Class ConstantCallSite

java.lang.Object
java.lang.invoke.CallSite
java.lang.invoke.ConstantCallSite
public non-sealed class ConstantCallSite extends CallSite
A ConstantCallSite is a CallSite whose target is permanent, and can never be changed. An invokedynamic instruction linked to a ConstantCallSite is permanently bound to the call site's target.
Since:
1.7

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
     
    ConstantCallSite(MethodHandle target)
    Creates a call site with a permanent target.
    protected
    ConstantCallSite(MethodType targetType, MethodHandle createTargetHook)
    Creates a call site with a permanent target, possibly bound to the call site itself.

  • Method Summary

    Modifier and Type
    Method
    Description
    final MethodHandle
    dynamicInvoker()
    Returns this call site's permanent target.
    final MethodHandle
    getTarget()
    Returns the target method of the call site, which behaves like a final field of the ConstantCallSite.
    final void
    setTarget(MethodHandle ignore)
    Always throws an UnsupportedOperationException.

    Methods declared in class CallSite

    type
    Modifier and Type
    Method
    Description
    MethodType
    type()
    Returns the type of this call site's target.

    Methods declared in class Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    Modifier and Type
    Method
    Description
    protected Object
    clone()
    Creates and returns a copy of this object.
    boolean
    equals(Object obj)
    Indicates whether some other object is "equal to" this one.
    protected void
    finalize()
    Deprecated, for removal: This API element is subject to removal in a future version.
    Finalization is deprecated and subject to removal in a future release.
    final Class<?>
    getClass()
    Returns the runtime class of this Object.
    int
    hashCode()
    Returns a hash code value for this 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()
    Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
    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(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.

  • Constructor Details

    • ConstantCallSite

      public ConstantCallSite(MethodHandle target)
      Creates a call site with a permanent target.
      Parameters:
      target - the target to be permanently associated with this call site
      Throws:
      NullPointerException - if the proposed target is null

    • ConstantCallSite

      protected ConstantCallSite(MethodType targetType, MethodHandle createTargetHook) throws Throwable
      Creates a call site with a permanent target, possibly bound to the call site itself.

      During construction of the call site, the createTargetHook is invoked to produce the actual target, as if by a call of the form (MethodHandle) createTargetHook.invoke(this).

      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 someTarget.bindTo(this). 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 ConstantCallSite 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 IllegalStateException. It is legal at all times to obtain the call site's type using the type method.

      Parameters:
      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
      Throws:
      WrongMethodTypeException - if the hook cannot be invoked on the required arguments, or if the target returned by the hook is not of the given targetType
      NullPointerException - if the hook returns a null value
      ClassCastException - if the hook returns something other than a MethodHandle
      Throwable - anything else thrown by the hook function

  • Method Details