How does Java solve retain cycles in garbage collection?

Question

I know that a retain cycle (at least in Objective-C and Swift) is when two objects claim ownership of one another (they have references to each other). And in Objective-C we can

Answer 1

The garbage collector looks for reachable objects, starting from the roots (typically: variables on the call stack or global variables). So if two objects reference each other but are not otherwise reachable they won't be flagged as "live" and will be collected.