Invokable (Guava: Google Core Libraries for Java 17.0 API)

java.lang.Object
- java.lang.reflect.AccessibleObject
- - com.google.common.reflect.Invokable<T,R>

Type Parameters:
T - the type that owns this method or constructor.
R - the return type of (or supertype thereof) the method or the declaring type of the constructor.

All Implemented Interfaces:

AnnotatedElement, GenericDeclaration, Member
```
@Beta
public abstract class Invokable<T,R>
extends AccessibleObject
implements GenericDeclaration
```
Wrapper around either a Method or a Constructor. Convenience API is provided to make common reflective operation easier to deal with, such as isPublic(), getParameters() etc.
In addition to convenience methods, TypeToken.method(java.lang.reflect.Method) and TypeToken.constructor(java.lang.reflect.Constructor<?>) will resolve the type parameters of the method or constructor in the context of the owner type, which may be a subtype of the declaring class. For example:
```
   Method getMethod = List.class.getMethod("get", int.class);
   Invokable<List<String>, ?> invokable = new TypeToken<List<String>>() {}.method(getMethod);
   assertEquals(TypeToken.of(String.class), invokable.getReturnType()); // Not Object.class!
   assertEquals(new TypeToken<List<String>>() {}, invokable.getOwnerType());
```
Since:

14.0

Author:

Ben Yu

Field Summary
- Fields inherited from interface java.lang.reflect.Member
  DECLARED, PUBLIC

Method Summary

Methods
Modifier and Type	Method and Description
`boolean`	`equals(Object obj)` Indicates whether some other object is "equal to" this one.
`static <T> Invokable<T,T>`	`from(Constructor<T> constructor)` Returns `Invokable` of `constructor`.
`static Invokable<?,Object>`	`from(Method method)` Returns `Invokable` of `method`.
`<A extends Annotation> A`	`getAnnotation(Class<A> annotationClass)` Returns this element's annotation for the specified type if such an annotation is present, else null.
`Annotation[]`	`getAnnotations()` Returns all annotations present on this element.
`Annotation[]`	`getDeclaredAnnotations()` Returns all annotations that are directly present on this element.
`Class<? super T>`	`getDeclaringClass()` Returns the Class object representing the class or interface that declares the member or constructor represented by this Member.
`ImmutableList<TypeToken<? extends Throwable>>`	`getExceptionTypes()` Returns all declared exception types of this `Invokable`.
`int`	`getModifiers()` Returns the Java language modifiers for the member or constructor represented by this Member, as an integer.
`String`	`getName()` Returns the simple name of the underlying member or constructor represented by this Member.
`TypeToken<T>`	`getOwnerType()` Returns the type of `T`.
`ImmutableList<Parameter>`	`getParameters()` Returns all declared parameters of this `Invokable`.
`TypeToken<? extends R>`	`getReturnType()` Returns the return type of this `Invokable`.
`int`	`hashCode()` Returns a hash code value for the object.
`R`	`invoke(T receiver, Object... args)` Invokes with `receiver` as 'this' and `args` passed to the underlying method and returns the return value; or calls the underlying constructor with `args` and returns the constructed instance.
`boolean`	`isAbstract()` Returns true if the method is abstract.
`boolean`	`isAccessible()` Get the value of the `accessible` flag for this object.
`boolean`	`isAnnotationPresent(Class<? extends Annotation> annotationClass)` Returns true if an annotation for the specified type is present on this element, else false.
`boolean`	`isFinal()` Returns `true` if this method is final, per `Modifier.isFinal(getModifiers())`.
`boolean`	`isNative()` Returns true if the element is native.
`abstract boolean`	`isOverridable()` Returns `true` if this is an overridable method.
`boolean`	`isPackagePrivate()` Returns true if the element is package-private.
`boolean`	`isPrivate()` Returns true if the element is private.
`boolean`	`isProtected()` Returns true if the element is protected.
`boolean`	`isPublic()` Returns true if the element is public.
`boolean`	`isStatic()` Returns true if the element is static.
`boolean`	`isSynchronized()` Returns true if the method is synchronized.
`boolean`	`isSynthetic()` Returns `true` if this member was introduced by the compiler; returns `false` otherwise.
`abstract boolean`	`isVarArgs()` Returns `true` if this was declared to take a variable number of arguments.
`<R1 extends R> Invokable<T,R1>`	`returning(Class<R1> returnType)` Explicitly specifies the return type of this `Invokable`.
`<R1 extends R> Invokable<T,R1>`	`returning(TypeToken<R1> returnType)` Explicitly specifies the return type of this `Invokable`.
`void`	`setAccessible(boolean flag)` Set the `accessible` flag for this object to the indicated boolean value.
`String`	`toString()` Returns a string representation of the object.

Methods inherited from class java.lang.reflect.AccessibleObject
setAccessible

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.lang.reflect.GenericDeclaration
getTypeParameters

- Method Detail
  - from
```
public static Invokable<?,Object> from(Method method)
```
    Returns Invokable of method.
  - from
```
public static <T> Invokable<T,T> from(Constructor<T> constructor)
```
    Returns Invokable of constructor.
  - isOverridable
```
public abstract boolean isOverridable()
```
    Returns true if this is an overridable method. Constructors, private, static or final methods, or methods declared by final classes are not overridable.
  - isVarArgs
```
public abstract boolean isVarArgs()
```
    Returns true if this was declared to take a variable number of arguments.
  - invoke
```
public final R invoke(@Nullable
       T receiver,
       Object... args)
               throws InvocationTargetException,
                      IllegalAccessException
```
    Invokes with receiver as 'this' and args passed to the underlying method and returns the return value; or calls the underlying constructor with args and returns the constructed instance.
    
    Throws:
    
    IllegalAccessException - if this Constructor object enforces Java language access control and the underlying method or constructor is inaccessible.
    
    IllegalArgumentException - if the number of actual and formal parameters differ; if an unwrapping conversion for primitive arguments fails; or if, after possible unwrapping, a parameter value cannot be converted to the corresponding formal parameter type by a method invocation conversion.
    
    InvocationTargetException - if the underlying method or constructor throws an exception.
  - getReturnType
```
public final TypeToken<? extends R> getReturnType()
```
    Returns the return type of this Invokable.
  - getParameters
```
public final ImmutableList<Parameter> getParameters()
```
    Returns all declared parameters of this Invokable. Note that if this is a constructor of a non-static inner class, unlike Constructor.getParameterTypes(), the hidden this parameter of the enclosing class is excluded from the returned parameters.
  - getExceptionTypes
```
public final ImmutableList<TypeToken<? extends Throwable>> getExceptionTypes()
```
    Returns all declared exception types of this Invokable.
  - returning
```
public final <R1 extends R> Invokable<T,R1> returning(Class<R1> returnType)
```
    Explicitly specifies the return type of this Invokable. For example:
```
   Method factoryMethod = Person.class.getMethod("create");
   Invokable<?, Person> factory = Invokable.of(getNameMethod).returning(Person.class);
```
  - returning
```
public final <R1 extends R> Invokable<T,R1> returning(TypeToken<R1> returnType)
```
    Explicitly specifies the return type of this Invokable.
  - getDeclaringClass
```
public final Class<? super T> getDeclaringClass()
```
    Description copied from interface: java.lang.reflect.Member
    
    Returns the Class object representing the class or interface that declares the member or constructor represented by this Member.
    
    Specified by:
    
    getDeclaringClass in interface Member
    
    Returns:
    an object representing the declaring class of the underlying member
  - getOwnerType
```
public TypeToken<T> getOwnerType()
```
    Returns the type of T.
  - isAnnotationPresent
```
public final boolean isAnnotationPresent(Class<? extends Annotation> annotationClass)
```
    Description copied from interface: java.lang.reflect.AnnotatedElement
    
    Returns true if an annotation for the specified type is present on this element, else false. This method is designed primarily for convenient access to marker annotations.
    
    Specified by:
    
    isAnnotationPresent in interface AnnotatedElement
    
    Overrides:
    
    isAnnotationPresent in class AccessibleObject
    
    Parameters:
    annotationClass - the Class object corresponding to the annotation type
    
    Returns:
    true if an annotation for the specified annotation type is present on this element, else false
  - getAnnotation
```
public final <A extends Annotation> A getAnnotation(Class<A> annotationClass)
```
    Description copied from interface: java.lang.reflect.AnnotatedElement
    
    Returns this element's annotation for the specified type if such an annotation is present, else null.
    
    Specified by:
    
    getAnnotation in interface AnnotatedElement
    
    Overrides:
    
    getAnnotation in class AccessibleObject
    
    Parameters:
    annotationClass - the Class object corresponding to the annotation type
    
    Returns:
    this element's annotation for the specified annotation type if present on this element, else null
  - getAnnotations
```
public final Annotation[] getAnnotations()
```
    Description copied from interface: java.lang.reflect.AnnotatedElement
    
    Returns all annotations present on this element. (Returns an array of length zero if this element has no annotations.) The caller of this method is free to modify the returned array; it will have no effect on the arrays returned to other callers.
    
    Specified by:
    
    getAnnotations in interface AnnotatedElement
    
    Overrides:
    
    getAnnotations in class AccessibleObject
    
    Returns:
    all annotations present on this element
  - getDeclaredAnnotations
```
public final Annotation[] getDeclaredAnnotations()
```
    Description copied from interface: java.lang.reflect.AnnotatedElement
    
    Returns all annotations that are directly present on this element. Unlike the other methods in this interface, this method ignores inherited annotations. (Returns an array of length zero if no annotations are directly present on this element.) The caller of this method is free to modify the returned array; it will have no effect on the arrays returned to other callers.
    
    Specified by:
    
    getDeclaredAnnotations in interface AnnotatedElement
    
    Overrides:
    
    getDeclaredAnnotations in class AccessibleObject
    
    Returns:
    All annotations directly present on this element
  - setAccessible
```
public final void setAccessible(boolean flag)
                         throws SecurityException
```
    Description copied from class: java.lang.reflect.AccessibleObject
    
    Set the accessible flag for this object to the indicated boolean value. A value of true indicates that the reflected object should suppress Java language access checking when it is used. A value of false indicates that the reflected object should enforce Java language access checks.
    First, if there is a security manager, its checkPermission method is called with a ReflectPermission("suppressAccessChecks") permission.
    A SecurityException is raised if flag is true but accessibility of this object may not be changed (for example, if this element object is a Constructor object for the class Class).
    A SecurityException is raised if this object is a Constructor object for the class java.lang.Class, and flag is true.
    
    Overrides:
    
    setAccessible in class AccessibleObject
    
    Parameters:
    flag - the new value for the accessible flag
    
    Throws:
    
    SecurityException - if the request is denied.
    See Also:
    SecurityManager.checkPermission(java.security.Permission), RuntimePermission
  - isAccessible
```
public final boolean isAccessible()
```
    Description copied from class: java.lang.reflect.AccessibleObject
    
    Get the value of the accessible flag for this object.
    
    Overrides:
    
    isAccessible in class AccessibleObject
    
    Returns:
    the value of the object's accessible flag
  - getName
```
public final String getName()
```
    Description copied from interface: java.lang.reflect.Member
    
    Returns the simple name of the underlying member or constructor represented by this Member.
    
    Specified by:
    
    getName in interface Member
    
    Returns:
    the simple name of the underlying member
  - getModifiers
```
public final int getModifiers()
```
    Description copied from interface: java.lang.reflect.Member
    
    Returns the Java language modifiers for the member or constructor represented by this Member, as an integer. The Modifier class should be used to decode the modifiers in the integer.
    
    Specified by:
    
    getModifiers in interface Member
    
    Returns:
    the Java language modifiers for the underlying member
    See Also:
    Modifier
  - isSynthetic
```
public final boolean isSynthetic()
```
    Description copied from interface: java.lang.reflect.Member
    
    Returns true if this member was introduced by the compiler; returns false otherwise.
    
    Specified by:
    
    isSynthetic in interface Member
    
    Returns:
    true if and only if this member was introduced by the compiler.
  - isPublic
```
public final boolean isPublic()
```
    Returns true if the element is public.
  - isProtected
```
public final boolean isProtected()
```
    Returns true if the element is protected.
  - isPackagePrivate
```
public final boolean isPackagePrivate()
```
    Returns true if the element is package-private.
  - isPrivate
```
public final boolean isPrivate()
```
    Returns true if the element is private.
  - isStatic
```
public final boolean isStatic()
```
    Returns true if the element is static.
  - isFinal
```
public final boolean isFinal()
```
    Returns true if this method is final, per Modifier.isFinal(getModifiers()).
    Note that a method may still be effectively "final", or non-overridable when it has no final keyword. For example, it could be private, or it could be declared by a final class. To tell whether a method is overridable, use isOverridable().
  - isAbstract
```
public final boolean isAbstract()
```
    Returns true if the method is abstract.
  - isNative
```
public final boolean isNative()
```
    Returns true if the element is native.
  - isSynchronized
```
public final boolean isSynchronized()
```
    Returns true if the method is synchronized.
  - equals
```
public boolean equals(@Nullable
             Object obj)
```
    Description copied from class: java.lang.Object
    Indicates whether some other object is "equal to" this one.
    The equals method implements an equivalence relation on non-null object references:
    - It is reflexive: for any non-null reference value x, x.equals(x) should return true.
    - It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
    - It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
    - It is consistent: for any non-null reference values 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.
    - For any non-null reference value 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.
    Overrides:
    
    equals in class Object
    
    Parameters:
    obj - the reference object with which to compare.
    
    Returns:
    true if this object is the same as the obj argument; false otherwise.
    See Also:
    Object.hashCode(), HashMap
  - hashCode
```
public int hashCode()
```
    Description copied from class: java.lang.Object
    Returns a hash code value for the object. This method is supported for the benefit of hash tables such as those provided by HashMap.
    The general contract of hashCode is:
    - Whenever it is invoked on the same object more than once during an execution of a Java application, the 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.
    - If two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result.
    - It is not required that if two objects are unequal according to the 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^TM programming language.)
    Overrides:
    
    hashCode in class Object
    
    Returns:
    a hash code value for this object.
    See Also:
    Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)
  - toString
```
public String toString()
```
    Description copied from class: java.lang.Object
    Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.
    The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:
    getClass().getName() + '@' + Integer.toHexString(hashCode())
    Overrides:
    
    toString in class Object
    
    Returns:
    a string representation of the object.

Class Invokable<T,R>

Field Summary

Fields inherited from interface java.lang.reflect.Member

Method Summary

Methods inherited from class java.lang.reflect.AccessibleObject

Methods inherited from class java.lang.Object

Methods inherited from interface java.lang.reflect.GenericDeclaration

Method Detail

from

from

isOverridable

isVarArgs

invoke

getReturnType

getParameters

getExceptionTypes

returning

returning

getDeclaringClass

getOwnerType

isAnnotationPresent

getAnnotation

getAnnotations

getDeclaredAnnotations

setAccessible

isAccessible

getName

getModifiers

isSynthetic

isPublic

isProtected

isPackagePrivate

isPrivate

isStatic

isFinal

isAbstract

isNative

isSynchronized

equals

hashCode

toString