45.5. Java best practices and coding standards: Using Javadoc comments to document the API

When learning to program in Java, it is essential not only to understand the syntax and programming concepts, but also to adopt good coding practices and standards that will make the code more readable, maintainable, and professional. One such practice is the use of Javadoc comments to document the API. Javadoc is a tool provided by Oracle that generates documentation in HTML format from comments in Java code.

Javadoc comments start with /** and end with */, unlike regular single-line (//) or multi-line (/* */) comments. They are placed immediately before declarations of classes, interfaces, constructors, methods and class variables (static fields). The Javadoc is useful for both those who write the code and those who use it, as it provides a clear and consistent reference on how each element of the API works.

Good Practices with Javadoc

When documenting code with Javadoc, there are several best practices that should be followed:

• Describe the Purpose: Each Javadoc comment must clearly describe the purpose of the class, interface, method, or field it is documenting. This includes the expected behavior and, if it is a method, what it returns.
• Use Tags Consistently: Javadoc supports several tags that help structure documentation. Some of the most common include @param to describe method parameters, @return to describe the return value, @throws or @exception for exceptions that can be thrown, and @see to reference other related elements.
• Be Concise and Precise: Documentation should be concise but detailed enough to provide clear understanding. Avoid unnecessary information that does not help you understand the code.
• Keep Updated: As the code changes, the Javadoc documentation must also be updated to reflect the changes. Outdated documentation can be more harmful than no documentation.
• Document Exceptions: When a method can throw an exception, document each one with the @throws tag, explaining under what circumstances the exception is thrown.
• Avoid Generating Obvious Documentation: There is no need to document trivial getters and setters that simply set or return a field value without additional logic.

Javadoc Comment Example

/**
 * Class that represents a point in a two-dimensional coordinate system.
 * 

 * This class is used to model points on a plane. It provides methods for
 * calculate the distance between points and determine the relative location of a point.
 * 
 *
 * @author Author Name
 * @version 1.0
 */
public class Point {
    private double x;
    private double y;

    /**
     * Constructor that initializes a point with the specified coordinates.
     *
     * @param x The x coordinate of the point.
     * @param y The y coordinate of the point.
     */
    public Point(double x, double y) {
        this.x = x;
        this.y = y;
    }

    /**
     * Calculates the distance between this point and another point.
     *
     * @param other The other point to calculate the distance.
     * @return The Euclidean distance between the two points.
     */
    public double distanceAte(Point other) {
        double dx = other.x - this.x;
        double dy = other.y - this.y;
        return Math.sqrt(dx * dx + dy * dy);
    }

    // Other methods and comments...
}

Adopting good documentation practices with Javadoc is a sign of quality and professionalism in software development. The generated documentation can be integrated into integrated development environments (IDEs), code repositories, and can be published online to make the API easier to use and understand by other developers.

In addition to following good documentation practices, it is also important to adopt consistent coding standards, such as the naming of variables, methods and classes, the appropriate use of member visibility (public, private, etc.), and logical structuring of the code. This helps keep code organized, makes it easier to read and maintain, and promotes efficient code reuse.

In summary, using Javadoc comments to document the API is a fundamental practice in Java development. It not only makes the code easier to understand and use by other developers, but it also serves as a communication tool and a record of the intent behind the code's design. Therefore, when creating an e-book course on complete Java programming, it is essential to include a module dedicated to good documentation practices and coding standards in Java.