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<div>The factory design pattern is used when we have a superclass with multiple subclasses and based on input, we need to return one of the subclasses. This pattern takes out the responsibility of the instantiation of a Class from the client program to the factory class. We can apply a singleton pattern on the factory class or make the factory method static.</div><div></div><div></div><div></div><div></div><div></div><div>java design patterns</div><div></div><div>Download: https://t.co/WyMeffakIN </div><div></div><div></div><div>The abstract factory pattern is similar to the factory pattern and is a factory of factories. If you are familiar with the factory design pattern in Java, you will notice that we have a single factory class that returns the different subclasses based on the input provided and the factory class uses if-else or switch statements to achieve this. In the abstract factory pattern, we get rid of if-else block and have a factory class for each subclass and then an abstract factory class that will return the subclass based on the input factory class.</div><div></div><div></div><div>The builder pattern was introduced to solve some of the problems with factory and abstract Factory design patterns when the object contains a lot of attributes. This pattern solves the issue with a large number of optional parameters and inconsistent state by providing a way to build the object step-by-step and provide a method that will actually return the final Object.</div><div></div><div></div><div>The prototype pattern is used when the Object creation is costly and requires a lot of time and resources, and you have a similar Object already existing. So this pattern provides a mechanism to copy the original Object to a new Object and then modify it according to our needs. This pattern uses Java cloning to copy the Object. The prototype design pattern mandates that the Object which you are copying should provide the copying feature. It should not be done by any other class. However, whether to use the shallow or deep copy of the object properties depends on the requirements and is a design decision.</div><div></div><div></div><div>The adapter design pattern is one of the structural design patterns and is used so that two unrelated interfaces can work together. The object that joins these unrelated interfaces is called an adapter.</div><div></div><div></div><div>The composite pattern is used when we have to represent a part-whole hierarchy. When we need to create a structure in a way that the objects in the structure have to be treated the same way, we can apply the composite design pattern.</div><div></div><div></div><div></div><div></div><div></div><div></div><div>The flyweight design pattern is used when we need to create a lot of Objects of a Class. Since every Object consumes memory space that can be crucial for low-memory devices (such as mobile devices or embedded systems), the flyweight design pattern can be applied to reduce the load on memory by sharing Objects.</div><div></div><div></div><div>When we have interface hierarchies in both interfaces as well as implementations, then the bridge design pattern is used to decouple the interfaces from the implementation and to hide the implementation details from the client programs. The implementation of the bridge design pattern follows the notion of preferring composition over inheritance.</div><div></div><div></div><div>The template method pattern is a behavioral design pattern and is used to create a method stub and to defer some of the steps of implementation to the subclasses. The template method defines the steps to execute an algorithm, and it can provide a default implementation that might be common for all or some of the subclasses.</div><div></div><div></div><div>The mediator design pattern is used to provide a centralized communication medium between different objects in a system. If the objects interact with each other directly, the system components are tightly-coupled with each other which makes maintainability cost higher and not flexible to extend easily. The mediator pattern focuses on providing a mediator between objects for communication and implementing loose-coupling between objects. The mediator works as a router between objects, and it can have its own logic to provide a way of communication.</div><div></div><div></div><div>The chain of responsibility pattern is used to achieve loose-coupling in software design where a request from the client is passed to a chain of objects to process them. Then the object in the chain will decide who will be processing the request and whether the request is required to be sent to the next object in the chain or not.</div><div></div><div></div><div>An observer design pattern is useful when you are interested in the state of an Object and want to get notified whenever there is any change. In the observer pattern, the Object that watches the state of another Object is called observer, and the Object that is being watched is called subject.</div><div></div><div></div><div>The state design pattern is used when an Object changes its behavior based on its internal state. If we have to change the behavior of an Object based on its state, we can have a state variable in the Object and use if-else condition block to perform different actions based on the state. The state pattern is used to provide a systematic and loosely-coupled way to achieve this through context and state implementations.</div><div></div><div></div><div>The iterator pattern is one of the behavioral patterns and is used to provide a standard way to traverse through a group of objects. The iterator pattern is widely used in Java Collection Framework where the iterator interface provides methods for traversing through a Collection. This pattern is also used to provide different kinds of iterators based on our requirements. The iterator pattern hides the actual implementation of traversal through the Collection and client programs use iterator methods.</div><div></div><div></div><div>The memento design pattern is used when we want to save the state of an object so that we can restore it later on. This pattern is used to implement this in such a way that the saved state data of the object is not accessible outside of the Object, this protects the integrity of saved state data.</div><div></div><div></div><div>The Data Access Object (DAO) design pattern is used to decouple the data persistence logic to a separate layer. DAO is a very popular pattern when we design systems to work with databases. The idea is to keep the service layer separate from the data access layer. This way we implement the separation of logic in our application.</div><div></div><div></div><div>This site showcases Java-based design patterns, principles, and code snippets. The</div><div></div><div> solutions have been developed by experienced programmers and architects from the</div><div></div><div> open source community. The patterns can be browsed by their high level descriptions</div><div></div><div> or by looking at their source code. The source code examples are well commented and</div><div></div><div> can be thought as programming tutorials on how to implement a specific pattern. We</div><div></div><div> use the most popular battle-proven open source Java technologies.</div><div></div><div></div><div>Solution:</div><div></div><div>Singleton design pattern is the best solution of above specific problem. So, every design pattern has some specification or set of rules for solving the problems. What are those specifications, you will see later in the types of design patterns.</div><div></div><div></div><div>But remember one-thing, design patterns are programming language independent strategies for solving the common object-oriented design problems. That means, a design pattern represents an idea, not a particular implementation.</div><div></div><div></div><div>Design patterns represent the best practices used by experienced object-oriented software developers. Design patterns are solutions to general problems that software developers faced during software development. These solutions were obtained by trial and error by numerous software developers over quite a substantial period of time.</div><div></div><div></div><div>This reference has been prepared for the experienced developers to provide best solutions to certain problems faced during software development and for un-experienced developers to learn software design in an easy and faster way.</div><div></div><div></div><div>Before you start proceeding with this tutorial, I'm making an assumption that you are already aware about basic java programming concepts. If you are not well aware of these concepts then I will suggest to go through our short tutorial on Java Programming.</div><div></div><div></div><div>I'm interested in the context of Java web developers working with Spring & Hibernate. I have often heard that good knowledge in design patterns is essential for working with those frameworks. Can anyone list the specifics?</div><div></div><div></div><div>The biggest advantage I've found to design patterns is sharing a common set of names. If someone says "Callback" that can mean quite a few things, but if someone says "Listener Pattern" that means a more specific set of calls and implies a higher level relationship between objects.</div><div></div><div></div><div>I am trying to explore more on java design patterns(e.g: Factory design pattern, Singleton design pattern or etc).So As an AEM developer I have question which design pattern we mostly use in AEM related use cases(e.g: sling models with services or web services call through sling Servlet...etc) and which could be the best fit to design most of our general AEM use cases.</div><div></div><div></div><div>We can use any design patterns that we like as OSGi makes CQ5 very modular, so we are free to use whatever suits our needs.Since AEM is built using OSGI, many of the design patterns for OSGI are valid.</div><div></div><div></div><div>I'm doing some self study before next semester and I wanted to get a leg up. Does anybody have any recommendations for books on design patterns & algorithms in Java. I'm currently reading Algorithms 4th edition but wanted to know if there was anything else out there that's better or close to the information I'm getting from this book. Thanks</div><div></div><div></div><div>Similar situations might arise in designing software. You may need to build an object using a subset of the options that are available. Or, you may need to create the object in multiple ways. This is where the builder pattern comes in handy.</div><div></div><div></div><div>The interface java.lang.Runnable is also a good example of how this pattern is implemented. We create threads in Java by extending the Runnable interface, which has all the logic for execution in its start() method. When we want to create and start a thread, we pass this class to the start() method.</div><div></div><div></div><div>I am reading Domain-Driven Design (DDD) and can't understand why we need to create so many classes. If we follow that method of designing software we end up with 20-30 classes which can be replaced with at most two files and 3-4 functions. Yes, this could be messy, but it's a lot more maintainable and readable.</div><div></div><div> 31c5a71286</div>
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