Java Utililty Methods Reflection Generic Parameter

List of utility methods to do Reflection Generic Parameter

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Description

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

Method

TypegetGenericParamType(Type type)
get Generic Param Type 
if (type instanceof ParameterizedType) {
    return type;
if (type instanceof Class) {
    return getGenericParamType(((Class<?>) type).getGenericSuperclass());
return type;
ClassgetGenericParamType(Type type)
Get the class of the parameter of the provided parameterized type. 
Class<?> generic = null;
if (type instanceof ParameterizedType) {
    ParameterizedType parameterizedType = (ParameterizedType) type;
    Type[] actualTypeArguments = parameterizedType.getActualTypeArguments();
    generic = (Class<?>) actualTypeArguments[0];
return generic;
ClassgetGenericParamType1(Type parameterizedType)
Get the parameterized type of a generic type GenericType For method, call method.getGenericParameterTypes() or method.getGenericReturnType() for the parameterizedType. 
if (parameterizedType instanceof ParameterizedType) {
    ParameterizedType type = (ParameterizedType) parameterizedType;
    Type[] typeArguments = type.getActualTypeArguments();
    if (typeArguments.length > 0)
        return (Class) typeArguments[0];
return null;
Class[]getGenericParamTypes(Type genericType)
get Generic Param Types 
Objects.requireNonNull(genericType, "Generic type is NULL!");
try {
    if (genericType instanceof ParameterizedType) {
        Type[] genericTypes = ((ParameterizedType) genericType).getActualTypeArguments();
        Class<?>[] result = new Class<?>[genericTypes.length];
        for (int i = 0; i < genericTypes.length; i++) {
            if (genericTypes[i] instanceof Class<?>) {
                result[i] = (Class<?>) genericTypes[i];
...
TypegetGenericType(Parameter param)
Attempts to infer the type in the generic part of the declaration of the type 
Type parameterizedType = param.getParameterizedType();
if (parameterizedType instanceof ParameterizedType) {
    parameterizedType = ((ParameterizedType) parameterizedType).getRawType();
return parameterizedType;
ClassgetGenericTypeParameter(Type genericType)
Get the type parameter out of a generic type. 
ParameterizedType fieldParamType = null;
if (genericType instanceof ParameterizedType) {
    fieldParamType = (ParameterizedType) genericType;
if (fieldParamType == null) {
    return Object.class;
Class typeParameter = (Class) fieldParamType.getActualTypeArguments()[0];
...
Type[]getGenericTypes(ParameterizedType t)
get Generic Types 
if (t == null)
    return new Type[] {};
else
    return t.getActualTypeArguments();
List>getGenericTypes(Type[] genericParameterTypes)
Returns a list of class's for every generic parameter type given by Method#getGenericParameterTypes() or Class#getGenericInterfaces() 
List<Class<?>> l = new ArrayList<>();
if (genericParameterTypes == null)
    return l;
try {
    for (Type t : genericParameterTypes) {
        ParameterizedType pType = (ParameterizedType) t;
        for (Type type : pType.getActualTypeArguments()) {
            l.add((Class<?>) type);
...