In Java, why and when should we override the finalize() method?

Introduction / Context:
The finalize() method is a legacy mechanism in Java that was originally intended to allow objects to clean up resources just before they are reclaimed by the garbage collector. Although its use is now discouraged in modern Java due to unpredictability and performance concerns, understanding its purpose remains important for reading older code and for interview questions. This question focuses on why and when finalize() might be overridden and what its practical limitations are.

Given Data / Assumptions:
- Every class inherits a finalize() method from java.lang.Object by default.
- The garbage collector manages memory for Java objects automatically, but some objects may hold non Java resources such as file handles or native memory.
- Modern alternatives such as try with resources, close() methods and reference queues exist.
- We are not required to override finalize() in everyday applications, but we need to understand its historical role.

Concept / Approach:
The idea behind finalize() is that the garbage collector, before reclaiming an object, might call its finalize() method once to allow last chance cleanup. In practice, this call is not guaranteed to happen in a timely manner or at all before program exit. Because of this unpredictability, using finalize() to release critical resources is considered bad practice. Instead, explicit resource management patterns such as implementing AutoCloseable and using try with resources are recommended. Overriding finalize() is now mainly of historical interest, and some Java versions even deprecate it.

Step-by-Step Solution:
Step 1: Recall that finalize() is inherited from Object and may be overridden in a subclass. Step 2: Understand that the intended purpose of finalize() is to clean up non memory resources such as open file descriptors or native handles during garbage collection. Step 3: Recognize that the garbage collector decides when or whether to call finalize(), so there is no guarantee about timing or even that it will be invoked. Step 4: Note that modern Java guidance strongly discourages relying on finalize() and instead advocates explicit close() methods and try with resources blocks. Step 5: Choose the option that explains this last chance cleanup purpose while acknowledging that explicit resource management is preferred.

Verification / Alternative check:
Consider a class that wraps a native resource. An older design might override finalize() to free the resource if the programmer forgot to call a close() method. However, if the JVM exits before the garbage collector runs or if the collector does not schedule finalization, the cleanup may never happen. This unreliability is why official documentation now advises against using finalize() for important cleanup. Therefore, while finalize() can be overridden for last chance cleanup, it should not be relied upon, which matches option A.

Why Other Options Are Wrong:
Option B incorrectly states that finalize() must be overridden in every class to allow main to execute, which is not true and not part of the Java specification.
Option C suggests that overriding finalize() prevents garbage collection, which is wrong; finalize() may delay collection but does not guarantee that objects remain in memory forever.
Option D claims that finalize() converts instance methods into static methods, which has no relation to the actual semantics of finalization.

Common Pitfalls:
A serious pitfall is relying on finalize() for critical work such as closing database connections or files, which can lead to resource leaks and unpredictable behavior under load. Finalizers can also create performance problems and introduce subtle concurrency issues. The recommended pattern is to provide explicit close methods, implement AutoCloseable where appropriate and use try with resources to ensure prompt cleanup. Understanding finalize() is useful mainly to avoid its misuse and to maintain legacy code that may still rely on it.

Final Answer:
The correct understanding is finalize() can be overridden to perform last chance cleanup of non Java resources before the garbage collector permanently removes an object, although modern best practice is to use explicit resource management instead.