Top Description Fields Constructors Methods
jdk.internal.util

pack-priv final Class WeakReferenceKey<T>

extends WeakReference<T>
implements ReferenceKey<T>
Class Inheritance
All Implemented Interfaces
jdk.internal.util.ReferenceKey
Type Parameters
<T>
key type
Imports
java.lang.ref.ReferenceQueue, .WeakReference, java.util.Objects

WeakReference wrapper key for entries in the backing map.
Since
21

Field Summary

Modifier and TypeField and Description
private final int
hashcode

Saved hashcode of the key.

Constructor Summary

AccessConstructor and Description
pack-priv
WeakReferenceKey(T
unwrapped key value
key
,
ReferenceQueue<T>
reference queue
queue
)

Package-Protected constructor.

Method Summary

Modifier and TypeMethod and Description
public boolean
equals(Object
the reference object with which to compare.
obj
)

Overrides java.lang.Object.equals.

Indicates whether some other object is "equal to" this one.

public int
hashCode()

Overrides java.lang.Object.hashCode.

Returns a hash code value for this object.

public String
toString()

Overrides java.lang.Object.toString.

Returns a string representation of the object.

public void
unused()

Implements jdk.internal.util.ReferenceKey.unused.

Cleanup unused key.

Field Detail

hashcodeback to summary
private final int hashcode

Saved hashcode of the key. Used when WeakReference is null.

Constructor Detail

WeakReferenceKeyback to summary
pack-priv WeakReferenceKey(T key, ReferenceQueue<T> queue)

Package-Protected constructor.

Parameters
key:T

unwrapped key value

queue:ReferenceQueue<T>

reference queue

Method Detail

equalsback to summary
public boolean equals(Object obj)

Overrides java.lang.Object.equals.

Doc from java.lang.Object.equals.

Indicates whether some other object is "equal to" this one.

The equals method implements an equivalence relation on non-null object references:

  • It is reflexive: for any non-null reference value x, x.equals(x) should return true.
  • It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
  • It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
  • It is consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.
  • For any non-null reference value x, x.equals(null) should return false.

An equivalence relation partitions the elements it operates on into equivalence classes; all the members of an equivalence class are equal to each other. Members of an equivalence class are substitutable for each other, at least for some purposes.

Parameters
obj:Object

the reference object with which to compare.

Returns:boolean

true if this object is the same as the obj argument; false otherwise.

Annotations
@Override
hashCodeback to summary
public int hashCode()

Overrides java.lang.Object.hashCode.

Doc from java.lang.Object.hashCode.

Returns a hash code value for this object. This method is supported for the benefit of hash tables such as those provided by java.util.HashMap.

The general contract of hashCode is:

  • Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
  • If two objects are equal according to the equals method, then calling the hashCode method on each of the two objects must produce the same integer result.
  • It is not required that if two objects are unequal according to the equals method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.
Returns:int

a hash code value for this object

Annotations
@Override
toStringback to summary
public String toString()

Overrides java.lang.Object.toString.

Doc from java.lang.Object.toString.

Returns a string representation of the object. Satisfying this method's contract implies a non-null result must be returned.

Returns:String

a string representation of the object

Annotations
@Override
unusedback to summary
public void unused()

Implements jdk.internal.util.ReferenceKey.unused.

Cleanup unused key. No need to enqueue since the key did not make it into the map.

Annotations
@Override