Java Utililty Methods Reflection Generic Type

List of utility methods to do Reflection Generic Type

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Description

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

Method

Type[]getGenericArguments(Type type)
Returns the generic type argument. 
if (type instanceof GenericArrayType) {
    return getGenericArguments(((GenericArrayType) type).getGenericComponentType());
} else if (type instanceof ParameterizedType) {
    ParameterizedType parameters = (ParameterizedType) type;
    return parameters.getActualTypeArguments();
} else {
    return new Class<?>[0];
Type[]getGenericElementType(Type type)
Retrieves type parameter from the parameterized type (either Map or Collection) specification. 
if (isGenericType(type)) {
    return ((ParameterizedType) type).getActualTypeArguments();
return null;
ClassgetGenericFirst(Object obj)
get Generic First 
Type type = (Type) obj.getClass().getGenericSuperclass();
ParameterizedType pt = (ParameterizedType) type;
Class classz = ((Class) pt.getActualTypeArguments()[0]);
return classz;
ListgetGenerics(Type genericType)
Returns the generic types represented in the given type. 
List<Type> classes = new ArrayList<Type>();
if (genericType instanceof ParameterizedType) {
    ParameterizedType ptype = (ParameterizedType) genericType;
    Type[] targs = ptype.getActualTypeArguments();
    for (Type targ : targs) {
        classes.add(targ);
return classes;
Class[]getGenerics(Type t)
get Generics 
Class[] generics = null;
if (t instanceof ParameterizedType) {
    ParameterizedType type = (ParameterizedType) t;
    Type[] typeArguments = type.getActualTypeArguments();
    generics = new Class[typeArguments.length];
    for (int i = 0; i < typeArguments.length; ++i) {
        generics[i] = (Class) typeArguments[i];
return generics;
StringgetGenericString(AccessibleObject ao)
Gets the generic string of the passed AccessibleObject 
if (ao == null)
    return null;
if (ao instanceof Method) {
    return ((Method) ao).toGenericString();
} else if (ao instanceof Constructor) {
    return ((Constructor<?>) ao).toGenericString();
} else if (ao instanceof Field) {
    Field f = (Field) ao;
...
TypegetGenericSuperType(Type t)
get Generic Super Type 
if (t instanceof Class) {
    return ((Class) t).getGenericSuperclass();
} else if (t instanceof ParameterizedType) {
    return getGenericSuperType(((ParameterizedType) t).getRawType());
return null;
ClassgetGenericType(@Nullable Type genericType)
Retrieves the generic subtype of the given type. 
if (genericType != null && genericType instanceof ParameterizedType) {
    Type[] types = ((ParameterizedType) genericType).getActualTypeArguments();
    if (types.length > 0 && types[0] instanceof Class<?>) {
        return (Class<?>) types[0];
return null;
ClassgetGenericType(Member member, int index)
Returns the actual generic type of a class's type parameter of the member. 
Type type;
if (member instanceof Field) {
    final Field field = (Field) member;
    type = field.getGenericType();
} else {
    final Method method = (Method) member;
    type = method.getGenericReturnType();
if (!(type instanceof ParameterizedType)) {
    return null;
final ParameterizedType parameterizedType = (ParameterizedType) type;
final Type[] types = parameterizedType.getActualTypeArguments();
return (Class<X>) ((types != null) && (index < types.length) ? types[index] : null);
ClassgetGenericType(Method setter)
get Generic Type 
if (setter != null) {
    Type[] genericParameterTypes = setter.getGenericParameterTypes();
    for (int i = 0; i < genericParameterTypes.length; i++) {
        if (genericParameterTypes[i] instanceof ParameterizedType) {
            Type[] parameters = ((ParameterizedType) genericParameterTypes[i]).getActualTypeArguments();
            if (parameters != null && parameters.length == 1) {
                return (Class<?>) parameters[0];
return null;