Java Utililty Methods Reflection Generic Type from Class

List of utility methods to do Reflection Generic Type from Class

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Description

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

Method

TypegetGenericType(Class clazz, int index)
Find the Generic Type of the form Class . 
ParameterizedType type = (ParameterizedType) clazz.getGenericSuperclass();
if (type.getActualTypeArguments() == null || type.getActualTypeArguments().length <= index) {
    throw new IllegalArgumentException("No generic type at the specified position");
return type.getActualTypeArguments()[index];
ClassgetGenericType(Class propertyType)
get Generic Type 
Class genericType = null;
TypeVariable[] typeParameters = propertyType.getTypeParameters();
if (typeParameters != null && typeParameters.length > 0) {
    Type[] bounds = typeParameters[0].getBounds();
    if (bounds != null && bounds.length > 0 && (bounds[0] instanceof Class)) {
        genericType = (Class) bounds[0];
return genericType;
ClassgetGenericType(Class clazz)
get Generic Type 
return getGenericType(clazz, 0);
ClassgetGenericType(Class clazz)
get Generic Type 
Type genericType = clazz.getGenericInterfaces()[0];
Class<?>[] classes = getActualClass(genericType);
if (classes.length == 0) {
    return null;
} else {
    return classes[0];
ClassgetGenericType(Class clazz, int index)
get Generic Type 
Type genType = clazz.getGenericSuperclass();
if (!(genType instanceof ParameterizedType)) {
    return Object.class;
Type[] params = ((ParameterizedType) genType).getActualTypeArguments();
if (index >= params.length || index < 0) {
    throw new RuntimeException("Index outof bounds");
if (!(params[index] instanceof Class)) {
    return Object.class;
return (Class<?>) params[index];
Type[]getGenericType(Class target)
get Generic Type 
if (target == null)
    return new Type[0];
Type[] types = target.getGenericInterfaces();
if (types.length > 0) {
    return types;
Type type = target.getGenericSuperclass();
if (type != null) {
...
TgetGenericType(Class type)
get Generic Type 
assert type != null;
ParameterizedType genericSuperclass = (ParameterizedType) type.getGenericSuperclass();
Type[] actualTypeArguments = genericSuperclass.getActualTypeArguments();
return (T) actualTypeArguments[0];
ObjectgetGenericType(Class type, Class clazz)
Obtain the concrete type used by an implementation of an interface that uses a generic type. 
Type[] interfaces = clazz.getGenericInterfaces();
for (Type iface : interfaces) {
    if (iface instanceof ParameterizedType) {
        ParameterizedType pi = (ParameterizedType) iface;
        if (pi.getRawType() instanceof Class) {
            if (type.isAssignableFrom((Class<?>) pi.getRawType())) {
                return getTypeParameter(clazz, pi.getActualTypeArguments()[0]);
@SuppressWarnings("unchecked")
Class<? extends T> superClazz = (Class<? extends T>) clazz.getSuperclass();
Object result = getGenericType(type, superClazz);
if (result instanceof Class<?>) {
    return result;
} else if (result instanceof Integer) {
    ParameterizedType superClassType = (ParameterizedType) clazz.getGenericSuperclass();
    return getTypeParameter(clazz, superClassType.getActualTypeArguments()[((Integer) result).intValue()]);
} else {
    return null;
ClassgetGenericType(Object o, Class declaringClass, int idx)
get Generic Type 
Class<?> clazz = o.getClass();
LinkedList<Class<?>> clazzStack = new LinkedList<Class<?>>();
while (!clazz.getSuperclass().equals(declaringClass)) {
    clazzStack.push(clazz);
    clazz = clazz.getSuperclass();
while (clazz != null) {
    ParameterizedType ptype = (ParameterizedType) clazz.getGenericSuperclass();
...
ClassgetGenericType(Type type, Class rawType, int index)
get Generic Type 
if (type instanceof ParameterizedType) {
    ParameterizedType ptype = (ParameterizedType) type;
    if (rawType.equals(ptype.getRawType())) {
        Type[] typeArguments = ptype.getActualTypeArguments();
        if (index >= typeArguments.length || index < 0) {
            throw new RuntimeException(
                    "index " + (index < 0 ? " must large then 0" : "out of arguments count"));
        return getRawType(typeArguments[index]);
return null;