{"id":44746,"date":"2015-09-30T06:34:48","date_gmt":"2015-09-30T03:34:48","guid":{"rendered":"http:\/\/www.javacodegeeks.com\/?p=44746"},"modified":"2023-12-07T11:18:55","modified_gmt":"2023-12-07T09:18:55","slug":"factory-method-design-pattern","status":"publish","type":"post","link":"https:\/\/www.javacodegeeks.com\/2015\/09\/factory-method-design-pattern.html","title":{"rendered":"Factory Method Design Pattern Example"},"content":{"rendered":"

This article is part of our Academy Course titled Java Design Patterns<\/a>.<\/em><\/p>\n

In this course you will delve into a vast number of Design Patterns and see how those are implemented and utilized in Java. You will understand the reasons why patterns are so important and learn when and how to apply each one of them. Check it out here<\/a>!<\/p>\n

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Table Of Contents<\/h4>\n
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1. Introduction<\/a><\/dt>\n
2. What is the Factory Method Pattern<\/a><\/dt>\n
3. Implementing the Factory Method Pattern<\/a><\/dt>\n
4. When to use the Factory Method Pattern<\/a><\/dt>\n
5. Factory Method Pattern in JDK<\/a><\/dt>\n
6. Download the Source Code<\/a><\/dt>\n<\/dl>\n<\/div>\n

<\/a>1. Introduction<\/h2>\n

In today\u2019s modern world, everyone is using software to facilitate their jobs. Recently, a product company has shifted the way they used to take orders from their clients. The company is now looking to use an application to take orders from them. They receive orders, errors in orders, feedback for the previous order, and responses to the order in an XML format. The company has asked you to develop an application to parse the XML and display the result to them.<\/p>\n

The main challenge for you is to parse an XML and display its content to the user. There are different XML formats depending on the different types of messages the company receives from its clients. Like, for example, an order type XML has different sets of xml tags as compared to the response or error XML. But the core job is the same; that is, to display to the user the message being carried in these XMLs.<\/p>\n

Although the core job is the same, the object that would be used varies according to the kind of XML the application gets from the user. So, an application object may only know that it needs to access a class from within the class hierarchy (hierarchy of different parsers), but does not know exactly which class from among the set of subclasses of the parent class is to be selected.<\/p>\n

In this case, it is better to provide a factory, i.e. a factory to create parsers, and at runtime a parser gets instantiated to do the job, according to the kind of XML the application receives from the user.<\/p>\n

The Factory Method Pattern, suited for this situation, defines an interface for creating an object, but let subclasses decide which class to instantiate. Factory Method lets a class defer instantiation to subclasses.<\/p>\n

Let us see some more details about the Factory Method Pattern and then we will use it to implement the XML parser for the application.<\/p>\n

<\/a>2. What is the Factory Method Pattern<\/h2>\n

The Factory Method Pattern gives us a way to encapsulate the instantiations of concrete types. The Factory Method pattern encapsulates the functionality required to select and instantiate an appropriate class, inside a designated method referred to as a factory method. The Factory Method selects an appropriate class from a class hierarchy based on the application context and other influencing factors. It then instantiates the selected class and returns it as an instance of the parent class type.

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The advantage of this approach is that the application objects can make use of the factory method to get access to the appropriate class instance. This eliminates the need for an application object to deal with the varying class selection criteria.<\/p>\n

\"Figure<\/a>
Figure 1<\/figcaption><\/figure><\/p>\n

Product<\/strong><\/p>\n