co.codewizards.cloudstore.core.util

Class ReflectionUtil

java.lang.Object

co.codewizards.cloudstore.core.util.ReflectionUtil

public class ReflectionUtil
extends Object

Method Summary

Modifier and Type	Method and Description
static List<Field>	getAllDeclaredFields(Class<?> clazz) Gets all fields declared by the given clazz including its super-classes; starting from the most concrete sub-class (i.e.
static Map<Field,Object>	getAllDeclaredFieldValues(Object object)
static Set<Class<?>>	getAllInterfaces(Class<?> clazz)
static <T> Constructor<T>	getDeclaredConstructorOrFail(Class<T> clazz, Class<?>[] parameterTypes)
static Method	getDeclaredMethod(Class<?> clazz, String name, Class<?>[] parameterTypes)
static Method	getDeclaredMethodOrFail(Class<?> clazz, String name, Class<?>[] parameterTypes)
static List<Method>	getDeclaredMethods(Class<?> clazz, String name)
static <V> V	getFieldValue(Object object, String fieldName)
static <T> T	invoke(Object object, String methodName, Class<?>[] parameterTypes, Object... args)
static <T> T	invoke(Object object, String methodName, Object... args)
static <T> T	invokeConstructor(Class<T> clazz, Class<?>[] parameterTypes, Object... args)
static <T> T	invokeConstructor(Class<T> clazz, Object... args)
static <T> T	invokeStatic(Class<?> clazz, String methodName, Class<?>[] parameterTypes, Object... args)
static <T> T	invokeStatic(Class<?> clazz, String methodName, Object... args)
static <T> Type[]	resolveActualTypeArguments(Class<T> baseClass, Class<? extends T> concreteClass) Resolves the actual type arguments of a base-class declared in a concrete sub-class.
static <T> Type[]	resolveActualTypeArguments(Class<T> baseClass, T concreteObject) Resolves the actual type arguments of a base-class declared in a concrete sub-class.
static void	setFieldValue(Object object, String fieldName, Object value) Sets the object's field – identified by fieldName – to the given value.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

invokeConstructor

public static <T> T invokeConstructor(Class<T> clazz,
                                      Object... args)

invokeConstructor

public static <T> T invokeConstructor(Class<T> clazz,
                                      Class<?>[] parameterTypes,
                                      Object... args)

invokeStatic

public static <T> T invokeStatic(Class<?> clazz,
                                 String methodName,
                                 Object... args)

invokeStatic

public static <T> T invokeStatic(Class<?> clazz,
                                 String methodName,
                                 Class<?>[] parameterTypes,
                                 Object... args)

invoke

public static <T> T invoke(Object object,
                           String methodName,
                           Object... args)

invoke

public static <T> T invoke(Object object,
                           String methodName,
                           Class<?>[] parameterTypes,
                           Object... args)

getDeclaredMethods

public static List<Method> getDeclaredMethods(Class<?> clazz,
                                              String name)

getDeclaredConstructorOrFail

public static <T> Constructor<T> getDeclaredConstructorOrFail(Class<T> clazz,
                                                              Class<?>[] parameterTypes)

getDeclaredMethodOrFail

public static Method getDeclaredMethodOrFail(Class<?> clazz,
                                             String name,
                                             Class<?>[] parameterTypes)

getDeclaredMethod

public static Method getDeclaredMethod(Class<?> clazz,
                                       String name,
                                       Class<?>[] parameterTypes)

getAllDeclaredFields

public static List<Field> getAllDeclaredFields(Class<?> clazz)

Gets all fields declared by the given clazz including its super-classes; starting from the most concrete sub-class (i.e. the given clazz).

Please note that the order of the fields declared by one single class is unspecified according to the Java specification. The only guaranteed order is that between fields declared by one class and fields declared by its super-classes: The result of this method begins with fields of the most concrete class, followed by its super-class's fields, followed by the fields of the super-class' super-class and so on.

For example, consider the following classes: Roadster extends Car extends Vehicle. This method would thus return all fields declared by all three classes, starting with the fields of Roadster, followed by the fields of Car and finally followed by the fields of Vehicle.

Parameters:

clazz - the class whose fields to obtain.

Returns:

the list of fields declared by the given class and all its super-classes. Never null, but maybe empty.

getAllDeclaredFieldValues

public static Map<Field,Object> getAllDeclaredFieldValues(Object object)

getFieldValue

public static <V> V getFieldValue(Object object,
                                  String fieldName)

setFieldValue

public static void setFieldValue(Object object,
                                 String fieldName,
                                 Object value)

Sets the object's field – identified by fieldName – to the given value.

The fieldName can be simple (e.g. "firstName") or fully qualified (e.g. "co.codewizards.bla.Person.firstName"). If it is simple, the most concrete sub-class' matching field is used.

Parameters:

object - the object whose field to manipulate. Must not be null.

fieldName - the simple or fully qualified field name (fully qualified means prefixed by the class name). Must not be null.

value - the value to be assigned. May be null.

getAllInterfaces

public static Set<Class<?>> getAllInterfaces(Class<?> clazz)

resolveActualTypeArguments

public static final <T> Type[] resolveActualTypeArguments(Class<T> baseClass,
                                                          T concreteObject)

Resolves the actual type arguments of a base-class declared in a concrete sub-class.

This is a convenience method delegating to resolveActualTypeArguments(Class, Class) passing concreteObject.getClass() as concreteClass.

Parameters:

baseClass - the base class. Must not be null.

concreteObject - an instance of a sub-class of the generic baseClass.

Returns:

the resolved type arguments. Never null (empty array for a non-generic base-class).

resolveActualTypeArguments

public static final <T> Type[] resolveActualTypeArguments(Class<T> baseClass,
                                                          Class<? extends T> concreteClass)

Resolves the actual type arguments of a base-class declared in a concrete sub-class.

The length as well as the order of the resolved type arguments matches the declaration order in the base-class. If a type argument could successfully be resolved, it is usually an instance of Class. If it could not be resolved (because the sub-class does not specify the generic type info - directly or indirectly), it is an instance of TypeVariable.

A typical use-case is this:

 public abstract class MyBase<A, B, C> {
   final Class<A> actualTypeArgumentA;
   final Class<B> actualTypeArgumentB;
   final Class<C> actualTypeArgumentC;

   public MyBase() {
     final Type[] actualTypeArguments = resolveActualTypeArguments(MyBase.class, this);

     // The following assignments fail - of course -, if the concrete class lacks
     // generic type info - like the example class "MyFail" below.
     actualTypeArgumentA = (Class<A>) actualTypeArguments[0];
     actualTypeArgumentB = (Class<B>) actualTypeArguments[1];
     actualTypeArgumentC = (Class<C>) actualTypeArguments[2];
   }
 }

 public class MyConcrete extends MyBase<Long, Boolean, String> {
 }

 public class MyFail extends MyBase {
 }
 

Parameters:

baseClass - the base class. Must not be null.

concreteClass - a sub-class of the generic baseClass.

Returns:

the resolved type arguments. Never null (empty array for a non-generic base-class).