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Post By Admin Last Updated At 2021-01-19
What are the important Java design patterns?

Java is a general-purpose, object-oriented, and cross-platform supported programming language. It is useful as a server-side coding language for many back-end projects and developments of Big Data, Android, etc. Java design patterns are well-defined and proven solutions for resolving some general issues in software. There are a few benefits of using Java Design patterns.

In Java, these design patterns offer a conventional business approach to solve repeated issues. Hence, these design patterns save precious time for the users. Moreover, there are many Java design patterns that help in several Java projects.

The Java design patterns promote code reusability that leads to participation in any project more robust. It also offers high-maintainability of code by minimizing the ownership cost of the software product.

Moreover, Java design patterns are pre-defined which makes the code easily understandable and also debug the code. Therefore, it leads to faster development of any Java project and also useful for understanding by the new team members.

Let us understand these Java design patterns in detail with some examples.

Java design patterns with realtime examples

Using the Java design patterns, users can make their code more useful, flexible, reusable, and manageable. Mostly, Java follows these design patterns internally. These design patterns offer customization in designing solutions for the issues in software. Furthermore, Java design patterns are the result of efforts made by four people also known as GOF or Gang of four.

For instance, a user wants to build a class for which only a single object should be built. And the same object is useful for all classes.

Types of java design patterns

Then, he needs to use the “Singleton Design Pattern” which is the best solution considered to resolve that. Hence, to solve every problem or issue there are some set of design patterns available.

Here, a user needs to remember that design patterns are language-independent of programming. These include various strategies for solving common issues. Hence, it’s a type of idea and not an implementation.

To become a master in software development, you must know about any of these design patterns of solving issues. We will see these different types of Java design patterns in the following content.

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Benefits of using design patterns

There are many uses and benefits of using design patterns in Java. The following are-

Design patterns offer and encourage code reusability in several projects.

These patterns offer solutions for defining system architecture.

They help users to analyze the most abstract fields of a program by offering solid tested solutions.

It also helps to code faster by offering a clear picture of applying design patterns.

Moreover, they also offer transparency in app designing.

Furthermore, these Java design patterns are test proved solutions for software problems.

Hence, these are a few benefits of design patterns.

Types of Design Patterns in Java

There are three major design patterns in Java and they are further categorized into different sub-parts. These are Creational design patterns, Structural design patterns, and Behavioral design patterns.

Let us go in detailing these Java Design Patterns.

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Creational Design patterns in Java

The creational design patterns in Java deal with object creation or offer solutions to represent objects in the best possible way. Moreover, these Java design patterns are further subdivided into many different patterns.

Singleton Design Pattern

Factory Design Pattern

Prototype Design Pattern

Abstract Design Pattern

Builder Pattern

We will now elaborate on these Design Patterns in Java in the following paragraphs.

Singleton Design Pattern

Singleton Java design patterns restrict the representation of a class and make sure that under the JVM only a single class instance should exist. Here, the class should ensure that only one instance should be built and the only object is useful by other classes. The Singleton design pattern may look very easier or simple but there are some application concerns within it. As per the developers’ view, this is a controversial topic for them always been.

The major benefit of the Singleton pattern is that it saves a lot of memory due to single object creation. It doesn’t need to build objects repeatedly here, but the same object is reused again. This design pattern is most useful in multi-threaded apps. Furthermore, it is also useful in logging, thread pools, caching, etc.

Factory Pattern

In Java Design Patterns, the Factory pattern is useful while a user has a super excellent class with several sub-classes. Here, the user needs to describe a user interface or an abstract class for building an object. In this case, subclasses have the responsibility to represent a class from the program of the client to the factory class. Hence, the subclass has to decide which class it wants to represent. Also, this is a widely used design pattern among Java design patterns. Besides, “Virtual Constructor” is another name for the Factory Design pattern.

The major advantage of using the Factory method is that it enables the sub-classes to select the object type to build. It eliminates the need of binding application-particular classes into the code. Hence, the code interacts with the UI lonely.

Abstract Factory Pattern

The Abstract Factory Pattern in Design patterns in Java is similar to that of the Factory method. It has another name- “factory of factories”, and also it has the name “kit”. If you notice the Factory design patterns in Java, there will be a single factory class that returns the different sub-classes supported by the given input. Here, a user needs to describe an abstract class for building families of associated objects. But it doesn’t need to mention any concrete sub-class in this regard.

The benefit of using the Abstract Factory Java design patterns is that it separates the client code from implementing classes. Moreover, this pattern helps the exchange of object families. Also, it promotes regularity between the different objects. The Abstract Factory design patterns in Java is useful when the system needs configuration through more than one family object. It is also useful when the family of related objects is used in combination.

Builder Pattern

The Builder Design Pattern with Java Design Patterns is developed to resolve some of the issues within Factory and Abstract Factory Patterns. In this regard, the objects may include many attributes. This design pattern helps in building complex objects through a simple object in a step-wise approach.

Hence, this type of design pattern is most useful when there is an issue in building an object in a single step. These Java Design Patterns resolves the problems with a huge number of choices in parameters. Also, there may be an inconsistency in creating an object in various steps. This approach may return the final object as a result through a method.

The main advantages of this type of design patterns in Java are that-

It provides clean isolation among the building and instantiation of any object.

This design pattern also offers better control over the creation process.

These Java design patterns support the modification of the internal object representation.

For instance, to build a simple structure of the Builder design pattern, a user needs to follow the below-given steps.

  • Build a Packing (PI) interface
  • Develop two abstract classes:-DVD and Company
  • Build two implementation classes of Company: Sonata and Symphony
  • Develop the “DVDType” class
  • Build the “DVDBuilder” class
  • Finally, build the “BuilderDemo” class
Prototype Design Pattern

The prototype Java design pattern is useful when the development of an object becomes much expensive. Also, it needs a lot of time and resources to build and the user already has a similar object existing. Hence, this pattern offers a mechanism to copy the main object to an updated object. Later, change it as per your needs. This design pattern uses java cloning to copy the object.

In other words, it explains cloning of the current object instead of building the new object. Also, it allows modification according to the needs.

The advantages behind the Prototype design patterns in Java are-

It minimizes the requirement of sub-classing of an object.

Also, it removes hurdles in building objects.

Further, the clients will get some new design objects without the details about them.

Moreover, this pattern helps in adding or deleting objects in runtime mode.

Let us know the usage of this design pattern in brief. :-

It’s very useful in object instantiation at runtime when the object creation cost becomes much higher. Also, it becomes useful when a user wants to keep the classes’ number at the app’s minimum.

Structural Design Patterns

The Structural Design Patterns offer various ways to build the class structure. It is concerned with building classes and objects to develop huge structures. Besides, they simplify the structures by locating their relations. This Java Design Pattern concentrates on the class inheritance and composition to build objects larger.

There are various types of Structural Design Patterns under Design Patterns in Java. Such as-

  • Adapter Pattern
  • Bridge Pattern
  • Composite Pattern
  • Decorator Pattern
  • Proxy Pattern
  • Façade pattern
  • Flyweight Pattern

Now, we will look at each of these structural design patterns in Java.

Adapter Pattern

The Adapter Pattern under Structural Design Patterns in Java is useful to combine two different interfaces to work along. This system of combining two interfaces is Adapting and the object is known as Adapter. Here, a user needs to work according to the client’s expectation by adapting an interface to another one. A simple example to understand this pattern is the Mobile Charger. Here, the mobile charger works as an adapter or interface between the mobile and electricity socket that helps to charge mobile.

Composite Pattern

In the various Java design patterns, the Composite pattern under Structural design enables clients to operate on object hierarchy. Moreover, the composite design pattern is applicable when the structure is built in an alike way. This should be similar to the way in which object creation within the structure is treated.

For instance, we can see the objects we draw in various shapes like rectangle, circle, etc. And we fill some color in that. Then the color applies to the object in that shape only. Here, the operation of filling color is the same as it is drawn.

Proxy Pattern

The term proxy refers to the replacement of something. Here, the Proxy Design Pattern aims to replace or surrogate an existing object with another. The Proxy pattern in Java Design patterns is applicable when we need to generate controlled access to workability.

Façade Design Pattern

The Façade Design Pattern is useful to help client/customer apps to interact with the system that offers an interface. For instance, a user has an application with a set of interfaces to use Oracle or MYSQL database. And it requires producing several types of reports, like HTML report, PDF report, etc. 

Hence, he will have a different set of interfaces to work with various types of databases as above. Then a client app can use this set of interfaces to get the required database link and produce various reports. But the client application may find it difficult to handle when there is huge complexity or the interface action names are confusing. In this case, users can apply the Façade design pattern here. Also, they can provide an interface cover on top of the current interface to help the client app.

Bridge Pattern

The bridge design pattern separates or decouples an interface from implementation and also, it hides the implementations from the clients. These Java design patterns are like Adapter pattern within Structural design patterns.

Decorator Pattern

The Decorator design pattern deploys changes in the operability of an object at runtime. At a similar time, different instances of the same class won’t be affected by this change. Therefore, the single object gets the modified behavior in this pattern of Decorator.

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Behavioral Design Patterns

These Java Design Patterns offer better solutions for the interaction and responsibility among the objects. It mainly focuses on the loose coupling of the objects and also offers easy interaction and flexibility to enhance.

The Behavioral design patterns include many sub-categories. Such as 

  • Template method
  • Mediator Pattern
  • Chain of responsibility pattern
  • Observer Pattern
  • Command Pattern
  • Strategy Pattern
  • Visitor Patter
  • State Pattern
  • Interpreter Pattern and so on

Template method

The Template design method within Java describes the various stages to execute a rule. This rule will give default apps that may be general for all or several types of subclasses.

Mediator design pattern

The Mediator design patterns within Java design patterns deploys to generate a centralized contact interface. This contact should be between fully different objects in the next system.

Chain of responsibility pattern

This chain of responsibility pattern in Java deploys to gain loose-coupling within the software system design. It asks the consumer to pass a chain of objects to method them. In this, when the latest request enters into the system. Then it reaches the first object to attempt the processing. And it also gets fully processed after reaching a certain level.


Thus, we have gone through the various Java Design Patterns in this blog and their use. Also, we have seen a few real-time examples of these patterns. Hence, these Design patterns in Java are useful in solving general software issues with well-defined solutions. So, you can apply this variety of design patterns to solve complex issues in the software according to client needs. Furthermore, to get more practical insights into using these Java Design Patterns, go through Core Java Online Training from IT Guru experts. You can enhance your existing coding and designing skills with this learning.