Two objects refer to each other, but no one else refers to them. Will the garbage collector find them?

Yes, the garbage collector in Java will find such objects and free their memory.

The garbage collector works based on object reachability: if an object is unreachable from root references (for example, from the stack, static variables, etc.), it is considered garbage, even if objects reference each other.

In your case, two objects reference each other, but no one else references them from outside — meaning they are unreachable from the roots and will be collected by the garbage collector.