How does the automatic memory cleanup mechanism determine which objects are subject to deletion?

The automatic memory cleanup mechanism (Garbage Collector) in Java determines which objects are eligible for deletion based on their reachability. Objects are considered reachable if there is a reference to them from root objects, such as local variables in the stack, static fields, etc. If an object is unreachable, meaning there are no references to it, it is considered garbage and can be collected.

For example, if object A references object B, but no root object references A, then B is also considered unreachable because there is no chain of references from the roots to it.

Thus, the GC typically uses graph traversal algorithms, starting from the roots, and marks all reachable objects. All other objects are considered garbage and are eligible for collection.