public abstract class Delegate extends Object
Two delegate instances that refer to the same named method are considered equal. Anonymous delegates are never considered equal to any other delegate.
Each subclass must provide an method named "invoke" that either directly contains the implementation (in the case of an anonymous delegate), or dispatches to a named instance or static method, passing parameters through and returning the result.
| Modifier | Constructor and Description |
|---|---|
protected |
Delegate()
Initializes an anonymous delegate with no external target or method.
|
protected |
Delegate(Class<?> targetClass,
String methodName,
Class<?>... methodParameterClasses)
Initializes a delegate that invokes the specified static method from the specified
class.
|
protected |
Delegate(Object targetObject,
String methodName,
Class<?>... methodParameterClasses)
Initializes a delegate that invokes the specified instance method on the specified
instance.
|
| Modifier and Type | Method and Description |
|---|---|
Object |
dynamicInvoke(Object... args)
Dynamically invokes (late-bound) the method represented by the current delegate.
|
boolean |
equals(Object obj)
Indicates whether some other object is "equal to" this one.
|
Method |
getMethod()
Gets the method represented by the delegate.
|
Object |
getTarget()
Gets the class instance on which the current delegate invokes the instance method.
|
int |
hashCode()
Returns a hash code value for the object.
|
protected Delegate()
Anonymous delegates are never considered equal to any other delegate.
protected Delegate(@Nonnull Class<?> targetClass, @Nonnull String methodName, @Nonnull Class<?>... methodParameterClasses)
Used to create a delegate for a static method.
targetClass - The class that defines the static method.methodName - The name of the static method that the delegate represents.methodParameterClasses - The classes of all method parameters, in order.protected Delegate(@Nonnull Object targetObject, @Nonnull String methodName, @Nonnull Class<?>... methodParameterClasses)
Used to create a delegate for an instance method.
targetObject - The instance on which the delegate will invoke the method.methodName - The name of the instance method that the delegate represents.methodParameterClasses - The classes of all method parameters.public Object dynamicInvoke(Object... args)
args - An array of objects that are the arguments to pass to the method
represented by the current delegate, or null, if the method represented
by the current delegate does not require arguments.@Nonnull public Method getMethod()
If this delegate invokes one or more methods, this returns the last method in the invocation list.
@Nullable public Object getTarget()
If this delegate invokes one or more instance methods, this returns the target of the last instance method in the invocation list.
public boolean equals(Object obj)
java.lang.Object
The equals method implements an equivalence relation
on non-null object references:
x, x.equals(x) should return
true.
x and y, x.equals(y)
should return true if and only if
y.equals(x) returns true.
x, y, and z, if
x.equals(y) returns true and
y.equals(z) returns true, then
x.equals(z) should return true.
x and y, multiple invocations of
x.equals(y) consistently return true
or consistently return false, provided no
information used in equals comparisons on the
objects is modified.
x,
x.equals(null) should return false.
The equals method for class Object implements
the most discriminating possible equivalence relation on objects;
that is, for any non-null reference values x and
y, this method returns true if and only
if x and y refer to the same object
(x == y has the value true).
Note that it is generally necessary to override the hashCode
method whenever this method is overridden, so as to maintain the
general contract for the hashCode method, which states
that equal objects must have equal hash codes.
equals in class Objectobj - the reference object with which to compare.true if this object is the same as the obj
argument; false otherwise.Object.hashCode(),
HashMappublic int hashCode()
java.lang.ObjectHashMap.
The general contract of hashCode is:
hashCode method
must consistently return the same integer, provided no information
used in equals comparisons on the object is modified.
This integer need not remain consistent from one execution of an
application to another execution of the same application.
equals(Object)
method, then calling the hashCode method on each of
the two objects must produce the same integer result.
Object.equals(java.lang.Object)
method, then calling the hashCode method on each of the
two objects must produce distinct integer results. However, the
programmer should be aware that producing distinct integer results
for unequal objects may improve the performance of hash tables.
As much as is reasonably practical, the hashCode method defined by
class Object does return distinct integers for distinct
objects. (This is typically implemented by converting the internal
address of the object into an integer, but this implementation
technique is not required by the
Java™ programming language.)
hashCode in class ObjectObject.equals(java.lang.Object),
System.identityHashCode(java.lang.Object)