericReturnType();
TypegetGenericReturnTypeOfGenericInterfaceMethod(Class clazz, Method method)
get Generic Return Type Of Generic Interface Method 
if (!method.getDeclaringClass().isInterface()) {
    return method.getGenericReturnType();
try {
    Method tmp = clazz.getMethod(method.getName(), method.getParameterTypes());
    return tmp.getGenericReturnType();
} catch (NoSuchMethodException e) {
return method.getGenericReturnType();
ClassgetGenericType(Type returnType, int index)
get Generic Type 
if (returnType instanceof ParameterizedType) {
    ParameterizedType type = (ParameterizedType) returnType;
    Type[] typeArguments = type.getActualTypeArguments();
    if (index >= typeArguments.length || index < 0) {
        throw new RuntimeException("invalid index : " + index);
    return (Class) typeArguments[index];
return (Class) returnType;