In Java object-oriented programming, what is an abstract method and how is it represented in a class or interface?

Introduction / Context:
An important concept in Java object-oriented programming is the idea of abstraction, where you define what an operation should do without specifying exactly how it is done. Abstract methods are a key language feature that support this idea. This question checks whether you can correctly identify what an abstract method is and how it appears in a class or interface definition.

Given Data / Assumptions:

• We are working in Java with classes and interfaces.
• Some classes are declared abstract because they are meant to be partially implemented base types.
• Interfaces define contracts that implementing classes must follow.
• The abstract keyword is available at the method level in abstract classes and is implied for methods in interfaces before Java 8.

Concept / Approach:
An abstract method is a method that specifies a signature (name, parameters, and possibly return type) but does not provide a body in that type. In an abstract class, you explicitly mark such a method using the abstract keyword and end the method header with a semicolon instead of a method body. In interfaces (prior to default and static methods), methods were implicitly abstract unless declared otherwise. Concrete subclasses or implementing classes must then provide the actual method body. This mechanism lets you define a general contract in a base type while deferring the details to specific implementations.

Step-by-Step Solution:
Step 1: Recall that a normal (concrete) method in Java has both a header and a body enclosed in curly braces.Step 2: Recognise that an abstract method is declared with the abstract keyword in an abstract class, has a method signature, and ends with a semicolon instead of a body.Step 3: Note that in interfaces, traditional methods are implicitly abstract unless declared as default or static, and also lack a body in older Java versions.Step 4: Understand that any non-abstract class that inherits an abstract method must implement it, otherwise the subclass must also be declared abstract.Step 5: Conclude that an abstract method represents a contract for behaviour, not a complete implementation, and therefore matches option A.

Verification / Alternative check:
You can verify this definition by writing a simple abstract class with an abstract method and attempting to instantiate it directly. The compiler prevents instantiation until a concrete subclass implements all abstract methods. Similarly, tools and documentation describe abstract methods as methods without bodies that must be implemented in subclasses, confirming the description in option A.

Why Other Options Are Wrong:
Option B confuses abstract methods with static final methods, which are fully implemented and cannot be overridden. Option C mislabels private methods, which can still have full bodies and are not abstract by default. Option D incorrectly suggests that the compiler generates abstract methods automatically for every class, which does not happen in Java. Only option A correctly captures the meaning and purpose of an abstract method.

Common Pitfalls:
A common pitfall is forgetting to declare the containing class as abstract when adding an abstract method, which leads to a compile-time error. Another mistake is assuming that interfaces cannot have any implemented methods; from Java 8 onwards, interfaces can include default and static methods with bodies, but traditional abstract methods still have no bodies. Keeping the distinction between abstract methods and concrete methods clear helps you design flexible, extensible hierarchies without confusion.

Final Answer:
Correct answer: A method declared with the abstract keyword that has no body in the declaring type and must be implemented by concrete subclasses or implementing classes