{"id":44765,"date":"2015-09-30T06:37:23","date_gmt":"2015-09-30T03:37:23","guid":{"rendered":"http:\/\/www.javacodegeeks.com\/?p=44765"},"modified":"2023-12-07T11:20:36","modified_gmt":"2023-12-07T09:20:36","slug":"prototype-design-pattern","status":"publish","type":"post","link":"https:\/\/www.javacodegeeks.com\/2015\/09\/prototype-design-pattern.html","title":{"rendered":"Prototype 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 Prototype Design Pattern<\/a><\/dt>\n
3. Solution to the Problem<\/a><\/dt>\n
4. When to use the Prototype Design Pattern<\/a><\/dt>\n
5. Prototype Pattern in JDK<\/a><\/dt>\n
6. Download the Source Code<\/a><\/dt>\n<\/dl>\n<\/div>\n

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

In Object Oriented Programming, you need objects to work with; objects interact with each other to get the job done. But sometimes, creating a heavy object could become costly, and if your application needs too many of that kind of objects (containing almost similar properties), it might create some performance issues.<\/p>\n

Let us consider a scenario where an application requires some access control. The features of the applications can be used by the users according to the access rights provided to them. For example, some users have access to the reports generated by the application, while some don\u2019t. Some of them even can modify the reports, while some can only read it. Some users also have administrative rights to add or even remove other users.<\/p>\n

Every user object has an access control object, which is used to provide or restrict the controls of the application. This access control object is a bulky, heavy object and its creation is very costly since it requires data to be fetched from some external resources, like databases or some property files etc.<\/p>\n

We also cannot share the same access control object with users of the same level, because the rights can be changed at runtime by the administrator and a different user with the same level could have a different access control. One user object should have one access control object.<\/p>\n

We can use the Prototype Design Pattern to resolve this problem by creating the access control objects on all levels at once, and then provide a copy of the object to the user whenever required. In this case, data fetching from the external resources happens only once. Next time, the access control object is created by copying the existing one. The access control object is not created from scratch every time the request is sent; this approach will certainly reduce object creation time.<\/p>\n

Before digging into the solution, let us know more about the Prototype Design Pattern.<\/p>\n

<\/a>2. What is the Prototype Design Pattern<\/h2>\n

The Prototype design pattern is used to specify the kinds of objects to create using a prototypical instance, and create new objects by copying this prototype.<\/p>\n

The concept is to copy an existing object rather than creating a new instance from scratch, something that may include costly operations. The existing object acts as a prototype and contains the state of the object. The newly copied object may change same properties only if required. This approach saves costly resources and time, especially when the object creation is a heavy process.<\/p>\n

In Java, there are certain ways to copy an object in order to create a new one. One way to achieve this is using the Cloneable<\/code> interface. Java provides the clone<\/code> method, which an object inherits from the Object<\/code> class. You need to implement the Cloneable<\/code> interface and override this clone<\/code>method according to your needs.

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\"class_diagram_1\"<\/a>
Figure 1<\/figcaption><\/figure><\/p>\n

Prototype<\/strong><\/p>\n