What are the best practices for using abstract classes in Java?

What are the best practices for using abstract classes in Java?

When using abstract classes in Java, it's important to ensure that they are used to define a common base for related classes. Here are some best practices:

1. Use abstract classes when you have a common base with shared behavior.
2. Keep the abstract class focused on a specific purpose.
3. Avoid using abstract classes for unrelated classes.
4. Use abstract methods to enforce implementation in subclasses.

Can you give me an example of an abstract class?

Sure! Here's a simple example:

abstract class Animal {
    abstract void makeSound();
}

class Dog extends Animal {
    void makeSound() {
        System.out.println("Bark");
    }
}

class Cat extends Animal {
    void makeSound() {
        System.out.println("Meow");
    }
}

In this example, Animal is an abstract class with an abstract method makeSound(). The Dog and Cat classes extend Animal and provide their own implementations.

What should I avoid when using abstract classes?

You should avoid the following:

1. Making an abstract class too broad, which can lead to confusion.
2. Overusing abstract classes when interfaces would be more appropriate.
3. Including concrete methods that are not relevant to all subclasses.

How do abstract classes differ from interfaces?

Abstract classes can have both abstract and concrete methods, while interfaces can only have abstract methods (prior to Java 8). Additionally, a class can extend only one abstract class but can implement multiple interfaces.