ReferenceQueue (Java SE 9 & JDK 9 ) (original) (raw)

• java.lang.Object

• • java.lang.ref.ReferenceQueue

• ---

public class ReferenceQueue
extends Object
Reference queues, to which registered reference objects are appended by the garbage collector after the appropriate reachability changes are detected.
Since:
1.2

• • Constructor Summary

  Constructors

  Constructor	Description
  ReferenceQueue​()	Constructs a new reference-object queue.

  • Method Summary

  All Methods Instance Methods Concrete Methods

  Modifier and Type	Method	Description
  Reference<? extends T>	poll​()	Polls this queue to see if a reference object is available.
  Reference<? extends T>	remove​()	Removes the next reference object in this queue, blocking until one becomes available.
  Reference<? extends T>	remove​(long timeout)	Removes the next reference object in this queue, blocking until either one becomes available or the given timeout period expires.

     * ### Methods inherited from class java.lang.[Object](../../../java/lang/Object.html "class in java.lang")  
     `[clone](../../../java/lang/Object.html#clone--), [equals](../../../java/lang/Object.html#equals-java.lang.Object-), [finalize](../../../java/lang/Object.html#finalize--), [getClass](../../../java/lang/Object.html#getClass--), [hashCode](../../../java/lang/Object.html#hashCode--), [notify](../../../java/lang/Object.html#notify--), [notifyAll](../../../java/lang/Object.html#notifyAll--), [toString](../../../java/lang/Object.html#toString--), [wait](../../../java/lang/Object.html#wait--), [wait](../../../java/lang/Object.html#wait-long-), [wait](../../../java/lang/Object.html#wait-long-int-)`

• • Constructor Detail

     * #### ReferenceQueue  
     public ReferenceQueue​()  
     Constructs a new reference-object queue.  

  • Method Detail

    * #### poll  
    public [Reference](../../../java/lang/ref/Reference.html "class in java.lang.ref")<? extends [T](../../../java/lang/ref/ReferenceQueue.html "type parameter in ReferenceQueue")> poll​()  
    Polls this queue to see if a reference object is available. If one is available without further delay then it is removed from the queue and returned. Otherwise this method immediately returns `null`.  
    Returns:  
    A reference object, if one was immediately available, otherwise `null`  
    * #### remove  
    public [Reference](../../../java/lang/ref/Reference.html "class in java.lang.ref")<? extends [T](../../../java/lang/ref/ReferenceQueue.html "type parameter in ReferenceQueue")> remove​(long timeout)  
                                  throws [IllegalArgumentException](../../../java/lang/IllegalArgumentException.html "class in java.lang"),  
                                         [InterruptedException](../../../java/lang/InterruptedException.html "class in java.lang")  
    Removes the next reference object in this queue, blocking until either one becomes available or the given timeout period expires.  
     This method does not offer real-time guarantees: It schedules the timeout as if by invoking the [Object.wait(long)](../../../java/lang/Object.html#wait-long-) method.  
    Parameters:  
    `timeout` \- If positive, block for up to `timeout` milliseconds while waiting for a reference to be added to this queue. If zero, block indefinitely.  
    Returns:  
    A reference object, if one was available within the specified timeout period, otherwise `null`  
    Throws:  
    `[IllegalArgumentException](../../../java/lang/IllegalArgumentException.html "class in java.lang")` \- If the value of the timeout argument is negative  
    `[InterruptedException](../../../java/lang/InterruptedException.html "class in java.lang")` \- If the timeout wait is interrupted  
    * #### remove  
    public [Reference](../../../java/lang/ref/Reference.html "class in java.lang.ref")<? extends [T](../../../java/lang/ref/ReferenceQueue.html "type parameter in ReferenceQueue")> remove​()  
                                  throws [InterruptedException](../../../java/lang/InterruptedException.html "class in java.lang")  
    Removes the next reference object in this queue, blocking until one becomes available.  
    Returns:  
    A reference object, blocking until one becomes available  
    Throws:  
    `[InterruptedException](../../../java/lang/InterruptedException.html "class in java.lang")` \- If the wait is interrupted

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