Lazily associate a computed value with any Class object. For example, if a dynamic language needs to construct a message dispatch table for each class encountered at a message send call site, it can use a ClassValue to cache information needed to perform the message send quickly, for each class encountered.

The basic operation of a ClassValue is get, which returns the associated value, initially created by an invocation to computeValue; multiple invocations may happen under race, but exactly one value is associated to a Class and returned.

Another operation is remove: it clears the associated value (if it exists), and ensures the next associated value is computed with input states up-to-date with the removal.

For a particular association, there is a total order for accesses to the associated value. Accesses are atomic; they include:

A read-only access by get
An attempt to associate the return value of a computeValue by get
Clearing of an association by remove

A get call always include at least one access; a remove call always has exactly one access; a computeValue call always happens between two accesses. This establishes the order of computeValue calls with respect to remove calls and determines whether the results of a computeValue can be successfully associated by a get.

Nested and Inner Type Summary

Modifier and Type	Class and Description
pack-priv static class	ClassValue.ClassValueMap A backing map for all ClassValues.
pack-priv static class	ClassValue.Entry<T> One binding of a value to a class via a ClassValue.
pack-priv static class	ClassValue.Identity Private key for retrieval of this object from ClassValueMap.
private static class	ClassValue.RemovalToken Besides a value (represented by an Entry), a "removal token" object, including the value `null`, can be present at a ClassValue-Class coordinate.
pack-priv static record	ClassValue.Version<T>

Field Summary

Modifier and Type	Field and Description
private static final Object	CRITICAL_SECTION
private static final ClassValue.Entry<?>[]	EMPTY_CACHE Initial, one-element, empty cache used by all Class instances.
private static final int	HASH_INCREMENT Good for power-of-two tables.
pack-priv static final int	HASH_MASK Mask a hash code to be positive but not too large, to prevent wraparound.
pack-priv final int	hashCodeForCache Internal hash code for accessing Class.classValueMap.cacheArray.
pack-priv final ClassValue.Identity	identity This ClassValue's identity, expressed as an opaque object.
private static final AtomicInteger	nextHashCode Value stream for hashCodeForCache.
private static final Unsafe	UNSAFE
private volatile ClassValue.Version<T>	version Current version for retrieving this class value from the cache.

Access	Constructor and Description
protected	ClassValue() Sole constructor.

Method Summary

Modifier and Type	Method and Description
pack-priv void	bumpVersion()
pack-priv ClassValue.Entry<T>	castEntry(ClassValue.Entry<?> e)
protected abstract T	Returns: the newly computed value to associate computeValue(Class<?> the `Class` to associate a value to type) Computes the value to associate to the given `Class`.
public T	Returns: the value associated to the given `Class` get(Class<?> the `Class` to retrieve the associated value for type) Returns the value associated to the given `Class`.
private static ClassValue.Entry<?>[]	getCacheCarefully(Class<?> type) Return the cache, if it exists, else a dummy empty cache.
private T	getFromBackup(ClassValue.Entry<?>[] cache, Class<?> type) Slow tail of ClassValue.get to retry at nearby locations in the cache, or take a slow lock and check the hash table.
private T	getFromHashMap(Class<?> type) Called when the fast path of get fails, and cache reprobe also fails.
private static ClassValue.ClassValueMap	getMap(Class<?> type) Return the backing map associated with this type.
private static ClassValue.ClassValueMap	initializeMap(Class<?> type)
pack-priv static <T> ClassValue.Entry<T>	makeEntry(ClassValue.Version<T> explicitVersion, T value)
pack-priv boolean	match(ClassValue.Entry<?> e) Check that e is non-null, matches this ClassValue, and is live.
pack-priv void	put(Class<?> type, T value)
public void	remove(Class<?> the type whose class value must be removed type) Removes the associated value for the given `Class` and invalidates all out-of-date computations.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

CRITICAL_SECTION	back to summary
private static final Object CRITICAL_SECTION

EMPTY_CACHE	back to summary
private static final ClassValue.Entry<?>[] EMPTY_CACHE Initial, one-element, empty cache used by all Class instances. Must never be filled.

HASH_INCREMENT	back to summary
private static final int HASH_INCREMENT Good for power-of-two tables. See similar structure in ThreadLocal.

HASH_MASK	back to summary
pack-priv static final int HASH_MASK Mask a hash code to be positive but not too large, to prevent wraparound.

hashCodeForCache	back to summary
pack-priv final int hashCodeForCache Internal hash code for accessing Class.classValueMap.cacheArray.

identity	back to summary
pack-priv final ClassValue.Identity identity This ClassValue's identity, expressed as an opaque object. The main object `ClassValue.this` is incorrect since subclasses may override `ClassValue.equals`, which could confuse keys in the ClassValueMap.

nextHashCode	back to summary
private static final AtomicInteger nextHashCode Value stream for hashCodeForCache. See similar structure in ThreadLocal.

UNSAFE	back to summary
private static final Unsafe UNSAFE

version	back to summary
private volatile ClassValue.Version<T> version Current version for retrieving this class value from the cache. Any number of computeValue calls can be cached in association with one version. But the version changes when a remove (on any type) is executed. A version change invalidates all cache entries for the affected ClassValue, by marking them as stale. Stale cache entries do not force another call to computeValue, but they do require a synchronized visit to a backing map. All user-visible state changes on the ClassValue take place under a lock inside the synchronized methods of ClassValueMap. Readers (of ClassValue.get) are notified of such state changes when this.version is bumped to a new token. This variable must be volatile so that an unsynchronized reader will receive the notification without delay. If version were not volatile, one thread T1 could persistently hold onto a stale value this.value == V1, while another thread T2 advances (under a lock) to this.value == V2. This will typically be harmless, but if T1 and T2 interact causally via some other channel, such that T1's further actions are constrained (in the JMM) to happen after the V2 event, then T1's observation of V1 will be an error. The practical effect of making this.version be volatile is that it cannot be hoisted out of a loop (by an optimizing JIT) or otherwise cached. Some machines may also require a barrier instruction to execute before this.version.

version

back to summary

private volatile ClassValue.Version<T> version

Current version for retrieving this class value from the cache. Any number of computeValue calls can be cached in association with one version. But the version changes when a remove (on any type) is executed. A version change invalidates all cache entries for the affected ClassValue, by marking them as stale. Stale cache entries do not force another call to computeValue, but they do require a synchronized visit to a backing map.

All user-visible state changes on the ClassValue take place under a lock inside the synchronized methods of ClassValueMap. Readers (of ClassValue.get) are notified of such state changes when this.version is bumped to a new token. This variable must be volatile so that an unsynchronized reader will receive the notification without delay.

If version were not volatile, one thread T1 could persistently hold onto a stale value this.value == V1, while another thread T2 advances (under a lock) to this.value == V2. This will typically be harmless, but if T1 and T2 interact causally via some other channel, such that T1's further actions are constrained (in the JMM) to happen after the V2 event, then T1's observation of V1 will be an error.

The practical effect of making this.version be volatile is that it cannot be hoisted out of a loop (by an optimizing JIT) or otherwise cached. Some machines may also require a barrier instruction to execute before this.version.

ClassValue	back to summary
protected ClassValue() Sole constructor. (For invocation by subclass constructors, typically implicit.)

Method Detail

bumpVersion	back to summary
pack-priv void bumpVersion()

castEntry	back to summary
pack-priv ClassValue.Entry<T> castEntry(ClassValue.Entry<?> e) Annotations @SuppressWarnings:unchecked

computeValue back to summary

computeValue	back to summary
protected abstract T computeValue(Class<?> type) Computes the value to associate to the given `Class`. This method is invoked when the initial read-only access by `get` finds no associated value. If this method throws an exception, the initiating `get` call will not attempt to associate a value, and may terminate by returning the associated value if it exists, or by propagating that exception otherwise. Otherwise, the value is computed and returned. An attempt to associate the return value happens, with one of the following outcomes: The associated value is present; it is returned and no association is done. The most recent `remove` call, if it exists, does not happen-before (JLS 17.4.5) the finish of the `computeValue` that computed the value to associate. A new invocation to `computeValue`, which that `remove` call happens-before, will re-establish this happens-before relationship. Otherwise, this value is successfully associated and returned. API Note A `computeValue` call may, due to class loading or other circumstances, recursively call `get` or `remove` for the same `type`. The recursive `get`, if the recursion stops, successfully finishes and this initiating `get` observes the associated value from recursion. The recursive `remove` is no-op, since being on the same thread, the `remove` already happens-before the finish of this `computeValue`; the result from this `computeValue` still may be associated. Parameters type:Class<?> the `Class` to associate a value to Returns:T the newly computed value to associate See Also `get`, `remove`

protected abstract T computeValue(Class<?> type)

Computes the value to associate to the given Class.

This method is invoked when the initial read-only access by get finds no associated value.

If this method throws an exception, the initiating get call will not attempt to associate a value, and may terminate by returning the associated value if it exists, or by propagating that exception otherwise.

Otherwise, the value is computed and returned. An attempt to associate the return value happens, with one of the following outcomes:

The associated value is present; it is returned and no association is done.
The most recent remove call, if it exists, does not happen-before (JLS 17.4.5) the finish of the computeValue that computed the value to associate. A new invocation to computeValue, which that remove call happens-before, will re-establish this happens-before relationship.
Otherwise, this value is successfully associated and returned.

API Note

A computeValue call may, due to class loading or other circumstances, recursively call get or remove for the same type. The recursive get, if the recursion stops, successfully finishes and this initiating get observes the associated value from recursion. The recursive remove is no-op, since being on the same thread, the remove already happens-before the finish of this computeValue; the result from this computeValue still may be associated.

Parameters

type:Class<?>: the Class to associate a value to

Returns:T

the newly computed value to associate

See Also

get, remove

get back to summary

get	back to summary
public T get(Class<?> type) Returns the value associated to the given `Class`. This method first performs a read-only access, and returns the associated value if it exists. Otherwise, this method tries to associate a value from a `computeValue` invocation until the associated value exists, which could be associated by a competing thread. This method may throw an exception from a `computeValue` invocation. In this case, no association happens. Parameters type:Class<?> the `Class` to retrieve the associated value for Returns:T the value associated to the given `Class` Exceptions NullPointerException: if the argument is `null` See Also `remove`, `computeValue`

public T get(Class<?> type)

Returns the value associated to the given Class.

This method first performs a read-only access, and returns the associated value if it exists. Otherwise, this method tries to associate a value from a computeValue invocation until the associated value exists, which could be associated by a competing thread.

This method may throw an exception from a computeValue invocation. In this case, no association happens.

Parameters

type:Class<?>: the Class to retrieve the associated value for

Returns:T

the value associated to the given Class

Exceptions

NullPointerException:: if the argument is null

See Also

remove, computeValue

getCacheCarefully	back to summary
private static ClassValue.Entry<?>[] getCacheCarefully(Class<?> type) Return the cache, if it exists, else a dummy empty cache.

getFromBackup	back to summary
private T getFromBackup(ClassValue.Entry<?>[] cache, Class<?> type) Slow tail of ClassValue.get to retry at nearby locations in the cache, or take a slow lock and check the hash table. Called only if the first probe was empty or a collision. This is a separate method, so compilers can process it independently.

getFromHashMap	back to summary
private T getFromHashMap(Class<?> type) Called when the fast path of get fails, and cache reprobe also fails.

getMap	back to summary
private static ClassValue.ClassValueMap getMap(Class<?> type) Return the backing map associated with this type.

initializeMap	back to summary
private static ClassValue.ClassValueMap initializeMap(Class<?> type)

makeEntry	back to summary
pack-priv static <T> ClassValue.Entry<T> makeEntry(ClassValue.Version<T> explicitVersion, T value)

match	back to summary
pack-priv boolean match(ClassValue.Entry<?> e) Check that e is non-null, matches this ClassValue, and is live.

put	back to summary
pack-priv void put(Class<?> type, T value)

remove back to summary

remove	back to summary
public void remove(Class<?> type) Removes the associated value for the given `Class` and invalidates all out-of-date computations. If this association is subsequently accessed, this removal happens-before (JLS 17.4.5) the finish of the `computeValue` call that returned the associated value. Parameters type:Class<?> the type whose class value must be removed Exceptions NullPointerException: if the argument is `null`

public void remove(Class<?> type)

Removes the associated value for the given Class and invalidates all out-of-date computations. If this association is subsequently accessed, this removal happens-before (JLS 17.4.5) the finish of the computeValue call that returned the associated value.

Parameters

type:Class<?>: the type whose class value must be removed

Exceptions

NullPointerException:: if the argument is null

java.lang back to summary

pack-priv final Class ClassValue.ClassValueMap

Class Inheritance

extends WeakHashMap<ClassValue.Identity, Object>

A backing map for all ClassValues. Gives a fully serialized "true state" for each pair (ClassValue cv, Class type). The state may be assigned value or unassigned token. Also manages an unserialized fast-path cache.

Field Summary

Modifier and Type	Field and Description
private static final int	CACHE_LOAD_LIMIT Percent loading of cache before resize.
private ClassValue.Entry<?>[]	cacheArray
private int	cacheLoad
private int	cacheLoadLimit
private static final int	INITIAL_ENTRIES Number of entries initially allocated to each type when first used with any ClassValue.
private static final int	PROBE_LIMIT Maximum number of probes to attempt.

Constructor Summary

Access	Constructor and Description
pack-priv	ClassValueMap() Build a backing map for ClassValues.

Method Summary

Modifier and Type	Method and Description
private <T> void	addToCache(ClassValue.Entry<T> e) Add the given entry to the cache, in its home location, unless it is out of date.
private <T> void	addToCache(ClassValue<T> classValue, ClassValue.Entry<T> e) Add the given entry to the cache, in its home location.
pack-priv synchronized <T> Object	associateAccess(ClassValue<T> classValue, ClassValue.RemovalToken startToken, T value)
private void	checkCacheLoad() Make sure the cache load stays below its limit, if possible.
private static int	entryDislocation(ClassValue.Entry<?>[] cache, int pos, ClassValue.Entry<?> e) How far out of place is e?
private ClassValue.Entry<?>	findReplacement(ClassValue.Entry<?>[] cache, int home1) Clearing a cache slot risks disconnecting following entries from the head of a non-null run, which would allow them to be found via reprobes.
pack-priv synchronized <T> void	forcedAssociateAccess(ClassValue<T> classValue, T value)
pack-priv ClassValue.Entry<?>[]	getCache()
pack-priv static ClassValue.Entry<?>	loadFromCache(ClassValue.Entry<?>[] cache, int i) Load the cache entry at the given (hashed) location.
private <T> ClassValue.Entry<T>	overwrittenEntry(ClassValue.Entry<T> e2) Note an entry that is about to be overwritten.
private ClassValue.Entry<?>	placeInCache(ClassValue.Entry<?>[] cache, int pos, ClassValue.Entry<?> e, boolean gently) Store the given entry.
pack-priv static <T> ClassValue.Entry<T>	probeBackupLocations(ClassValue.Entry<?>[] cache, ClassValue<T> classValue) Given that first probe was a collision, retry at nearby locations.
pack-priv static <T> ClassValue.Entry<T>	probeHomeLocation(ClassValue.Entry<?>[] cache, ClassValue<T> classValue) Look in the cache, at the home location for the given ClassValue.
pack-priv synchronized <T> Object	readAccess(ClassValue<T> classValue)
private void	reduceCacheLoad()
pack-priv synchronized void	removeAccess(ClassValue<?> classValue)
private void	removeStaleEntries(ClassValue.Entry<?>[] cache, int begin, int count) Remove stale entries in the given range.
private void	removeStaleEntries(ClassValue<?> classValue) Remove stale entries in the range near classValue.
private void	removeStaleEntries() Remove all stale entries, everywhere.
private void	sizeCache(int length) <hr> Below this line all functions are private, and assume synchronized access.

Inherited from java.util.WeakHashMap:: clear containsKey containsValue entrySet forEach get isEmpty keySet newWeakHashMap put putAll remove replaceAll size values

Field Detail

CACHE_LOAD_LIMIT	back to summary
private static final int CACHE_LOAD_LIMIT Percent loading of cache before resize.

cacheArray	back to summary
private ClassValue.Entry<?>[] cacheArray

cacheLoad	back to summary
private int cacheLoad

cacheLoadLimit	back to summary
private int cacheLoadLimit

INITIAL_ENTRIES	back to summary
private static final int INITIAL_ENTRIES Number of entries initially allocated to each type when first used with any ClassValue. It would be pointless to make this much smaller than the Class and ClassValueMap objects themselves. Must be a power of 2.

PROBE_LIMIT	back to summary
private static final int PROBE_LIMIT Maximum number of probes to attempt.

Constructor Detail

ClassValueMap	back to summary
pack-priv ClassValueMap() Build a backing map for ClassValues. Also, create an empty cache array and install it on the class.

Method Detail

addToCache	back to summary
private <T> void addToCache(ClassValue.Entry<T> e) Add the given entry to the cache, in its home location, unless it is out of date.

addToCache	back to summary
private <T> void addToCache(ClassValue<T> classValue, ClassValue.Entry<T> e) Add the given entry to the cache, in its home location.

associateAccess	back to summary
pack-priv synchronized <T> Object associateAccess(ClassValue<T> classValue, ClassValue.RemovalToken startToken, T value)

checkCacheLoad	back to summary
private void checkCacheLoad() Make sure the cache load stays below its limit, if possible.

entryDislocation	back to summary
private static int entryDislocation(ClassValue.Entry<?>[] cache, int pos, ClassValue.Entry<?> e) How far out of place is e?

findReplacement	back to summary
private ClassValue.Entry<?> findReplacement(ClassValue.Entry<?>[] cache, int home1) Clearing a cache slot risks disconnecting following entries from the head of a non-null run, which would allow them to be found via reprobes. Find an entry after cache[begin] to plug into the hole, or return null if none is needed.

forcedAssociateAccess	back to summary
pack-priv synchronized <T> void forcedAssociateAccess(ClassValue<T> classValue, T value)

getCache	back to summary
pack-priv ClassValue.Entry<?>[] getCache()

loadFromCache	back to summary
pack-priv static ClassValue.Entry<?> loadFromCache(ClassValue.Entry<?>[] cache, int i) Load the cache entry at the given (hashed) location.

overwrittenEntry	back to summary
private <T> ClassValue.Entry<T> overwrittenEntry(ClassValue.Entry<T> e2) Note an entry that is about to be overwritten. If it is not live, quietly replace it by null. If it is an actual null, increment cacheLoad, because the caller is going to store something in its place.

placeInCache	back to summary
private ClassValue.Entry<?> placeInCache(ClassValue.Entry<?>[] cache, int pos, ClassValue.Entry<?> e, boolean gently) Store the given entry. Update cacheLoad, and return any live victim. 'Gently' means return self rather than dislocating a live victim.

probeBackupLocations	back to summary
pack-priv static <T> ClassValue.Entry<T> probeBackupLocations(ClassValue.Entry<?>[] cache, ClassValue<T> classValue) Given that first probe was a collision, retry at nearby locations.

probeHomeLocation	back to summary
pack-priv static <T> ClassValue.Entry<T> probeHomeLocation(ClassValue.Entry<?>[] cache, ClassValue<T> classValue) Look in the cache, at the home location for the given ClassValue.

readAccess	back to summary
pack-priv synchronized <T> Object readAccess(ClassValue<T> classValue)

reduceCacheLoad	back to summary
private void reduceCacheLoad()

removeAccess	back to summary
pack-priv synchronized void removeAccess(ClassValue<?> classValue)

removeStaleEntries	back to summary
private void removeStaleEntries(ClassValue.Entry<?>[] cache, int begin, int count) Remove stale entries in the given range. Should be executed under a Map lock.

removeStaleEntries	back to summary
private void removeStaleEntries(ClassValue<?> classValue) Remove stale entries in the range near classValue.

removeStaleEntries	back to summary
private void removeStaleEntries() Remove all stale entries, everywhere.

sizeCache

back to summary

private void sizeCache(int length)

Below this line all functions are private, and assume synchronized access.

java.lang back to summary

pack-priv final Class ClassValue.Entry<T>

Class Inheritance

extends Object

java.lang.Object
java.lang.ClassValue.Entry

One binding of a value to a class via a ClassValue. Shared for the map and the cache array. The version is only meaningful for the cache array; whatever in the map is authentic, but state informs the cache an entry may be out-of-date. States are:

dead if version == null
stale if version != classValue.version
else live

Once an entry goes stale, it can be reset at any time into the dead state.

Field Summary

Modifier and Type	Field and Description
pack-priv static final ClassValue.Entry<?>	DEAD_ENTRY
pack-priv final T	value
pack-priv final WeakReference<ClassValue.Version<T>>	version

Constructor Summary

Access	Constructor and Description
pack-priv	Entry(ClassValue.Version<T> version, T value)

Method Summary

Modifier and Type	Method and Description
pack-priv ClassValue<T>	classValueOrNull()
pack-priv boolean	isLive()
pack-priv ClassValue.Entry<T>	refreshVersion(ClassValue.Version<T> v2)
pack-priv ClassValue.Version<T>	version()

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

DEAD_ENTRY	back to summary
pack-priv static final ClassValue.Entry<?> DEAD_ENTRY

value	back to summary
pack-priv final T value

version	back to summary
pack-priv final WeakReference<ClassValue.Version<T>> version

Constructor Detail

Entry	back to summary
pack-priv Entry(ClassValue.Version<T> version, T value)

Method Detail

classValueOrNull	back to summary
pack-priv ClassValue<T> classValueOrNull()

isLive	back to summary
pack-priv boolean isLive()

refreshVersion	back to summary
pack-priv ClassValue.Entry<T> refreshVersion(ClassValue.Version<T> v2)

version	back to summary
pack-priv ClassValue.Version<T> version()

java.lang back to summary

pack-priv Class ClassValue.Identity

Class Inheritance

extends Object

java.lang.Object
java.lang.ClassValue.Identity

Private key for retrieval of this object from ClassValueMap.

Constructor Summary

Access	Constructor and Description
pack-priv	Identity()

Method Summary

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Constructor Detail

Identity	back to summary
pack-priv Identity()

java.lang back to summary

private final Class ClassValue.RemovalToken

Class Inheritance

extends Object

java.lang.Object
java.lang.ClassValue.RemovalToken

Besides a value (represented by an Entry), a "removal token" object, including the value null, can be present at a ClassValue-Class coordinate. A removal token indicates whether the value from a computation is up-to-date; the value is up-to-date if the token is the same before and after computation (no removal during this period), or if the token is from the same thread (removed during computeValue). null is the initial state, meaning all computations are valid. Later tokens are always non-null, no matter if they replace existing entries or outdated tokens.

Field Summary

Modifier and Type	Field and Description
private final long	actorId

Constructor Summary

Access	Constructor and Description
private	RemovalToken()

Method Summary

Modifier and Type	Method and Description
private static boolean	allowsAssociation(ClassValue.RemovalToken current, ClassValue.RemovalToken start)

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

actorId	back to summary
private final long actorId

Constructor Detail

RemovalToken	back to summary
private RemovalToken()

Method Detail

allowsAssociation	back to summary
private static boolean allowsAssociation(ClassValue.RemovalToken current, ClassValue.RemovalToken start)

java.lang back to summary

pack-priv final Record ClassValue.Version<T>

Class Inheritance

extends Record

java.lang.Object
java.lang.Record
java.lang.ClassValue.Version

Record Components

classValue:ClassValue<T>

Field Summary

Modifier and Type	Field and Description
private final ClassValue<T>	classValue Record Component accessed by classValue().

Constructor Summary

Access	Constructor and Description
pack-priv	Version(ClassValue<T> classValue)

Method Summary

Modifier and Type	Method and Description
public ClassValue<T>	classValue() Record Component getter of classValue.
public final boolean	equals(Object o) Implements abstract java.lang.Record.equals. Indicates whether some other object is "equal to" this one.
public final int	hashCode() Implements abstract java.lang.Record.hashCode. Returns a hash code value for the record.
pack-priv boolean	isLive()
public final String	toString() Implements abstract java.lang.Record.toString. Returns a string representation of the record.

Field Detail

classValue	back to summary
private final ClassValue<T> classValue Record Component accessed by classValue().

Constructor Detail

Version	back to summary
pack-priv Version(ClassValue<T> classValue)

Method Detail

classValue	back to summary
public ClassValue<T> classValue() Record Component getter of classValue.

equals back to summary

public final boolean equals(Object o)

Implements abstract java.lang.Record.equals.

Doc from java.lang.Record.equals.

Indicates whether some other object is "equal to" this one. In addition to the general contract of Object.equals, record classes must further obey the invariant that when a record instance is "copied" by passing the result of the record component accessor methods to the canonical constructor, as follows:

    R copy = new R(r.c1(), r.c2(), ..., r.cn());

then it must be the case that r.equals(copy).

hashCode back to summary

public final int hashCode()

Implements abstract java.lang.Record.hashCode.

Doc from java.lang.Record.hashCode.

Returns a hash code value for the record. Obeys the general contract of Object.hashCode. For records, hashing behavior is constrained by the refined contract of Record.equals, so that any two records created from the same components must have the same hash code.

isLive	back to summary
pack-priv boolean isLive()

toString back to summary

public final String toString()

Implements abstract java.lang.Record.toString.

Doc from java.lang.Record.toString.

Returns a string representation of the record. In accordance with the general contract of Object#toString(), the toString method returns a string that "textually represents" this record. The result should be a concise but informative representation that is easy for a person to read.

In addition to this general contract, record classes must further participate in the invariant that any two records which are equal must produce equal strings. This invariant is necessarily relaxed in the rare case where corresponding equal component values might fail to produce equal strings for themselves.

public abstract Class ClassValue<T>

Nested and Inner Type Summary

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail

pack-priv final Class ClassValue.ClassValueMap

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail

Below this line all functions are private, and assume synchronized access.

pack-priv final Class ClassValue.Entry<T>

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail

pack-priv Class ClassValue.Identity

Constructor Summary

Method Summary

Constructor Detail

private final Class ClassValue.RemovalToken

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail

pack-priv final Record ClassValue.Version<T>

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail