In object oriented Java programming, what is inheritance and how does it allow one class to reuse another class's behavior?

Introduction / Context:
Inheritance is a foundational concept in object oriented programming and is heavily used in Java to create class hierarchies. Interviewers often ask this question to ensure that you understand how code reuse, specialization, and generalization work in Java. Knowing inheritance well also helps when you work with frameworks and libraries that provide base classes and abstract classes for you to extend.

Given Data / Assumptions:

• We are working with Java classes and interfaces.
• There is at least one base class, sometimes called a parent or superclass.
• There is at least one derived class, also called a child or subclass.
• The subclass should be able to reuse and possibly extend the behavior of the superclass.

Concept / Approach:
Inheritance allows one class to inherit fields and methods from another class. In Java, this is expressed using the extends keyword for classes and implements for interfaces. The subclass automatically acquires the non private data members and methods of the superclass and can also add its own specific behavior. This creates an “is a” relationship, for example a Dog is an Animal. Inheritance supports code reuse and makes the system easier to maintain by centralizing common logic in a base class.

Step-by-Step Solution:
1. Define a superclass such as Animal with common fields and methods like name and makeSound(). 2. Create a subclass such as Dog that extends Animal using the syntax class Dog extends Animal. 3. The Dog class automatically inherits the non private fields and methods from Animal. 4. Dog can override methods such as makeSound() to provide a more specific implementation, for example printing "Bark". 5. Dog can also add new methods that are not present in Animal, thereby extending the behavior.

Verification / Alternative check:
You can verify an inheritance relationship using the “is a” test. If Dog is a type of Animal, then Dog should extend Animal. If Car is a type of Vehicle, then Car should extend Vehicle. If the relationship is more like “has a,” such as a Car has an Engine, then composition is more appropriate than inheritance. Correct use of inheritance leads to intuitive hierarchies and makes unit testing and maintenance easier.

Why Other Options Are Wrong:
Option B describes method overloading, where multiple methods in the same class share a name but have different parameter lists. Option C describes polymorphism, where the same interface or superclass reference can refer to objects of different subclasses. Option D is related to Java's platform independence, which is achieved by bytecode and the JVM, not by inheritance itself.

Common Pitfalls:
One common pitfall is overusing inheritance where composition would be better, causing rigid, tightly coupled hierarchies. Another issue is violating the Liskov Substitution Principle, where a subclass does not behave like its superclass, breaking expectations. Developers also sometimes use inheritance only to reuse code without considering whether the conceptual “is a” relationship truly exists. Good Java design uses inheritance when it reflects real conceptual relationships and helps maintainability.

Final Answer:
Inheritance allows a class to acquire properties and behaviors from another class, promoting code reuse and hierarchical relationships.