How to prevent an object from getting garbage collected?

Question

How to prevent an object from getting garbage collected?

Are there any approaches by finalize or phantom reference or any other approaches?

I was asked this

Answer 1

I wonder if what they're going for is the pattern with resource pools (e.g. for network/db connections, or threads) where you use finalize to return a resource to the pool so that the actual object holding the resource isn't GC'ed.

Stupid example, in Java-like pseudocode and missing any kind of synchronization:

class SlowResourceInternal {
   private final SlowResourcePool parent;
   

   returnToPool() {
       parent.add(this);
   }
}

class SlowResourceHolder {
    private final SlowResourceInternal impl;

    

    finalize() {
        if (impl != null) impl.returnToPool();
    }
}