A Complete Guide on Design Pattern in Java

In software engineering, a design pattern is a general repeatable solution to a commonly occurring problem in software design. A design pattern isn’t a finished design that can be transformed directly into code. It is a description or template for how to solve a problem that can be used in many different situations.

Uses of Design Patterns

Often, people only understand how to apply certain software design techniques to certain problems. These techniques are difficult to apply to a broader range of problems. Design patterns provide general solutions, documented in a format that doesn’t require specifics tied to a particular problem.

In addition, patterns allow developers to communicate using well-known, well understood names for software interactions. Common design patterns can be improved over time, making them more robust than ad-hoc designs.

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.

By using the design patterns you can make your code more flexible, reusable, and maintainable. It is the most important part because java internally follows design patterns.

If you want to become a professional software developer, you must know some popular solutions(design patterns) to the coding problems.

Advantage of design pattern:

  1. They provide the solutions that help to define the system architecture.
  2. They capture the software engineering experiences.
  3. They provide transparency to the design of an application.
  4. They are well-proved and testified solutions since they have been built upon the knowledge and experience of expert software developers.

We must use the design patterns during the analysis and requirement phase of SDLC(Software Development Life Cycle). It provides information based on prior hands-on experiences.

Categorization of design patterns:

  1. Core Java (or JSE) Design Patterns.
  2. JEE Design Patterns.

1. Core Java Design Patterns

1.1 Creational Design Pattern

1.2 Structural Design Pattern

1.3 Behavioral Design Pattern

2. JEE or J2EE Design Patterns

In J2EE, there are mainly three types of design patterns, which are further divided into their sub-parts:

2.1 Presentation Layer Design Pattern

2.2 Business Layer Design Pattern

2.3 Integration Layer Design Pattern

Software Engineer at Virtusa (Pvt) Ltd.