|Modifier||Constructor and Description|
Creates a call site with a permanent target.
Creates a call site with a permanent target, possibly bound to the call site itself.
|Modifier and Type||Method and Description|
Returns this call site's permanent target.
Returns the target method of the call site, which behaves like a
Always throws an
public ConstantCallSite(MethodHandle target)
target- the target to be permanently associated with this call site
NullPointerException- if the proposed target is null
protected ConstantCallSite(MethodType targetType, MethodHandle createTargetHook) throws Throwable
During construction of the call site, the
createTargetHook is invoked to
produce the actual target, as if by a call of the form
Note that user code cannot perform such an action directly in a subclass constructor,
since the target must be fixed before the
ConstantCallSite constructor returns.
The hook is said to bind the call site to a target method handle,
and a typical action would be
However, the hook is free to take any action whatever,
including ignoring the call site and returning a constant target.
The result returned by the hook must be a method handle of exactly the same type as the call site.
While the hook is being called, the new
object is in a partially constructed state.
In this state,
a call to
getTarget, or any other attempt to use the target,
will result in an
It is legal at all times to obtain the call site's type using the
targetType- the type of the method handle to be permanently associated with this call site
createTargetHook- a method handle to invoke (on the call site) to produce the call site's target
WrongMethodTypeException- if the hook cannot be invoked on the required arguments, or if the target returned by the hook is not of the given
NullPointerException- if the hook returns a null value
ClassCastException- if the hook returns something other than a
Throwable- anything else thrown by the the hook function
public final MethodHandle getTarget()
finalfield of the
ConstantCallSite. That is, the the target is always the original value passed to the constructor call which created this instance.
IllegalStateException- if the
ConstantCallSiteconstructor has not completed
public final void setTarget(MethodHandle ignore)
UnsupportedOperationException. This kind of call site cannot change its target.
ignore- a new target proposed for the call site, which is ignored
UnsupportedOperationException- because this kind of call site cannot change its target
public final MethodHandle dynamicInvoker()
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For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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