Java Best Practices: Code Style, Documentation and Design Patterns

This blog teaches you how to write clean, maintainable and reusable Java code using code style, documentation and design patterns. You will learn the benefits and best practices of each topic and see some examples in Java.

1. Introduction

Java is one of the most popular and widely used programming languages in the world. It is known for its versatility, performance, and compatibility across different platforms and devices. However, writing Java code is not enough to ensure the quality and maintainability of your software projects. You also need to follow some Java best practices that will help you write clean, readable, and reusable code.

In this blog, you will learn about three important aspects of Java best practices: Java code style, Java documentation, and Java design patterns. These topics will help you improve your coding skills, avoid common errors and bugs, and design better solutions for complex problems. You will also see some examples of how to apply these best practices in your own Java code.

By the end of this blog, you will have a solid understanding of how to write high-quality Java code that follows the industry standards and best practices. You will also be able to use some tools and frameworks that will make your coding process easier and more efficient. So, let’s get started!

2. Java Code Style

One of the most important aspects of Java best practices is Java code style. Code style refers to the way you write, format, and organize your code. It includes things like naming conventions, indentation, spacing, comments, and other elements that affect the readability and consistency of your code. Why is code style important? Here are some reasons:

• Code style makes your code easier to read and understand, both for yourself and for others who may work on your code in the future.
• Code style helps you avoid errors and bugs, as well as find and fix them faster.
• Code style improves the quality and maintainability of your code, as well as the performance and security of your software.
• Code style shows your professionalism and respect for the coding standards and best practices of the Java community.

So, how can you improve your Java code style? In this section, you will learn about three main topics: naming conventions, formatting and indentation, and comments and Javadoc. These topics will help you write clear, consistent, and elegant Java code that follows the code style guidelines and best practices. Let’s start with naming conventions.

2.1. Naming Conventions

Naming conventions are rules that you follow when you name your variables, methods, classes, and other elements in your Java code. Naming conventions help you create meaningful and consistent names that convey the purpose and function of your code elements. They also help you avoid confusion and ambiguity, as well as potential errors and bugs caused by using the same name for different things or using different names for the same thing.

There are different types of naming conventions in Java, such as camel case, pascal case, snake case, and kebab case. These conventions differ in how they use capitalization, spacing, and punctuation to separate the words in a name. For example, here are some names in different naming conventions:

However, not all naming conventions are equally suitable for Java. In fact, Java has its own standard naming conventions that are widely accepted and followed by the Java community. These conventions are based on the Java Code Conventions document published by Oracle, which is the company that owns and maintains Java. You can find the document here.

The Java standard naming conventions are as follows:

• Use camel case for variables, methods, and parameters. Start with a lowercase letter and capitalize the first letter of each subsequent word. For example:

  int age;
  boolean isValid;
  void printMessage(String message);

• Use pascal case for classes, interfaces, and enums. Start with an uppercase letter and capitalize the first letter of each subsequent word. For example:

  class Person;
  interface Shape;
  enum Color;

• Use uppercase letters and underscores for constants. Separate the words with underscores. For example:

  final double PI = 3.14;
  final int MAX_VALUE = 100;

• Use descriptive and meaningful names that reflect the purpose and function of your code elements. Avoid using single letters, abbreviations, or generic names. For example:

  // bad names
  int x;
  String str;
  void foo();
  
  // good names
  int age;
  String name;
  void calculateArea();

• Use singular names for variables that hold a single value and plural names for variables that hold a collection of values. For example:

  int number; // singular
  int[] numbers; // plural

• Use verbs or verb phrases for methods and boolean variables. Start with a lowercase letter and capitalize the first letter of each subsequent word. For example:

  boolean isEven(int number);
  void sortArray(int[] array);

• Use nouns or noun phrases for classes, interfaces, enums, and non-boolean variables. Start with an uppercase letter and capitalize the first letter of each subsequent word. For example:

  class Student;
  interface Animal;
  enum Day;
  String message;

By following these naming conventions, you can write clear, consistent, and elegant Java code that follows the Java code style guidelines and best practices. You can also use some tools and frameworks that can help you check and enforce the naming conventions in your code, such as Checkstyle and SonarLint. In the next section, you will learn about formatting and indentation, another important aspect of Java code style.

2.2. Formatting and Indentation

Another important aspect of Java code style is formatting and indentation. Formatting and indentation refer to the way you arrange and align your code elements, such as braces, parentheses, operators, keywords, and statements. Formatting and indentation help you create a clear and consistent layout for your code, making it easier to read and understand. They also help you avoid syntax errors and bugs, as well as improve the performance and security of your software.

There are different styles and preferences for formatting and indentation in Java, such as K&R style, Allman style, Whitesmiths style, and GNU style. These styles differ in how they use spaces, tabs, and line breaks to separate and align the code elements. For example, here are some code snippets in different formatting and indentation styles:

public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello, world!");
    }
}

public class HelloWorld
{
    public static void main(String[] args)
    {
        System.out.println("Hello, world!");
    }
}

public class HelloWorld
    {
    public static void main(String[] args)
        {
        System.out.println("Hello, world!");
        }
    }

public class HelloWorld
{
  public static void main (String[] args)
    {
      System.out.println ("Hello, world!");
    }
}

However, not all formatting and indentation styles are equally suitable for Java. In fact, Java has its own standard formatting and indentation conventions that are widely accepted and followed by the Java community. These conventions are based on the Java Code Conventions document published by Oracle, which is the company that owns and maintains Java. You can find the document here.

The Java standard formatting and indentation conventions are as follows:

• Use four spaces for indentation. Do not use tabs, as they may cause alignment problems in different editors and platforms. For example:

  public class HelloWorld {
      public static void main(String[] args) {
          System.out.println("Hello, world!");
      }
  }

• Use braces to enclose the body of a class, method, or control structure. Place the opening brace at the end of the line that begins the body, and the closing brace at the beginning of the line that ends the body. For example:

  if (condition) {
      statement1;
      statement2;
  }

• Use spaces around operators, keywords, parentheses, and commas. Do not use spaces before or after a semicolon. For example:

  int result = a + b;
  for (int i = 0; i < n; i++) {
      System.out.println(i);
  }

• Use blank lines to separate logical sections of your code. For example, use a blank line before and after a method declaration, a control structure, or a comment. For example:

  public class HelloWorld {
  
      // This is a comment
      public static void main(String[] args) {
  
          System.out.println("Hello, world!");
      }
  }

• Use line breaks to avoid long lines of code that exceed 80 characters. Break the line after a comma or an operator, and align the new line with the beginning of the expression at the same level. For example:

  int result = a * b + c * d + e * f + g * h +
               i * j + k * l + m * n;

By following these formatting and indentation conventions, you can write clear, consistent, and elegant Java code that follows the Java code style guidelines and best practices. You can also use some tools and frameworks that can help you format and indent your code automatically, such as Eclipse and IntelliJ IDEA. In the next section, you will learn about comments and Javadoc, another important aspect of Java code style.

2.3. Comments and Javadoc

Comments and Javadoc are another important aspect of Java code style. Comments and Javadoc are annotations that you add to your code to explain its purpose, functionality, logic, and behavior. Comments and Javadoc help you document your code, making it easier to understand, maintain, and reuse. They also help you communicate with other developers who may work on your code in the future.

There are different types of comments and Javadoc in Java, such as single-line comments, multi-line comments, and Javadoc comments. These types differ in how they use symbols, syntax, and format to annotate the code. For example, here are some comments and Javadoc in Java:

// This is a single-line comment
// It starts with two slashes
// It ends at the end of the line

/* This is a multi-line comment
   It starts with a slash and an asterisk
   It ends with an asterisk and a slash */

/** This is a Javadoc comment
  * It starts with a slash and two asterisks
  * It ends with an asterisk and a slash
  * It can have tags and HTML elements
  * @param name The name of the person
  * @return A greeting message
  */

However, not all comments and Javadoc are equally useful and effective. In fact, Java has its own standard comments and Javadoc conventions that are widely accepted and followed by the Java community. These conventions are based on the Java Code Conventions document published by Oracle, which is the company that owns and maintains Java. You can find the document here.

The Java standard comments and Javadoc conventions are as follows:

• Use comments and Javadoc to explain the why and how of your code, not the what. Do not use comments and Javadoc to repeat or describe what your code does, as this can be inferred from the code itself. For example:

  // bad comment
  // add one to x
  x++;
  
  // good comment
  // increment x to avoid overflow
  x++;

• Use single-line comments for short and simple annotations that fit in one line. Use multi-line comments for longer and more complex annotations that span multiple lines. For example:

  // this is a single-line comment
  int x = 10;
  
  /* this is a multi-line comment
     that explains the logic of the
     following code block */
  if (x > 0) {
      // do something
  }

• Use Javadoc comments for documenting the specification of your classes, methods, and fields. A specification is a contract that defines the behavior, functionality, and parameters of your code elements. Use Javadoc tags and HTML elements to format and structure your Javadoc comments. For example:

  /** This is a Javadoc comment for the Person class
    * It represents a person with a name and an age
    * It has a constructor, getters, and setters
    */
  public class Person {
      // fields
      private String name;
      private int age;
  
      /** This is a Javadoc comment for the constructor
        * It initializes the name and age fields
        * @param name The name of the person
        * @param age The age of the person
        */
      public Person(String name, int age) {
          // code
      }
  
      /** This is a Javadoc comment for the getName method
        * It returns the name of the person
        * @return The name of the person
        */
      public String getName() {
          // code
      }
  
      /** This is a Javadoc comment for the setName method
        * It sets the name of the person
        * @param name The new name of the person
        */
      public void setName(String name) {
          // code
      }
  
      // other methods
  }

• Use comments and Javadoc sparingly and wisely. Do not overuse or misuse comments and Javadoc, as this can make your code cluttered, redundant, and outdated. Use comments and Javadoc only when they add value and clarity to your code. For example, do not use comments and Javadoc for:
  • Code that is self-explanatory and does not need any explanation.
  • Code that is not finished or not working.
  • Code that is obsolete or deprecated.
  • Code that is copied or modified from another source without proper attribution.

By following these comments and Javadoc conventions, you can write clear, consistent, and elegant Java code that follows the Java code style guidelines and best practices. You can also use some tools and frameworks that can help you generate and manage your comments and Javadoc, such as Eclipse and IntelliJ IDEA. In the next section, you will learn about Java documentation, another important aspect of Java best practices.

3. Java Documentation

Java documentation is another important aspect of Java best practices. Java documentation is the process of creating and maintaining external documents that describe your Java code, such as user manuals, API references, tutorials, and guides. Java documentation helps you communicate the purpose, functionality, and usage of your code to your target audience, such as end users, developers, testers, and managers. Java documentation also helps you promote and distribute your code, as well as improve its quality and reliability.

There are different types of Java documentation, such as user documentation, developer documentation, and technical documentation. These types differ in their scope, content, format, and audience. For example, here are some examples of Java documentation:

The Java API Specification developer documentation

Technical documentation is the documentation that explains how your Java code works internally from the perspective of a technical expert. It includes things like architecture diagrams, algorithms, data structures, and performance metrics. Technical documentation is usually written in a detailed and rigorous language, with mathematical expressions, pseudocode, and charts.

However, not all Java documentation are equally easy and effective to create and maintain. In fact, Java has its own standard Java documentation tools and frameworks that are widely used and recommended by the Java community. These tools and frameworks help you generate, manage, and update your Java documentation automatically, as well as ensure its quality and consistency. For example, here are some of the most popular and useful Java documentation tools and frameworks:

• Javadoc: Javadoc is a tool that generates HTML-based API documentation from Javadoc comments in your Java code. Javadoc is the standard and official tool for creating Java API documentation, and it is integrated with most Java IDEs and build tools. You can find more information about Javadoc here.
• Asciidoctor: Asciidoctor is a tool that converts plain text files written in AsciiDoc syntax into various formats, such as HTML, PDF, EPUB, and DocBook. Asciidoctor is a powerful and flexible tool for creating user and technical documentation, as well as books, articles, and slides. You can find more information about Asciidoctor here.
• Sphinx: Sphinx is a tool that generates HTML-based documentation from reStructuredText files. Sphinx is a popular and versatile tool for creating user and technical documentation, as well as tutorials, guides, and manuals. You can find more information about Sphinx here.

By using these Java documentation tools and frameworks, you can create and maintain high-quality Java documentation that follows the Java best practices and standards. You can also use some other tools and frameworks that can help you improve and enhance your Java documentation, such as MkDocs, Docusaurus, and Read the Docs. In the next section, you will learn about Java design patterns, another important aspect of Java best practices.

3.1. Why Document Your Code?

Another aspect of Java best practices is Java documentation. Documentation is the process of adding descriptive and explanatory information to your code, such as comments, annotations, and external documents. Documentation helps you and others understand the purpose, functionality, and usage of your code. But why is documentation important? Here are some benefits of documenting your code:

• Documentation makes your code more readable and understandable, especially for complex or unfamiliar parts of your code.
• Documentation helps you maintain and update your code, as well as debug and fix errors and bugs.
• Documentation facilitates collaboration and communication with other developers, users, and stakeholders who may work on or use your code.
• Documentation enhances the usability and reliability of your code, as well as the user satisfaction and trust.

So, how can you document your code effectively? In this section, you will learn about three main topics: why document your code, how to write effective documentation, and tools and frameworks for documentation. These topics will help you create clear, consistent, and comprehensive documentation for your Java code. Let’s start with why document your code.

3.2. How to Write Effective Documentation

Now that you know why document your code, you may wonder how to write effective documentation. Writing effective documentation is not an easy task, as it requires both technical and communication skills. However, there are some general principles and best practices that you can follow to create clear, consistent, and comprehensive documentation for your Java code. Here are some tips on how to write effective documentation:

• Know your audience. Before you start writing your documentation, you should identify who your target audience is and what their needs and expectations are. For example, are you writing for other developers, users, or managers? What is their level of expertise and familiarity with your code? What are their goals and challenges? Knowing your audience will help you tailor your documentation to their needs and preferences.
• Use the right format. Depending on the type and purpose of your documentation, you should choose the appropriate format and style for your documentation. For example, are you writing comments, annotations, Javadoc, or external documents? What are the conventions and standards for each format? How can you structure and organize your documentation to make it easy to navigate and understand? Using the right format will help you present your documentation in a professional and consistent way.
• Be clear and concise. Your documentation should be clear and concise, meaning that it should convey the essential information without being ambiguous or verbose. You should use simple and precise language, avoid jargon and acronyms, and explain any technical terms or concepts that may be unfamiliar to your audience. You should also avoid unnecessary details, repetitions, and digressions that may distract or confuse your audience. Being clear and concise will help you communicate your message effectively and efficiently.
• Be accurate and up-to-date. Your documentation should be accurate and up-to-date, meaning that it should reflect the current state and functionality of your code. You should verify that your documentation is correct and consistent with your code, and update it whenever you make any changes or improvements to your code. You should also indicate the date and version of your documentation, and provide a changelog or a history of revisions if applicable. Being accurate and up-to-date will help you maintain the quality and reliability of your documentation.
• Be helpful and engaging. Your documentation should be helpful and engaging, meaning that it should provide useful and relevant information that meets the needs and expectations of your audience. You should also try to make your documentation interesting and enjoyable to read, by using examples, diagrams, screenshots, or other visual aids that illustrate your points. You can also use questions, prompts, or feedback mechanisms to engage your audience and encourage them to interact with your documentation. Being helpful and engaging will help you enhance the usability and satisfaction of your documentation.

By following these tips, you will be able to write effective documentation for your Java code that follows the Java best practices. In the next section, you will learn about some tools and frameworks that will make your documentation process easier and more efficient.

3.3. Tools and Frameworks for Documentation

Writing effective documentation can be a challenging and time-consuming task, especially if you have to do it manually. Fortunately, there are some tools and frameworks that can help you automate and simplify your documentation process. These tools and frameworks can help you generate, format, and organize your documentation, as well as check and validate your documentation for errors and inconsistencies. In this section, you will learn about some of the most popular and useful tools and frameworks for documentation in Java. Here are some examples:

• Javadoc: Javadoc is a tool that generates HTML documentation from Java source code. It uses special comments, called doc comments, that describe the classes, methods, fields, parameters, and exceptions in your code. Javadoc also supports annotations, tags, and links that add more information and functionality to your documentation. Javadoc is the standard and recommended tool for documenting Java code, as it follows the Java code style and best practices. You can use Javadoc from the command line, from an IDE, or from a build tool like Maven or Gradle.
• Sphinx: Sphinx is a tool that generates HTML, PDF, ePub, and other formats of documentation from plain text files. It uses reStructuredText, a lightweight markup language, that allows you to write your documentation in a simple and natural way. Sphinx also supports extensions, themes, and plugins that add more features and customization to your documentation. Sphinx is a popular and versatile tool for documenting Python code, but it can also be used for documenting Java code, by using a plugin called javasphinx.
• Doxygen: Doxygen is a tool that generates HTML, LaTeX, RTF, and other formats of documentation from source code. It supports multiple programming languages, including Java, C++, C#, and others. It uses special comments, similar to Javadoc, that describe the elements and features of your code. Doxygen also supports graphs, diagrams, and images that visualize your code structure and dependencies. Doxygen is a powerful and flexible tool for documenting complex and multi-language projects.

These are just some of the tools and frameworks that you can use for documenting your Java code. There are many other options available, depending on your needs and preferences. You can also combine different tools and frameworks to create a customized documentation solution. The main point is to choose the tools and frameworks that suit your project and your audience, and that follow the Java best practices. In the next section, you will learn about another aspect of Java best practices: Java design patterns.

4. Java Design Patterns

The last aspect of Java best practices that we will cover in this blog is Java design patterns. Design patterns are general and reusable solutions for common problems that occur in software design. They are not specific code, but rather templates or guidelines that can be applied to different situations and scenarios. Design patterns help you improve your coding skills, avoid reinventing the wheel, and design better solutions for complex problems. But what are design patterns and how can you use them in Java? In this section, you will learn about three main topics: what are design patterns, types of design patterns, and examples of design patterns in Java. These topics will help you understand and apply design patterns in your Java code. Let’s start with what are design patterns.

4.1. What are Design Patterns?

Design patterns are general and reusable solutions for common problems that occur in software design. They are not specific code, but rather templates or guidelines that can be applied to different situations and scenarios. Design patterns help you improve your coding skills, avoid reinventing the wheel, and design better solutions for complex problems.

Design patterns were first introduced by a group of four authors, known as the Gang of Four (GoF), in their book Design Patterns: Elements of Reusable Object-Oriented Software. The book describes 23 design patterns, divided into three categories: creational, structural, and behavioral. Each design pattern has a name, a description, a motivation, a structure, a list of participants, a set of collaborations, a set of consequences, and some examples of implementation and usage.

Design patterns are not specific to Java, but they can be implemented in Java using the features and syntax of the language. For example, some design patterns use inheritance, polymorphism, interfaces, abstract classes, or inner classes to achieve their goals. Some design patterns also use design principles, such as the Single Responsibility Principle (SRP), the Open-Closed Principle (OCP), the Liskov Substitution Principle (LSP), the Interface Segregation Principle (ISP), and the Dependency Inversion Principle (DIP), to ensure the quality and maintainability of the code.

Design patterns are not mandatory or universal, but they are widely accepted and recommended by the Java community. They can help you write clean, readable, and reusable code that follows the Java best practices. However, you should also be aware of the trade-offs and limitations of each design pattern, and use them wisely and appropriately. In the next section, you will learn about the types of design patterns and their characteristics.

4.2. Types of Design Patterns

Design patterns can be classified into three main categories, based on the type of problem they solve and the level of abstraction they operate on. These categories are: creational, structural, and behavioral. Each category contains several design patterns that have different purposes and characteristics. Let’s take a look at each category and some of the design patterns it includes.

• Creational design patterns: Creational design patterns deal with the creation and initialization of objects. They provide various ways to create objects, without exposing the details of their implementation or requiring a specific constructor. Creational design patterns help you achieve loose coupling, flexibility, and reusability in your code. Some of the creational design patterns are: Singleton, Factory Method, Abstract Factory, Builder, and Prototype.
• Structural design patterns: Structural design patterns deal with the composition and organization of objects. They provide various ways to combine objects, either by inheritance or by composition, to form larger and more complex structures. Structural design patterns help you achieve modularity, scalability, and efficiency in your code. Some of the structural design patterns are: Adapter, Bridge, Composite, Decorator, Facade, and Proxy.
• Behavioral design patterns: Behavioral design patterns deal with the communication and interaction of objects. They provide various ways to define and control the behavior and responsibilities of objects, as well as the relationships and dependencies between them. Behavioral design patterns help you achieve cohesion, consistency, and clarity in your code. Some of the behavioral design patterns are: Chain of Responsibility, Command, Iterator, Mediator, Observer, and Strategy.

These are the three main categories of design patterns and some of the design patterns they contain. There are many other design patterns that belong to these categories or to other subcategories, such as concurrency or security. You can learn more about them from various sources, such as books, websites, or courses. In the next section, you will see some examples of how to implement and use design patterns in Java.

4.3. Examples of Design Patterns in Java

In this section, you will see some examples of how to implement and use design patterns in Java. You will learn how to apply some of the most common and useful design patterns from each category: creational, structural, and behavioral. You will also see how design patterns can help you solve some of the typical problems that you may encounter in your Java projects. Let’s start with some examples of creational design patterns.

Singleton

The Singleton design pattern ensures that only one instance of a class exists in the application. It also provides a global access point to that instance. The Singleton design pattern can be useful when you need to control the access and creation of a shared resource, such as a database connection, a configuration file, or a logger.

To implement the Singleton design pattern in Java, you need to do the following steps:

1. Declare a private static field that holds the single instance of the class.
2. Declare a private constructor that prevents the instantiation of the class from other classes.
3. Declare a public static method that returns the single instance of the class, creating it if necessary.

Here is an example of how to implement the Singleton design pattern in Java:

// A singleton class that represents a database connection
public class DatabaseConnection {

    // A private static field that holds the single instance of the class
    private static DatabaseConnection instance;

    // A private constructor that prevents the instantiation of the class from other classes
    private DatabaseConnection() {
        // Initialize the connection
    }

    // A public static method that returns the single instance of the class, creating it if necessary
    public static DatabaseConnection getInstance() {
        // Check if the instance is null
        if (instance == null) {
            // Create a new instance
            instance = new DatabaseConnection();
        }
        // Return the instance
        return instance;
    }

    // Other methods and fields of the class
}

To use the Singleton design pattern in Java, you need to do the following steps:

1. Call the getInstance() method of the singleton class to get the single instance of the class.
2. Use the instance to access the methods and fields of the class.

Here is an example of how to use the Singleton design pattern in Java:

// Get the single instance of the database connection
DatabaseConnection connection = DatabaseConnection.getInstance();

// Use the connection to perform some operations
connection.executeQuery("SELECT * FROM users");
connection.close();

5. Conclusion

In this blog, you have learned about three important aspects of Java best practices: Java code style, Java documentation, and Java design patterns. These topics will help you write clean, readable, and reusable Java code that follows the industry standards and best practices. You have also seen some examples of how to apply these best practices in your own Java code.

By following these best practices, you will be able to improve your coding skills, avoid common errors and bugs, and design better solutions for complex problems. You will also be able to use some tools and frameworks that will make your coding process easier and more efficient. You will also be able to collaborate and communicate with other developers, users, and stakeholders who may work on or use your code.

We hope that this blog has been useful and informative for you. If you have any questions, comments, or feedback, please feel free to leave them below. We would love to hear from you and help you with your Java projects. Thank you for reading and happy coding!