| JavaTM 2 Platform Std. Ed. v1.6.0
java.lang.reflect
Class Constructor<T>
java.lang.Object
 java.lang.reflect.AccessibleObject
java.lang.reflect.Constructor<T>
- Type Parameters:
T - the class in which the constructor is declared
- All Implemented Interfaces:
- AnnotatedElement, GenericDeclaration, Member
public final class Constructor<T> - extends AccessibleObject
- implements GenericDeclaration, Member
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.
- See Also:
Member,
Class,
Class.getConstructors(),
Class.getConstructor(Class[]),
Class.getDeclaredConstructors()
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Method Summary |
boolean |
equals(Object obj)
Compares this Constructor against the specified object. |
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getAnnotation(Class<T> annotationClass)
Returns this element's annotation for the specified type if
such an annotation is present, else null. |
Annotation[] |
getDeclaredAnnotations()
Returns all annotations that are directly present on this
element. |
Class<T> |
getDeclaringClass()
Returns the Class object representing the class that declares
the constructor represented by this Constructor object. |
Class<?>[] |
getExceptionTypes()
Returns an array of Class objects that represent the types
of exceptions declared to be thrown by the underlying constructor
represented by this Constructor object. |
Type[] |
getGenericExceptionTypes()
Returns an array of Type objects that represent the
exceptions declared to be thrown by this Constructor object. |
Type[] |
getGenericParameterTypes()
Returns an array of Type objects that represent the formal
parameter types, in declaration order, of the method represented by
this Constructor object. |
int |
getModifiers()
Returns the Java language modifiers for the constructor
represented by this Constructor object, as an integer. |
String |
getName()
Returns the name of this constructor, as a string. |
Annotation[][] |
getParameterAnnotations()
Returns an array of arrays that represent the annotations on the formal
parameters, in declaration order, of the method represented by
this Constructor object. |
Class<?>[] |
getParameterTypes()
Returns an array of Class objects that represent the formal
parameter types, in declaration order, of the constructor
represented by this Constructor object. |
TypeVariable<Constructor<T>>[] |
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 constructor is a synthetic
constructor; returns false otherwise. |
boolean |
isVarArgs()
Returns true if this constructor was declared to take
a variable number of arguments; returns false
otherwise. |
T |
newInstance(Object... initargs)
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. |
getDeclaringClass
public Class<T> getDeclaringClass()
- Returns the
Class object representing the class that declares
the constructor represented by this Constructor object.
- Specified by:
getDeclaringClass in interface Member
- Returns:
- an object representing the declaring class of the
underlying member
getName
public String getName()
- Returns the name of this constructor, as a string. This is
always the same as the simple name of the constructor's declaring
class.
- Specified by:
getName in interface Member
- Returns:
- the simple name of the underlying member
getModifiers
public int getModifiers()
- Returns the Java language modifiers for the constructor
represented by this
Constructor object, as an integer. The
Modifier class should be used to decode the modifiers.
- Specified by:
getModifiers in interface Member
- Returns:
- the Java language modifiers for the underlying member
- See Also:
Modifier
getTypeParameters
public TypeVariable<Constructor<T>>[] 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. Returns an
array of length 0 if the underlying generic declaration declares no type
variables.
- Specified by:
getTypeParameters in interface GenericDeclaration
- Returns:
- an array of TypeVariable objects that represent
the type variables declared by this generic declaration
- Throws:
GenericSignatureFormatError - if the generic
signature of this generic declaration does not conform to
the format specified in the Java Virtual Machine Specification,
3rd edition- Since:
- 1.5
getParameterTypes
public Class<?>[] getParameterTypes()
- Returns an array of
Class objects that represent the formal
parameter types, in declaration order, of the constructor
represented by this Constructor object. Returns an array of
length 0 if the underlying constructor takes no parameters.
- Returns:
- the parameter types for the constructor this object
represents
getGenericParameterTypes
public Type[] getGenericParameterTypes()
- Returns an array of Type objects that represent the formal
parameter types, in declaration order, of the method represented by
this Constructor object. Returns an array of length 0 if the
underlying method 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.
- Returns:
- an array of Types that represent the formal
parameter types of the underlying method, in declaration order
- Throws:
GenericSignatureFormatError - if the generic method signature does not conform to the format
specified in the Java Virtual Machine Specification, 3rd edition
TypeNotPresentException - if any of the parameter
types of the underlying method refers to a non-existent type
declaration
MalformedParameterizedTypeException - if any of
the underlying method's parameter types refer to a parameterized
type that cannot be instantiated for any reason- Since:
- 1.5
getExceptionTypes
public Class<?>[] getExceptionTypes()
- Returns an array of
Class objects that represent the types
of exceptions declared to be thrown by the underlying constructor
represented by this Constructor object. Returns an array of
length 0 if the constructor declares no exceptions in its throws clause.
- Returns:
- the exception types declared as being thrown by the
constructor this object represents
getGenericExceptionTypes
public Type[] getGenericExceptionTypes()
- Returns an array of Type objects that represent the
exceptions declared to be thrown by this Constructor object.
Returns an array of length 0 if the underlying method declares
no exceptions in its throws clause.
If an exception type is a parameterized type, the Type
object returned for it must accurately reflect the actual type
parameters used in the source code.
If an exception type is a type variable or a parameterized
type, it is created. Otherwise, it is resolved.
- Returns:
- an array of Types that represent the exception types
thrown by the underlying method
- Throws:
GenericSignatureFormatError - if the generic method signature does not conform to the format
specified in the Java Virtual Machine Specification, 3rd edition
TypeNotPresentException - if the underlying method's
throws clause refers to a non-existent type declaration
MalformedParameterizedTypeException - if
the underlying method's throws clause refers to a
parameterized type that cannot be instantiated for any reason- Since:
- 1.5
equals
public boolean equals(Object obj)
- Compares this
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.
- 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(),
Hashtable
hashCode
public int hashCode()
- Returns a hashcode for this
Constructor. The hashcode is
the same as the hashcode for the underlying constructor's
declaring class name.
- Overrides:
hashCode in class Object
- Returns:
- a hash code value for this object.
- See Also:
Object.equals(java.lang.Object),
Hashtable
toString
public String toString()
- Returns a string describing this
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.
- Overrides:
toString in class Object
- Returns:
- a string representation of the object.
toGenericString
public String toGenericString()
- Returns a string describing this
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. 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.
- Returns:
- a string describing this
Constructor,
include type parameters - Since:
- 1.5
newInstance
public T newInstance(Object... initargs)
throws InstantiationException,
IllegalAccessException,
IllegalArgumentException,
InvocationTargetException
- 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.
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 The Java Language
Specification, section 15.9.3.
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.
- Parameters:
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)
- Returns:
- a new object created by calling the constructor
this object represents
- Throws:
IllegalAccessException - if this Constructor object
enforces 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.
isVarArgs
public boolean isVarArgs()
- Returns true if this constructor was declared to take
a variable number of arguments; returns false
otherwise.
- Returns:
- true if an only if this constructor was declared to
take a variable number of arguments.
- Since:
- 1.5
isSynthetic
public boolean isSynthetic()
- Returns true if this constructor is a synthetic
constructor; returns false otherwise.
- Specified by:
isSynthetic in interface Member
- Returns:
- true if and only if this constructor is a synthetic
constructor as defined by the Java Language Specification.
- Since:
- 1.5
getAnnotation
public <T extends Annotation> T getAnnotation(Class<T> annotationClass)
- Description copied from interface:
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
- Throws:
NullPointerException - if the given annotation class is null- Since:
- 1.5
getDeclaredAnnotations
public Annotation[] getDeclaredAnnotations()
- Description copied from interface:
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
- Since:
- 1.5
getParameterAnnotations
public Annotation[][] getParameterAnnotations()
- Returns an array of arrays that represent the annotations on the formal
parameters, in declaration order, of the method represented by
this Constructor object. (Returns an array of length zero if the
underlying method is parameterless. If the method 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.
- Returns:
- an array of arrays that represent the annotations on the formal
parameters, in declaration order, of the method represented by this
Constructor object
- Since:
- 1.5
Copyright 2003 Sun Microsystems, Inc. All rights reserved
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