co.codewizards.cloudstore.core.objectfactory

Class ObjectFactoryUtil

java.lang.Object

co.codewizards.cloudstore.core.objectfactory.ObjectFactoryUtil

public class ObjectFactoryUtil
extends Object

Simple API to use the ObjectFactory.

Devs should add the following import:

 import static co.codewizards.cloudstore.core.objectfactory.ObjectFactoryUtil.*;
 

They can then invoke one of the createObject(...) methods simply without any prefix.

In order to register a sub-class as replacement for a certain base-class, implementors have to provide a ClassExtension and register it using the ServiceLoader-mechanism.

Important: If a certain base-class should be replaceable using this mechanism, all occurrences of new MyBaseClass(...) in the entire code-base must be replaced by createObject(MyBaseClass.class, ...).

Important 2: It is urgently recommended not to use this approach, whenever it is possible to use a better solution, preferably a well-defined service (=> ServiceLoader). There are situations, though, e.g. data-model-classes (a.k.a. entities), where services are not possible and ObjectFactoryUtil + ClassExtension is the perfect solution.

Author:

Marco หงุ่ยตระกูล-Schulze - marco at codewizards dot co

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ObjectFactoryUtil()

Method Summary

Modifier and Type	Method and Description
static <T> T	createObject(Class<T> clazz) Create an instance of the given class or a sub-class registered as replacement.
static <T> T	createObject(Class<T> clazz, Class<?>[] parameterTypes, Object... parameters) Create an instance of the given class or a sub-class registered as replacement.
static <T> T	createObject(Class<T> clazz, Object... parameters) Create an instance of the given class or a sub-class registered as replacement.
static <T> Class<? extends T>	getExtendingClass(Class<T> clazz)

Methods inherited from class java.lang.Object

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

Constructor Detail

ObjectFactoryUtil

protected ObjectFactoryUtil()

Method Detail

createObject

public static <T> T createObject(Class<T> clazz)

Create an instance of the given class or a sub-class registered as replacement.

If at least one ClassExtension is registered for the given class, the ClassExtension with the highest priority is chosen and its extendingClass instantiated instead of the base-class passed as clazz.

This method always invokes the default constructor (without any parameters).

Parameters:

clazz - the base-class to be instantiated. Must not be null.

Returns:

the object instantiated either from the given base-class or a sub-class registered via ClassExtension. Never null.

See Also:

createObject(Class, Class[], Object...)

createObject

public static <T> T createObject(Class<T> clazz,
                                 Object... parameters)

Create an instance of the given class or a sub-class registered as replacement.

If at least one ClassExtension is registered for the given class, the ClassExtension with the highest priority is chosen and its extendingClass instantiated instead of the base-class passed as clazz.

This method tries to automatically find the best constructor matching the given parameters. If multiple constructors might match and they are not semantically the same (only doing some implicit conversions), you should instead use createObject(Class, Class[], Object...) and pass the specific parameter types.

Parameters:

clazz - the base-class to be instantiated. Must not be null.

parameters - the parameters to be passed to the constructor.

Returns:

the object instantiated either from the given base-class or a sub-class registered via ClassExtension. Never null.

See Also:

createObject(Class, Class[], Object...)

createObject

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

Create an instance of the given class or a sub-class registered as replacement.

If at least one ClassExtension is registered for the given class, the ClassExtension with the highest priority is chosen and its extendingClass instantiated instead of the base-class passed as clazz.

This method invokes the constructor matching exactly the given parameter-types. If parameterTypes is null, a matching constructor is searched automatically based on the concrete parameters.

Parameters:

clazz - the base-class to be instantiated. Must not be null.

parameterTypes - either null or the exact argument-types of the constructor to be invoked.

parameters - the parameters to be passed to the constructor.

Returns:

the object instantiated either from the given base-class or a sub-class registered via ClassExtension. Never null.

getExtendingClass

public static <T> Class<? extends T> getExtendingClass(Class<T> clazz)