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InheritableThreadLocal
public
class
InheritableThreadLocal
extends ThreadLocal<T>
This class extends ThreadLocal to provide inheritance of values
from parent thread to child thread: when a child thread is created, the
child receives initial values for all inheritable thread-local variables
for which the parent has values. Normally the child's values will be
identical to the parent's; however, the child's value can be made an
arbitrary function of the parent's by overriding the childValue
method in this class.
Inheritable thread-local variables are used in preference to
ordinary thread-local variables when the per-thread-attribute being
maintained in the variable (e.g., User ID, Transaction ID) must be
automatically transmitted to any child threads that are created.
Note: During the creation of a new thread, it is
possible to opt out of receiving initial values for inheritable
thread-local variables.
Summary
Protected methods |
|---|
T
|
childValue(T parentValue)
Computes the child's initial value for this inheritable thread-local
variable as a function of the parent's value at the time the child
thread is created.
|
Inherited methods |
|---|
From class
java.lang.ThreadLocal
T
|
get()
Returns the value in the current thread's copy of this
thread-local variable.
|
T
|
initialValue()
Returns the current thread's "initial value" for this
thread-local variable.
|
void
|
remove()
Removes the current thread's value for this thread-local
variable.
|
void
|
set(T value)
Sets the current thread's copy of this thread-local variable
to the specified value.
|
static
<S>
ThreadLocal<S>
|
withInitial(Supplier<? extends S> supplier)
Creates a thread local variable.
|
|
From class
java.lang.Object
Object
|
clone()
Creates and returns a copy of this object.
|
boolean
|
equals(Object obj)
Indicates whether some other object is "equal to" this one.
|
void
|
finalize()
Called by the garbage collector on an object when garbage collection
determines that there are no more references to the object.
|
final
Class<?>
|
getClass()
Returns the runtime class of this Object.
|
int
|
hashCode()
Returns a hash code value for the object.
|
final
void
|
notify()
Wakes up a single thread that is waiting on this object's
monitor.
|
final
void
|
notifyAll()
Wakes up all threads that are waiting on this object's monitor.
|
String
|
toString()
Returns a string representation of the object.
|
final
void
|
wait(long timeoutMillis, int nanos)
Causes the current thread to wait until it is awakened, typically
by being notified or interrupted, or until a
certain amount of real time has elapsed.
|
final
void
|
wait(long timeoutMillis)
Causes the current thread to wait until it is awakened, typically
by being notified or interrupted, or until a
certain amount of real time has elapsed.
|
final
void
|
wait()
Causes the current thread to wait until it is awakened, typically
by being notified or interrupted.
|
|
Public constructors
InheritableThreadLocal
public InheritableThreadLocal ()
Creates an inheritable thread local variable.
Protected methods
childValue
protected T childValue (T parentValue)
Computes the child's initial value for this inheritable thread-local
variable as a function of the parent's value at the time the child
thread is created. This method is called from within the parent
thread before the child is started.
This method merely returns its input argument, and should be overridden
if a different behavior is desired.
| Parameters |
|---|
parentValue |
T: the parent thread's value |
| Returns |
|---|
T |
the child thread's initial value |
Content and code samples on this page are subject to the licenses described in the Content License. Java and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.
Last updated 2025-08-20 UTC.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-20 UTC."],[],[],null,["# InheritableThreadLocal\n\nAdded in [API level 1](/guide/topics/manifest/uses-sdk-element#ApiLevels) \nSummary: [Ctors](#pubctors) \\| [Protected Methods](#promethods) \\| [Inherited Methods](#inhmethods) \n\nInheritableThreadLocal\n======================\n\n\n`\npublic\n\n\nclass\nInheritableThreadLocal\n`\n\n\n`\n\n\n`\n\n`\n\nextends `[ThreadLocal](/reference/java/lang/ThreadLocal)`\u003cT\u003e\n\n\n`\n\n`\n\n\n`\n\n|---|---|---------------------------------------|\n| [java.lang.Object](/reference/java/lang/Object) |||\n| ↳ | [java.lang.ThreadLocal](/reference/java/lang/ThreadLocal)\\\u003cT\\\u003e ||\n| | ↳ | java.lang.InheritableThreadLocal\\\u003cT\\\u003e |\n\n\u003cbr /\u003e\n\n*** ** * ** ***\n\nThis class extends `ThreadLocal` to provide inheritance of values\nfrom parent thread to child thread: when a child thread is created, the\nchild receives initial values for all inheritable thread-local variables\nfor which the parent has values. Normally the child's values will be\nidentical to the parent's; however, the child's value can be made an\narbitrary function of the parent's by overriding the `childValue`\nmethod in this class.\n\nInheritable thread-local variables are used in preference to\nordinary thread-local variables when the per-thread-attribute being\nmaintained in the variable (e.g., User ID, Transaction ID) must be\nautomatically transmitted to any child threads that are created.\n\nNote: During the creation of a new [thread](/reference/java/lang/Thread#Thread(java.lang.ThreadGroup,%20java.lang.Runnable,%20java.lang.String,%20long,%20boolean)), it is\npossible to *opt out* of receiving initial values for inheritable\nthread-local variables. \n**See also:**\n\n- [ThreadLocal](/reference/java/lang/ThreadLocal)\n\nSummary\n-------\n\n| ### Public constructors ||\n|------------------------------------------------------------------------------------------------------------------------------------------------------|---|\n| ` `[InheritableThreadLocal](/reference/java/lang/InheritableThreadLocal#InheritableThreadLocal())`() ` Creates an inheritable thread local variable. |\n\n| ### Protected methods ||\n|------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|\n| ` T` | ` `[childValue](/reference/java/lang/InheritableThreadLocal#childValue(T))`(T parentValue) ` Computes the child's initial value for this inheritable thread-local variable as a function of the parent's value at the time the child thread is created. |\n\n| ### Inherited methods |\n|-----------------------|---|\n| From class ` `[java.lang.ThreadLocal](/reference/java/lang/ThreadLocal)` ` |--------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | ` T` | ` `[get](/reference/java/lang/ThreadLocal#get())`() ` Returns the value in the current thread's copy of this thread-local variable. | | ` T` | ` `[initialValue](/reference/java/lang/ThreadLocal#initialValue())`() ` Returns the current thread's \"initial value\" for this thread-local variable. | | ` void` | ` `[remove](/reference/java/lang/ThreadLocal#remove())`() ` Removes the current thread's value for this thread-local variable. | | ` void` | ` `[set](/reference/java/lang/ThreadLocal#set(T))`(T value) ` Sets the current thread's copy of this thread-local variable to the specified value. | | ` static \u003cS\u003e `[ThreadLocal](/reference/java/lang/ThreadLocal)`\u003cS\u003e` | ` `[withInitial](/reference/java/lang/ThreadLocal#withInitial(java.util.function.Supplier\u003c?%20extends%20S\u003e))`(`[Supplier](/reference/java/util/function/Supplier)`\u003c? extends S\u003e supplier) ` Creates a thread local variable. | ||\n| From class ` `[java.lang.Object](/reference/java/lang/Object)` ` |---------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | ` `[Object](/reference/java/lang/Object) | ` `[clone](/reference/java/lang/Object#clone())`() ` Creates and returns a copy of this object. | | ` boolean` | ` `[equals](/reference/java/lang/Object#equals(java.lang.Object))`(`[Object](/reference/java/lang/Object)` obj) ` Indicates whether some other object is \"equal to\" this one. | | ` void` | ` `[finalize](/reference/java/lang/Object#finalize())`() ` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. | | ` final `[Class](/reference/java/lang/Class)`\u003c?\u003e` | ` `[getClass](/reference/java/lang/Object#getClass())`() ` Returns the runtime class of this `Object`. | | ` int` | ` `[hashCode](/reference/java/lang/Object#hashCode())`() ` Returns a hash code value for the object. | | ` final void` | ` `[notify](/reference/java/lang/Object#notify())`() ` Wakes up a single thread that is waiting on this object's monitor. | | ` final void` | ` `[notifyAll](/reference/java/lang/Object#notifyAll())`() ` Wakes up all threads that are waiting on this object's monitor. | | ` `[String](/reference/java/lang/String) | ` `[toString](/reference/java/lang/Object#toString())`() ` Returns a string representation of the object. | | ` final void` | ` `[wait](/reference/java/lang/Object#wait(long,%20int))`(long timeoutMillis, int nanos) ` Causes the current thread to wait until it is awakened, typically by being *notified* or *interrupted*, or until a certain amount of real time has elapsed. | | ` final void` | ` `[wait](/reference/java/lang/Object#wait(long))`(long timeoutMillis) ` Causes the current thread to wait until it is awakened, typically by being *notified* or *interrupted*, or until a certain amount of real time has elapsed. | | ` final void` | ` `[wait](/reference/java/lang/Object#wait())`() ` Causes the current thread to wait until it is awakened, typically by being *notified* or *interrupted*. | ||\n\nPublic constructors\n-------------------\n\n### InheritableThreadLocal\n\nAdded in [API level 1](/guide/topics/manifest/uses-sdk-element#ApiLevels) \n\n```\npublic InheritableThreadLocal ()\n```\n\nCreates an inheritable thread local variable.\n\n\u003cbr /\u003e\n\nProtected methods\n-----------------\n\n### childValue\n\nAdded in [API level 1](/guide/topics/manifest/uses-sdk-element#ApiLevels) \n\n```\nprotected T childValue (T parentValue)\n```\n\nComputes the child's initial value for this inheritable thread-local\nvariable as a function of the parent's value at the time the child\nthread is created. This method is called from within the parent\nthread before the child is started.\n\n\nThis method merely returns its input argument, and should be overridden\nif a different behavior is desired.\n\n\u003cbr /\u003e\n\n| Parameters ||\n|---------------|---------------------------------------|\n| `parentValue` | `T`: the parent thread's value \u003cbr /\u003e |\n\n| Returns ||\n|-----|-----------------------------------------|\n| `T` | the child thread's initial value \u003cbr /\u003e |"]]
