# VolatileCallSite
Added in[API level 26](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
Summary:[Ctors](https://developer.android.com/reference/java/lang/invoke/VolatileCallSite#pubctors)\|[Methods](https://developer.android.com/reference/java/lang/invoke/VolatileCallSite#pubmethods)\|[Inherited Methods](https://developer.android.com/reference/java/lang/invoke/VolatileCallSite#inhmethods)
# VolatileCallSite
`
public
class
VolatileCallSite
`
`
``
extends `[CallSite](https://developer.android.com/reference/java/lang/invoke/CallSite)`
``
`
|---|---|-----------------------------------|
| [java.lang.Object](https://developer.android.com/reference/java/lang/Object) |||
| ↳ | [java.lang.invoke.CallSite](https://developer.android.com/reference/java/lang/invoke/CallSite) ||
| | ↳ | java.lang.invoke.VolatileCallSite |
*** ** * ** ***
A`VolatileCallSite`is a[CallSite](https://developer.android.com/reference/java/lang/invoke/CallSite)whose target acts like a volatile variable. An`invokedynamic`instruction linked to a`VolatileCallSite`sees updates to its call site target immediately, even if the update occurs in another thread. There may be a performance penalty for such tight coupling between threads.
In other respects, a`VolatileCallSite`is interchangeable with`MutableCallSite`.
**See also:**
- [MutableCallSite](https://developer.android.com/reference/java/lang/invoke/MutableCallSite)
## Summary
| ### Public constructors ||
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---|
| ` `[VolatileCallSite](https://developer.android.com/reference/java/lang/invoke/VolatileCallSite#VolatileCallSite(java.lang.invoke.MethodHandle))`(`[MethodHandle](https://developer.android.com/reference/java/lang/invoke/MethodHandle)` target) ` Creates a call site with a volatile binding to its target. |
| ` `[VolatileCallSite](https://developer.android.com/reference/java/lang/invoke/VolatileCallSite#VolatileCallSite(java.lang.invoke.MethodType))`(`[MethodType](https://developer.android.com/reference/java/lang/invoke/MethodType)` type) ` Creates a call site with a volatile binding to its target. |
| ### Public methods ||
|------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| ` final `[MethodHandle](https://developer.android.com/reference/java/lang/invoke/MethodHandle) | ` `[dynamicInvoker](https://developer.android.com/reference/java/lang/invoke/VolatileCallSite#dynamicInvoker())`() ` Produces a method handle equivalent to an invokedynamic instruction which has been linked to this call site. |
| ` final `[MethodHandle](https://developer.android.com/reference/java/lang/invoke/MethodHandle) | ` `[getTarget](https://developer.android.com/reference/java/lang/invoke/VolatileCallSite#getTarget())`() ` Returns the target method of the call site, which behaves like a`volatile`field of the`VolatileCallSite`. |
| ` void` | ` `[setTarget](https://developer.android.com/reference/java/lang/invoke/VolatileCallSite#setTarget(java.lang.invoke.MethodHandle))`(`[MethodHandle](https://developer.android.com/reference/java/lang/invoke/MethodHandle)` newTarget) ` Updates the target method of this call site, as a volatile variable. |
| ### Inherited methods |
|-----------------------|---|
| From class` `[java.lang.invoke.CallSite](https://developer.android.com/reference/java/lang/invoke/CallSite)` ` |---------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | ` abstract `[MethodHandle](https://developer.android.com/reference/java/lang/invoke/MethodHandle) | ` `[dynamicInvoker](https://developer.android.com/reference/java/lang/invoke/CallSite#dynamicInvoker())`() ` Produces a method handle equivalent to an invokedynamic instruction which has been linked to this call site. | | ` abstract `[MethodHandle](https://developer.android.com/reference/java/lang/invoke/MethodHandle) | ` `[getTarget](https://developer.android.com/reference/java/lang/invoke/CallSite#getTarget())`() ` Returns the target method of the call site, according to the behavior defined by this call site's specific class. | | ` abstract void` | ` `[setTarget](https://developer.android.com/reference/java/lang/invoke/CallSite#setTarget(java.lang.invoke.MethodHandle))`(`[MethodHandle](https://developer.android.com/reference/java/lang/invoke/MethodHandle)` newTarget) ` Updates the target method of this call site, according to the behavior defined by this call site's specific class. | | ` `[MethodType](https://developer.android.com/reference/java/lang/invoke/MethodType) | ` `[type](https://developer.android.com/reference/java/lang/invoke/CallSite#type())`() ` Returns the type of this call site's target. | ||
| From class` `[java.lang.Object](https://developer.android.com/reference/java/lang/Object)` ` |--------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | ` `[Object](https://developer.android.com/reference/java/lang/Object) | ` `[clone](https://developer.android.com/reference/java/lang/Object#clone())`() ` Creates and returns a copy of this object. | | ` boolean` | ` `[equals](https://developer.android.com/reference/java/lang/Object#equals(java.lang.Object))`(`[Object](https://developer.android.com/reference/java/lang/Object)` obj) ` Indicates whether some other object is "equal to" this one. | | ` void` | ` `[finalize](https://developer.android.com/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](https://developer.android.com/reference/java/lang/Class)`` | ` `[getClass](https://developer.android.com/reference/java/lang/Object#getClass())`() ` Returns the runtime class of this`Object`. | | ` int` | ` `[hashCode](https://developer.android.com/reference/java/lang/Object#hashCode())`() ` Returns a hash code value for the object. | | ` final void` | ` `[notify](https://developer.android.com/reference/java/lang/Object#notify())`() ` Wakes up a single thread that is waiting on this object's monitor. | | ` final void` | ` `[notifyAll](https://developer.android.com/reference/java/lang/Object#notifyAll())`() ` Wakes up all threads that are waiting on this object's monitor. | | ` `[String](https://developer.android.com/reference/java/lang/String) | ` `[toString](https://developer.android.com/reference/java/lang/Object#toString())`() ` Returns a string representation of the object. | | ` final void` | ` `[wait](https://developer.android.com/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](https://developer.android.com/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](https://developer.android.com/reference/java/lang/Object#wait())`() ` Causes the current thread to wait until it is awakened, typically by being*notified* or*interrupted*. | ||
## Public constructors
### VolatileCallSite
Added in[API level 26](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public VolatileCallSite (MethodHandle target)
```
Creates a call site with a volatile binding to its target. The target is set to the given value.
| Parameters ||
|----------|-------------------------------------------------------------------------------------------|
| `target` | `MethodHandle`: the method handle that will be the initial target of the call site
|
| Throws ||
|------------------------------------------------------------------------------------------------|--------------------------------|
| [NullPointerException](https://developer.android.com/reference/java/lang/NullPointerException) | if the proposed target is null |
### VolatileCallSite
Added in[API level 26](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public VolatileCallSite (MethodType type)
```
Creates a call site with a volatile binding to its target. The initial target is set to a method handle of the given type which will throw an`IllegalStateException`if called.
| Parameters ||
|--------|--------------------------------------------------------------------|
| `type` | `MethodType`: the method type that this call site will have
|
| Throws ||
|------------------------------------------------------------------------------------------------|------------------------------|
| [NullPointerException](https://developer.android.com/reference/java/lang/NullPointerException) | if the proposed type is null |
## Public methods
### dynamicInvoker
Added in[API level 26](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public final MethodHandle dynamicInvoker ()
```
Produces a method handle equivalent to an invokedynamic instruction which has been linked to this call site.
This method is equivalent to the following code:
>
> MethodHandle getTarget, invoker, result;
> getTarget = MethodHandles.publicLookup().bind(this, "getTarget", MethodType.methodType(MethodHandle.class));
> invoker = MethodHandles.exactInvoker(this.type());
> result = MethodHandles.foldArguments(invoker, getTarget)
>
| Returns ||
|---------------------------------------------------------------------------------------|-----------------------------------------------------------------------------|
| [MethodHandle](https://developer.android.com/reference/java/lang/invoke/MethodHandle) | a method handle which always invokes this call site's current target
|
### getTarget
Added in[API level 26](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public final MethodHandle getTarget ()
```
Returns the target method of the call site, which behaves like a`volatile`field of the`VolatileCallSite`.
The interactions of`getTarget`with memory are the same as of a read from a`volatile`field.
In particular, the current thread is required to issue a fresh read of the target from memory, and must not fail to see a recent update to the target by another thread.
| Returns ||
|---------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------|
| [MethodHandle](https://developer.android.com/reference/java/lang/invoke/MethodHandle) | the linkage state of this call site, a method handle which can change over time
|
**See also:**
- [setTarget(MethodHandle)](https://developer.android.com/reference/java/lang/invoke/VolatileCallSite#setTarget(java.lang.invoke.MethodHandle))
### setTarget
Added in[API level 26](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void setTarget (MethodHandle newTarget)
```
Updates the target method of this call site, as a volatile variable. The type of the new target must agree with the type of the old target.
The interactions with memory are the same as of a write to a volatile field. In particular, any threads is guaranteed to see the updated target the next time it calls`getTarget`.
| Parameters ||
|-------------|---------------------------------------|
| `newTarget` | `MethodHandle`: the new target
|
| Throws ||
|---------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------|
| [NullPointerException](https://developer.android.com/reference/java/lang/NullPointerException) | if the proposed new target is null |
| [WrongMethodTypeException](https://developer.android.com/reference/java/lang/invoke/WrongMethodTypeException) | if the proposed new target has a method type that differs from the previous target |
**See also:**
- [getTarget()](https://developer.android.com/reference/java/lang/invoke/VolatileCallSite#getTarget())