Java Utililty Methods Reflection Generic Type from Field

List of utility methods to do Reflection Generic Type from Field

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Description

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

Method

ClassgetGenericType(Field field)
Similar to #getGenericType(Type[]) but only for fields 
return (Class<?>) ((ParameterizedType) field.getGenericType()).getActualTypeArguments()[0];
ClassgetGenericType(Field field)
Returns the generic type of an field. 
Type type = field.getGenericType();
return getGenericType(type);
ClassgetGenericType(Field field)
get Generic Type 
ParameterizedType type = (ParameterizedType) field.getGenericType();
return (Class<?>) type.getActualTypeArguments()[0];
TypegetGenericType(Type type, Type fieldType)
get Generic Type 
if (type instanceof ParameterizedType) {
    Class<?> klass = getTypeClass(type);
    if (fieldType instanceof TypeVariable) {
        TypeVariable<?>[] typeVariables = klass.getTypeParameters();
        for (int i = 0; i < typeVariables.length; i++) {
            TypeVariable<?> typeVariable = typeVariables[i];
            if (typeVariable.equals(fieldType)) {
                fieldType = ((ParameterizedType) type).getActualTypeArguments()[i];
...
List>getGenericTypeArguments(final Field field)
Attempts to return the actual generic type arguments of a field. 
final List<Class<?>> genericTypeArguments = new ArrayList<Class<?>>();
if (field.getGenericType() instanceof ParameterizedType) {
    final ParameterizedType parameterizedType = (ParameterizedType) field.getGenericType();
    for (final Type type : parameterizedType.getActualTypeArguments()) {
        if (type instanceof Class) {
            final Class<?> genericTypeArgument = (Class<?>) type;
            genericTypeArguments.add(genericTypeArgument);
return genericTypeArguments;
ClassgetGenericTypeOfCollectionField(Field field)
get Generic Type Of Collection Field 
Type genericType = field.getGenericType();
if (!(genericType instanceof ParameterizedType)) {
    throw new IllegalArgumentException("Field is not a ParameterizedType.");
Type[] genericTypes = ((ParameterizedType) genericType).getActualTypeArguments();
if (genericTypes.length != 1) {
    throw new IllegalArgumentException("Field does not have a single generic type.");
if (!(genericTypes[0] instanceof Class)) {
    throw new IllegalArgumentException("Field's generic type is not a class?");
return (Class<?>) genericTypes[0];
Class[]getGenericTypes(Field field)
Returns the list of generic types associated to the provided field (if any). 
try {
    ParameterizedType type = (ParameterizedType) field.getGenericType();
    Type[] types = type.getActualTypeArguments();
    Class<?>[] res = new Class<?>[types.length];
    for (int i = 0; i < types.length; i++) {
        res[i] = (Class<?>) types[i];
    return res;
...
SetgetGenericTypes(Field field)
get Generic Types 
if (field.getGenericType() instanceof ParameterizedType) {
    return getGenericTypes((ParameterizedType) field.getGenericType());
return new HashSet<>();
Type[]getGenericTypes(Field field)
get Generic Types 
Type type = field.getGenericType();
if (type == null) {
    return null;
if (type instanceof ParameterizedType) {
    ParameterizedType tc = (ParameterizedType) type;
    return tc.getActualTypeArguments();
return null;
Class[]getGenericTypes(Field field)
Returns the generic type information of an attribute. 
Type genericFieldType = field.getGenericType();
if (!(genericFieldType instanceof ParameterizedType))
    return null; 
ParameterizedType pType = (ParameterizedType) genericFieldType;
Type[] args = pType.getActualTypeArguments();
Class<?>[] types = new Class[args.length];
System.arraycopy(args, 0, types, 0, args.length);
return types;
...