What are Abstract Classes in Java and How Do They Enable Polymorphism?

Understanding Abstract Classes in Java

An abstract class in Java is a blueprint for subclasses, providing common methods and an interface between them. Unlike regular classes, abstract classes cannot be instantiated directly, allowing only their subclasses to be created through inheritance.

Core Functionality of Abstract Classes:

• Define methods and fields that are inherited by subclasses.
• Declare abstract methods that must be implemented by subclasses.
• Enforce a common interface, enabling subclasses to substitute for each other seamlessly.

Key Properties of Abstract Methods:

• Abstract methods lack method bodies, indicating that they must be implemented in subclasses.
• Subclasses cannot instantiate abstract classes without providing implementations for all abstract methods.
• Subclasses may override defined methods, including the implementedMethod() shown in the example code.

Creating a Single Implementation of an Abstract Class:

`
public class ImplementingClass extends AbstractClass {

@Override
public void abstractMethod() {
    System.out.print("abstractMethod()");
}

}
`

Multiple Implementations of an Abstract Class:

`
public class SecondImplementingClass extends AbstractClass {

@Override
public void abstractMethod() {
    System.out.print("second abstractMethod()");
}

}
`

Dynamic Binding and Polymorphism:

Abstract classes allow dynamic binding, where objects of subclasses can be assigned to references of their parent abstract class. This enables polymorphism, allowing subclasses to behave in different ways while maintaining a consistent interface.

Restrictions and Limitations:

• Only one class inheritance is allowed.
• Interfaces, which are similar to abstract classes with only abstract methods, can be implemented along with abstract classes.
• Abstract methods cannot have method bodies and must be implemented by subclasses.
• Interface methods cannot be implemented, ensuring unique implementations in subclasses.

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