java - What is the relationship between the PhantomReference and ReferenceQueue? -

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I'm a little confused about the phantom reference in Java when I saw in online articles that most of them have said That the Phantom Return object will return empty after creation, even though we get the reference () and also mentioned that the objects are accessible on the Fantamali, will be inserted into the context, when the Phantom reference will be removed,

I have tried the following code example, but I have confusion about the result. 

  device = tool (new); Reference queue queue = new reference qi (); Phantom Reference PR = New Phantom Reference (tool, queue); Println (pr.get ()); Println (queue.poll ());   
 Zero is printed above two statements. If pr.get () returns the tap, then does that mean that the garbage collected by the public is collected? If so, why is the object still not added to the priority queue?  
 Can someone help me clarify this thing?  
 Please describe these two words in the same way  
 Thanks a lot     
 
 
  
 
 The reference object referenced Returns because the context of a phantom reference is always unavailable, this method always produces blank.   
 You can not know whether it was collected or not  get () .  
 
 If so, why is the object still not added to the priority queue   
 state  
 
 if the garbage collector Determines at a fixed time that in the context of a phantom reference the phantom is accessible, then  then at that time or after some time  will reference this context.   
 So either this example was not collected by the  poll ()  (non-blocking) garbage or example garbage was collected, but FONTAM REFERENCE  was not added to  contextQuality  to set the strong context of related   null  and request for GC.  
, but also blocks  delete  at  context  from the queue.  
  device = null; Println (pr.get ()); System.gc (); Println (queue.remove ()); // Block and wait for it to be added

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