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()
    Answers a new instance of the same class as the receiver, whose slots have been filled in with the values in the slots of the receiver.
    boolean
    equals(Object o)
    Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison.
    protected void
    finalize()
    Deprecated, for removal: This API element is subject to removal in a future version.
    May cause performance issues, deadlocks and hangs.
    final Class<? extends Object>
    getClass()
    Answers the unique instance of java.lang.Class which represents the class of the receiver.
    int
    hashCode()
    Answers an integer hash code for the receiver.
    final void
    notify()
    Causes one thread which is waiting on the receiver to be made ready to run.
    final void
    notifyAll()
    Causes all threads which are waiting on the receiver to be made ready to run.
    String
    toString()
    Answers a string containing a concise, human-readable description of the receiver.
    final void
    wait()
    Causes the thread which sent this message to be made not ready to run pending some change in the receiver (as indicated by notify or notifyAll).
    final void
    wait(long time)
    Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by notify or notifyAll) or the expiration of the timeout.
    final void
    wait(long time, int frac)
    Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by notify or notifyAll) or the expiration of the timeout.

  • 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