T
- the class in which the constructor is declared
public final class Constructor<T> extends Executable
Constructor
provides information about, and access to, a single constructor for a class.
Constructor
permits widening conversions to occur when matching the actual parameters to newInstance() with the underlying constructor's formal parameters, but throws an IllegalArgumentException
if a narrowing conversion would occur.
Modifier and Type | Method and Description |
---|---|
boolean |
equals(Object
Compares this
Constructor against the specified object.
|
AnnotatedType |
getAnnotatedReceiverType()
Returns an
AnnotatedType object that represents the use of a type to specify the receiver type of the method/constructor represented by this Executable object.
|
AnnotatedType |
getAnnotatedReturnType()
Returns an
AnnotatedType object that represents the use of a type to specify the return type of the method/constructor represented by this Executable.
|
<T extends Annotation |
getAnnotation(Class
Returns this element's annotation for the specified type if such an annotation is
present, else null.
|
Annotation |
getDeclaredAnnotations()
Returns annotations that are
directly present on this element.
|
Class |
getDeclaringClass()
Returns the
Class object representing the class or interface that declares the executable represented by this object.
|
Class |
getExceptionTypes()
Returns an array of
Class objects that represent the types of exceptions declared to be thrown by the underlying executable represented by this object.
|
Type |
getGenericExceptionTypes()
Returns an array of
Type objects that represent the exceptions declared to be thrown by this executable object.
|
Type |
getGenericParameterTypes()
Returns an array of
Type objects that represent the formal parameter types, in declaration order, of the executable represented by this object.
|
int |
getModifiers()
Returns the Java language
modifiers for the executable represented by this object.
|
String |
getName()
Returns the name of this constructor, as a string.
|
Annotation |
getParameterAnnotations()
Returns an array of arrays of
Annotation s that represent the annotations on the formal parameters, in declaration order, of the
Executable represented by this object.
|
int |
getParameterCount()
Returns the number of formal parameters (whether explicitly declared or implicitly declared or neither) for the executable represented by this object.
|
Class |
getParameterTypes()
Returns an array of
Class objects that represent the formal parameter types, in declaration order, of the executable represented by this object.
|
TypeVariable |
getTypeParameters()
Returns an array of
TypeVariable objects that represent the type variables declared by the generic declaration represented by this
GenericDeclaration object, in declaration order.
|
int |
hashCode()
Returns a hashcode for this
Constructor .
|
boolean |
isSynthetic()
Returns
true if this executable is a synthetic construct; returns
false otherwise.
|
boolean |
isVarArgs()
Returns
true if this executable was declared to take a variable number of arguments; returns
false otherwise.
|
T |
newInstance(Object
Uses the constructor represented by this
Constructor object to create and initialize a new instance of the constructor's declaring class, with the specified initialization parameters.
|
String |
toGenericString()
Returns a string describing this
Constructor , including type parameters.
|
String |
toString()
Returns a string describing this
Constructor .
|
getAnnotatedExceptionTypes, getAnnotatedParameterTypes, getAnnotationsByType, getParameters
getAnnotations, getDeclaredAnnotation, getDeclaredAnnotationsByType, isAccessible, isAnnotationPresent, setAccessible, setAccessible
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
getAnnotations, getDeclaredAnnotation, getDeclaredAnnotationsByType, isAnnotationPresent
public Class<T> getDeclaringClass()
Class
object representing the class or interface that declares the executable represented by this object.
getDeclaringClass
in interface
Member
getDeclaringClass
in class
Executable
public StringgetName()
getName
in interface
Member
getName
in class
Executable
public int getModifiers()
getModifiers
in interface
Member
getModifiers
in class
Executable
Modifier
public TypeVariable<Constructor <T>>[] getTypeParameters()
TypeVariable
objects that represent the type variables declared by the generic declaration represented by this
GenericDeclaration
object, in declaration order. Returns an array of length 0 if the underlying generic declaration declares no type variables.
getTypeParameters
in interface
GenericDeclaration
getTypeParameters
in class
Executable
TypeVariable
objects that represent the type variables declared by this generic declaration
GenericSignatureFormatError
- if the generic signature of this generic declaration does not conform to the format specified in
The Java™ Virtual Machine Specification
public Class<?>[] getParameterTypes()
Class
objects that represent the formal parameter types, in declaration order, of the executable represented by this object. Returns an array of length 0 if the underlying executable takes no parameters.
getParameterTypes
in class
Executable
public int getParameterCount()
getParameterCount
in class
Executable
public Type[] getGenericParameterTypes()
Type
objects that represent the formal parameter types, in declaration order, of the executable represented by this object. Returns an array of length 0 if the underlying executable takes no parameters.
If a formal parameter type is a parameterized type, the Type
object returned for it must accurately reflect the actual type parameters used in the source code.
If a formal parameter type is a type variable or a parameterized type, it is created. Otherwise, it is resolved.
getGenericParameterTypes
in class
Executable
Type
s that represent the formal parameter types of the underlying executable, in declaration order
GenericSignatureFormatError
- if the generic method signature does not conform to the format specified in
The Java™ Virtual Machine Specification
TypeNotPresentException
- if any of the parameter types of the underlying executable refers to a non-existent type declaration
MalformedParameterizedTypeException
- if any of the underlying executable's parameter types refer to a parameterized type that cannot be instantiated for any reason
public Class<?>[] getExceptionTypes()
Class
objects that represent the types of exceptions declared to be thrown by the underlying executable represented by this object. Returns an array of length 0 if the executable declares no exceptions in its
throws
clause.
getExceptionTypes
in class
Executable
public Type[] getGenericExceptionTypes()
Type
objects that represent the exceptions declared to be thrown by this executable object. Returns an array of length 0 if the underlying executable declares no exceptions in its
throws
clause.
If an exception type is a type variable or a parameterized type, it is created. Otherwise, it is resolved.
getGenericExceptionTypes
in class
Executable
GenericSignatureFormatError
- if the generic method signature does not conform to the format specified in
The Java™ Virtual Machine Specification
TypeNotPresentException
- if the underlying executable's
throws
clause refers to a non-existent type declaration
MalformedParameterizedTypeException
- if the underlying executable's
throws
clause refers to a parameterized type that cannot be instantiated for any reason
public boolean equals(Objectobj)
Constructor
against the specified object. Returns true if the objects are the same. Two
Constructor
objects are the same if they were declared by the same class and have the same formal parameter types.
equals
in class
Object
obj
- the reference object with which to compare.
true
if this object is the same as the obj argument;
false
otherwise.
Object.hashCode()
,
HashMap
public int hashCode()
Constructor
. The hashcode is the same as the hashcode for the underlying constructor's declaring class name.
hashCode
in class
Object
Object.equals(java.lang.Object)
,
System.identityHashCode(java.lang.Object)
public StringtoString()
Constructor
. The string is formatted as the constructor access modifiers, if any, followed by the fully-qualified name of the declaring class, followed by a parenthesized, comma-separated list of the constructor's formal parameter types. For example:
public java.util.Hashtable(int,float)
The only possible modifiers for constructors are the access modifiers public
, protected
or private
. Only one of these may appear, or none if the constructor has default (package) access.
public StringtoGenericString()
Constructor
, including type parameters. The string is formatted as the constructor access modifiers, if any, followed by an angle-bracketed comma separated list of the constructor's type parameters, if any, followed by the fully-qualified name of the declaring class, followed by a parenthesized, comma-separated list of the constructor's generic formal parameter types. If this constructor was declared to take a variable number of arguments, instead of denoting the last parameter as "
Type[]", it is denoted as "
Type...". A space is used to separate access modifiers from one another and from the type parameters or return type. If there are no type parameters, the type parameter list is elided; if the type parameter list is present, a space separates the list from the class name. If the constructor is declared to throw exceptions, the parameter list is followed by a space, followed by the word "
throws
" followed by a comma-separated list of the thrown exception types.
The only possible modifiers for constructors are the access modifiers public
, protected
or private
. Only one of these may appear, or none if the constructor has default (package) access.
toGenericString
in class
Executable
Constructor
, include type parameters
public T newInstance(Object... initargs) throws InstantiationException , IllegalAccessException , IllegalArgumentException , InvocationTargetException
Constructor
object to create and initialize a new instance of the constructor's declaring class, with the specified initialization parameters. Individual parameters are automatically unwrapped to match primitive formal parameters, and both primitive and reference parameters are subject to method invocation conversions as necessary.
If the number of formal parameters required by the underlying constructor is 0, the supplied initargs
array may be of length 0 or null.
If the constructor's declaring class is an inner class in a non-static context, the first argument to the constructor needs to be the enclosing instance; see section 15.9.3 of The Java™ Language Specification.
If the required access and argument checks succeed and the instantiation will proceed, the constructor's declaring class is initialized if it has not already been initialized.
If the constructor completes normally, returns the newly created and initialized instance.
initargs
- array of objects to be passed as arguments to the constructor call; values of primitive types are wrapped in a wrapper object of the appropriate type (e.g. a
float
in a
Float
)
IllegalAccessException
- if this
Constructor
object is enforcing Java language access control and the underlying 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; if this constructor pertains to an enum type.
InstantiationException
- if the class that declares the underlying constructor represents an abstract class.
InvocationTargetException
- if the underlying constructor throws an exception.
ExceptionInInitializerError
- if the initialization provoked by this method fails.
public boolean isVarArgs()
true
if this executable was declared to take a variable number of arguments; returns
false
otherwise.
isVarArgs
in class
Executable
true
if an only if this executable was declared to take a variable number of arguments.
public boolean isSynthetic()
true
if this executable is a synthetic construct; returns
false
otherwise.
isSynthetic
in interface
Member
isSynthetic
in class
Executable
public <T extends Annotation> T getAnnotation(Class <T> annotationClass)
getAnnotation
in interface
AnnotatedElement
getAnnotation
in class
Executable
T
- the type of the annotation to query for and return if present
annotationClass
- the Class object corresponding to the annotation type
NullPointerException
- if the given annotation class is null
public Annotation[] getDeclaredAnnotations()
getDeclaredAnnotations
in interface
AnnotatedElement
getDeclaredAnnotations
in class
Executable
public Annotation[][] getParameterAnnotations()
Annotation
s that represent the annotations on the formal parameters, in declaration order, of the
Executable
represented by this object. Synthetic and mandated parameters (see explanation below), such as the outer "this" parameter to an inner class constructor will be represented in the returned array. If the executable has no parameters (meaning no formal, no synthetic, and no mandated parameters), a zero-length array will be returned. If the
Executable
has one or more parameters, a nested array of length zero is returned for each parameter with no annotations. The annotation objects contained in the returned arrays are serializable. The caller of this method is free to modify the returned arrays; it will have no effect on the arrays returned to other callers. A compiler may add extra parameters that are implicitly declared in source ("mandated"), as well as parameters that are neither implicitly nor explicitly declared in source ("synthetic") to the parameter list for a method. See
Parameter
for more information.
getParameterAnnotations
in class
Executable
Parameter
,
Parameter.getAnnotations()
public AnnotatedTypegetAnnotatedReturnType()
AnnotatedType
object that represents the use of a type to specify the return type of the method/constructor represented by this Executable. If this
Executable
object represents a constructor, the
AnnotatedType
object represents the type of the constructed object. If this
Executable
object represents a method, the
AnnotatedType
object represents the use of a type to specify the return type of the method.
getAnnotatedReturnType
in class
Executable
Executable
public AnnotatedTypegetAnnotatedReceiverType()
AnnotatedType
object that represents the use of a type to specify the receiver type of the method/constructor represented by this Executable object. The receiver type of a method/constructor is available only if the method/constructor has a
receiver parameter (JLS 8.4.1). If this
Executable
object represents a constructor or instance method that does not have a receiver parameter, or has a receiver parameter with no annotations on its type, then the return value is an
AnnotatedType
object representing an element with no annotations. If this
Executable
object represents a static method, then the return value is null.
getAnnotatedReceiverType
in class
Executable
Executable