When Exactly Does Java's `finalize()` Method Get Called?

When Is Java's finalize() Method Invoked?

The finalize() method in Java plays a crucial role in the garbage collection process. However, it can be challenging to understand when this method is actually called.

Understanding Garbage Collection

Garbage collection in Java involves reclaiming memory space occupied by objects that are no longer in use. The JVM employs an algorithm to determine when objects become eligible for garbage collection.

Invocation of finalize()

The finalize() method is invoked when an object is about to be reclaimed by the garbage collector. However, it's important to note that the exact timing of this invocation is somewhat unpredictable.

Object eligibility for garbage collection does not immediately trigger the invocation of finalize(). The JVM may delay calling this method until a later garbage collection cycle or even not at all if the object becomes unreachable before the next cycle.

Test Class Behavior

In your test class, you have overridden the finalize() method to write to a file. If you're not observing this behavior, it could be because the object never reaches the point of eligibility for garbage collection or because no garbage collection cycle has occurred since the object became eligible.

Best Practices

While it's possible to force the JVM to run finalize on unfinalized objects, this is generally not advisable. Relying on finalize for proper application operation should be avoided.

Instead, the finalize() method should be used exclusively for cleanup tasks, particularly non-Java resource cleanup. The JVM's unpredictable behavior regarding finalize underscores this best practice.

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