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Creational Patterns in Java Access Code 128 Code Set A in Java Creational Patterns




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Creational Patterns generate, create barcode 128 none in java projects Visual Studio 2005 Creational patter code 128b for Java ns support the creation of objects in a system. Creational patterns allow objects to be created in a system without having to identify a speci c class type in the code, so you do not have to write large, complex code to instantiate an object. It does this by having the subclass of the class create the objects.

However, this can limit the type or number of objects that can be created within a system. The Creational patterns are Abstract Factory, Builder, Factory Method, Prototype, and Singleton..

Abstract Factory Pattern This pattern prov spring framework Code128 ides an interface for creating families of related or dependent objects without specifying their concrete classes. Given a set of related abstract classes, the Abstract Factory pattern provides a way to create instances of those abstract classes from a matched set of concrete subclasses. Figure 7-1 illustrates the Abstract Factory pattern.

The Abstract Factory pattern provides an abstract class that determines the appropriate concrete class to instantiate to create a set of concrete products that implement a standard interface. The client interacts only with the product interfaces and the Abstract Factory class. The client never knows about the concrete construction classes provided by this pattern.

The Abstract Factory pattern is similar to the Factory Method pattern, except it creates families of related objects.. 7 Applying Patterns Figure 7-1. Abstract Factory pattern diagram Bene ts The following lis ts the bene ts of using the Abstract Factory pattern:. Isolates the conc jdk ANSI/AIM Code 128 rete classes from client Allows for exchanging product families easy Promotes consistency among products by implementing the common interface. When to Use You should use th barcode 128 for Java e Abstract Factory pattern when:. The system should be independent of how its products are created, composed, and represented. The system should be con gured with one of multiple families of products for example, Microsoft Windows or Apple OSX classes. The family of related product objects is designed to be used together, and you must enforce this constraint.

This is the key point of the pattern; otherwise, you could use a Factory Method. You want to provide a class library of products, and reveal only their interfaces, not their implementations..

Discussion Builder Pattern The Builder patte barcode standards 128 for Java rn separates the construction of a complex object from its representation so the same construction process can create different objects. The Builder pattern allows a client object to construct a complex object by specifying only its type and content. The client is shielded from the details of the object s construction.

This simpli es the creation of complex objects by de ning a class that builds instances of another class. The Builder pattern produces one main product, and there might be more than one class in the product, but there is always one main class. Figure 7-2 illustrates the Builder pattern.

. Figure 7-2. Builder pattern diagram When you use the Builder pattern, you create the complex objects one step at a time. Other patterns build the object in a single step..

Bene ts The following lis ts the bene ts of using the Builder pattern:. Lets you vary a p ANSI/AIM Code 128 for Java roduct s internal representation Isolates code for construction and representation Gives you greater control over the construction process. When to Use You should use the Builder pattern when The algorithm for creating a complex object should be independent of both the parts that make up the object and how these parts are assembled.. 7 Applying Patterns The construction process must allow different representations of the constructed object. Factory Method Pattern The Factory Metho d pattern de nes an interface for creating an object, but lets the subclasses decide which class to instantiate. The Factory Method lets a class defer instantiation to subclasses, which is useful for constructing individual objects for a speci c purpose without the requestor knowing the speci c class being instantiated. This enables you to introduce new classes without modifying the code because the new class implements only the interface so it can be used by the client.

You create a new factory class to create the new class, and the factory class implements the factory interface. Figure 7-3 illustrates the Factory Method pattern..

Figure 7-3.
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