Master Abstract Classes & Methods in Java for Cleaner Code

Introduction

Ever since its discovery in 1992, Java has come a long way in becoming the second most popular programming language globally. Given its worldwide acceptance and the increasing number of Java developers, ensuring a strong grasp of key concepts like abstract classes and abstract methods in Java is important for staying ahead of the curve.

To master the art of writing clean Java code, learn about these crucial topics, their importance, points of difference, usage, and more in this article.

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What is an Abstract Method in Java?

Abstract methods are defined as methods which only have a declaration (method signature) but no implementation. They are created using the ‘abstract’ keyword and are also known as subclass responsibility.

• Format

An abstract method is followed by a semicolon, instead of curly brackets.

• Location

An abstract method is found in the following places:

• Within an abstract class
• In a Java interface

Note: Beginners may often refer to it as an abstract function in Java. However, the correct term is abstract methods.

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How to Define an Abstract Class in Java?

An abstract class refers to a class which has been declared ‘abstract’. It can contain both abstract and regular methods, or even no abstract methods at all. This is also created using the ‘abstract’ keyword. It is possible to subclass abstract classes, but not to instantiate them.

• Format

A non-abstract class and the entire content of an abstract class are defined within a pair of curly brackets.

• Location

An abstract class can be found in the following places:

• Source code
• Java Standard Library
• Class hierarchies
• Java frameworks and libraries

Difference Between Abstract Class and Method in Java

Though abstract classes and abstract methods are often used together in Java, there are several differences between them. These include:

What is Abstract in Java?

In Java, the non-access modifier used for methods and classes, but not variables, is called an abstract keyword. It forms an important part of the abstraction mechanism in Java, which helps developers in defining abstract methods and classes that offer a blueprint to be followed by other classes.

The abstract keyword provides a variety of benefits, such as:

• Enabling polymorphism
• Achieving abstraction
• Promoting reusability of code
• Facilitates late binding

Definitions and Benefits of a Clean Java Code

Clean Java code is code that is simple, accessible, convenient to test, and maintainable. It is written using various best practices to ensure only justifiably complex code that is also bug-free.

The benefits of writing clean Java code are:

• Easy updation and modification even in the long run.
• Enables effective collaboration by understanding each other’s code.
• Lesser scope for making mistakes.
• Makes it easier to fix any issues and bugs in the code.
• Better performance as it improves the overall efficiency and runs faster.

Rules and Tips for Using Abstract Classes for a Cleaner Java Code

The theoretical knowledge of abstract classes requires supplementing it with important rules and tips regarding their usage for writing clean Java code. Some of these include:

• Restriction of Multiple Class Inheritance

In case an abstract class lacks method implementations, an interface can be used, as Java does not support multiple class inheritance.

• Abstract Class Inheritance

When a subclass extends an abstract class, it is necessary for it to implement either every defined abstract method present in the abstract class or declare itself as abstract.

• Planning the Class Hierarchy Well

Ensure your class hierarchy is diligently planned by avoiding too much nesting of abstract classes. This helps maintain a manageable, clean code.

• Apply the @Override Annotation

This annotation is particularly useful in indicating a method overriding in the superclass. It helps in making noticing and correcting mistakes during compilation more convenient.

• Restriction of Instantiation

The abstract classes’ instantiation is restricted in Java. However, a solution to this is the subclassing of abstract classes.

Rules and Tips for Using Abstract Methods for a Cleaner Java Code

With the following handy rules and tips for abstract methods usage, writing clean Java code becomes a breeze:

• Compulsory Use of Semicolon

An abstract method should always end with a semicolon (;), as it cannot have a body. Otherwise, the compiler will display a syntax error.

• Declaration of Abstract Method

An abstract method can be declared within either an interface or an abstract class, as it lacks an implementation.

• Positioning of a Regular Class

A non-abstract (regular) class cannot declare an abstract method because the former does not contain a method body. Thus, a regular class should always be present within an abstract class.

• Defining the Abstract Method in a Child Class

A child class must be declared abstract if its inherited abstract method is not implemented inside it. Avoiding this will lead to a syntax error.

• Avoiding Over-Abstraction

Making too many methods abstract can lead to increased complexity and difficult maintenance. Thus, only the optimum use of abstraction is advisable.

Summing Up

A strong understanding of abstract methods and classes is essential for writing clean Java code that is scalable and easy to maintain. With their meaning, differences, and related rules and tips discussed here, you can succeed in writing flawless Java code. Additionally, the benefits of clean code help you better understand its need.

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