java.lang.ref.Reference Maven / Gradle / Ivy
/*
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stub files, must be accompanied by this notice in its entirety.
This work corresponds to the API signatures of JSR 219: Foundation
Profile 1.1. In the event of a discrepency between this work and the
JSR 219 specification, which is available at
http://www.jcp.org/en/jsr/detail?id=219, the latter takes precedence.
*/
package java.lang.ref;
/**
* Abstract base class for reference objects. This class defines the
* operations common to all reference objects. Because reference objects are
* implemented in close cooperation with the garbage collector, this class may
* not be subclassed directly.
*
* @version 1.35 08/27/01
* @author Mark Reinhold
* @since 1.2
*/
public abstract class Reference
{
Reference(Object referent) { }
Reference(Object referent, ReferenceQueue queue) { }
/**
* Returns this reference object's referent. If this reference object has
* been cleared, either by the program or by the garbage collector, then
* this method returns null.
*
* @return The object to which this reference refers, or
* null if this reference object has been cleared
*/
public Object get() {
return null;
}
/**
* Clears this reference object. Invoking this method will not cause this
* object to be enqueued.
*/
public void clear() { }
/**
* Tells whether or not this reference object has been enqueued, either by
* the program or by the garbage collector. If this reference object was
* not registered with a queue when it was created, then this method will
* always return false.
*
* @return true if and only if this reference object has
* been enqueued
*/
public boolean isEnqueued() {
return false;
}
/**
* Adds this reference object to the queue with which it is registered,
* if any.
*
* @return true if this reference object was successfully
* enqueued; false if it was already enqueued or if
* it was not registered with a queue when it was created
*/
public boolean enqueue() {
return false;
}
}