Apex Abstract Classes

Understanding Abstract Classes in Apex

Abstract classes in Apex are used to define methods that must be created by the derived classes. They serve as templates, allowing developers to outline the structure of classes without implementing the methods themselves. This encourages consistency and enforces a standard across different implementations.

Abstract classes can contain both abstract methods (without implementation) and non-abstract methods (with implementation). This flexibility allows developers to define common behaviors while leaving room for customization in derived classes.

Creating an Abstract Class

To create an abstract class in Apex, use the abstract keyword. An abstract class can contain both abstract and concrete methods. Here's a simple example:

Implementing Abstract Methods

When you create a subclass that extends an abstract class, you must implement all of its abstract methods. Here's how you would implement the startEngine method in a subclass:

Why Use Abstract Classes?

Abstract classes are particularly useful in scenarios where a group of related classes shares some common behavior, but also has specific differences. By using abstract classes, you ensure that the common behavior is implemented once and shared across all related classes, while still allowing each class to provide its unique implementation details.

This approach enhances code reusability and maintainability, allowing for more flexible and organized code structures.

Abstract Classes vs Interfaces

It's important to distinguish between abstract classes and interfaces in Apex. While both can be used to define methods that must be implemented by derived or implementing classes, there are key differences:

• Abstract Classes: Can contain both abstract and non-abstract methods. They can also have instance variables.
• Interfaces: Can only contain method signatures and final variables (constants). All methods are implicitly abstract.

Choosing between abstract classes and interfaces depends on your specific needs, such as whether you need to share code among classes or simply define a contract.