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Added in API level 1

Constructor

public final class Constructor
extends AccessibleObject implements GenericDeclaration, Member

java.lang.Object
↳	java.lang.reflect.AccessibleObject
	↳	java.lang.reflect.Constructor<T>

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:

Summary

Inherited constants

From interface


    java.lang.reflect.Member

Fields
`protected int`	`accessFlags` Bits encoding access (e.g.
`protected Class<?>`	`declaringClass` Method's declaring class
`protected Class<?>`	`declaringClassOfOverriddenMethod` Overriden method's declaring class (same as declaringClass unless declaringClass is a proxy class)
`protected int`	`dexMethodIndex` The method index of this method within its defining dex file

Public methods
`boolean`	`equals(Object obj)` Compares this `Constructor` against the specified object.
`<T extends Annotation> T`	`getAnnotation(Class<T> annotationClass)` Returns this element's annotation for the specified type if such an annotation is present, else null.
`<A extends Annotation> A`	`getAnnotation(Class<A> annotationType)` 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<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`	`isAnnotationPresent(Class<? extends Annotation> annotationType)`
`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... args)` 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`.

Protected methods
`int`	`compareParameters(Class[]<?> params)`
`boolean`	`equalMethodParameters(Class[]<?> params)`

Inherited methods

From class


  
    java.lang.reflect.AccessibleObject

From class


  
    java.lang.Object

`Object`	`clone()` Creates and returns a copy of this object.
`boolean`	`equals(Object obj)` Indicates whether some other object is "equal to" this one.
`void`	`finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`final Class<?>`	`getClass()` Returns the runtime class of this `Object`.
`int`	`hashCode()` Returns a hash code value for the object.
`final void`	`notify()` Wakes up a single thread that is waiting on this object's monitor.
`final void`	`notifyAll()` Wakes up all threads that are waiting on this object's monitor.
`String`	`toString()` Returns a string representation of the object.
`final void`	`wait(long millis, int nanos)` Causes the current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object, or some other thread interrupts the current thread, or a certain amount of real time has elapsed.
`final void`	`wait(long millis)` Causes the current thread to wait until either another thread invokes the `notify()` method or the `notifyAll()` method for this object, or a specified amount of time has elapsed.
`final void`	`wait()` Causes the current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object.

From interface


  
    java.lang.reflect.AnnotatedElement

`abstract <T extends Annotation> T`	`getAnnotation(Class<T> annotationClass)` Returns this element's annotation for the specified type if such an annotation is present, else null.
`abstract Annotation[]`	`getAnnotations()` Returns all annotations present on this element.
`default <T extends Annotation> T[]`	`getAnnotationsByType(Class<T> annotationClass)` Returns an associated list of annotations on `this` element, whose class is `annotationClass`, or an empty array if nothing was found.
`default <T extends Annotation> Annotation`	`getDeclaredAnnotation(Class<T> annotationClass)` Returns a directly-present annotation on `this` element, whose class is `annotationClass`, or `null` if nothing was found.
`abstract Annotation[]`	`getDeclaredAnnotations()` Returns all annotations that are directly present on this element.
`default <T extends Annotation> T[]`	`getDeclaredAnnotationsByType(Class<T> annotationClass)` Returns a directly or indirectly present list of annotations on `this` element, whose class is `annotationClass`, or an empty array if nothing was found.
`default boolean`	`isAnnotationPresent(Class<? extends Annotation> annotationClass)` Returns true if an annotation for the specified type is present on this element, else false.

From interface


  
    java.lang.reflect.GenericDeclaration

From interface


  
    java.lang.reflect.Member

Fields

accessFlags

int accessFlags

Bits encoding access (e.g. public, private) as well as other runtime specific flags

declaringClass

Class<?> declaringClass

Method's declaring class

declaringClassOfOverriddenMethod

Class<?> declaringClassOfOverriddenMethod

Overriden method's declaring class (same as declaringClass unless declaringClass is a proxy class)

dexMethodIndex

int dexMethodIndex

The method index of this method within its defining dex file

Public methods

equals

Added in API level 1

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.

Parameters
`obj`	`Object`: the reference object with which to compare.

Returns
`boolean`	`true` if this object is the same as the obj argument; `false` otherwise.

getAnnotation

Added in API level 1

T getAnnotation (Class<T> annotationClass)

Returns this element's annotation for the specified type if such an annotation is present, else null.

Parameters
`annotationClass`	`Class`: the Class object corresponding to the annotation type

Returns
`T`	this element's annotation for the specified annotation type if present on this element, else null

getAnnotation

Added in API level 14

A getAnnotation (Class<A> annotationType)

Returns this element's annotation for the specified type if such an annotation is present, else null.

Parameters
`annotationType`	`Class`: the Class object corresponding to the annotation type

Returns
`A`	this element's annotation for the specified annotation type if present on this element, else null

Throws
`NullPointerException`

getAnnotations

Added in API level 1

Annotation[] getAnnotations ()

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.

Returns
`Annotation[]`	all annotations present on this element

getDeclaredAnnotations

Added in API level 1

Annotation[] getDeclaredAnnotations ()

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.

Returns
`Annotation[]`	All annotations directly present on this element

getDeclaringClass

Added in API level 1

Class<T> getDeclaringClass ()

Returns the Class object representing the class that declares the constructor represented by this Constructor object.

Returns
`Class<T>`

getExceptionTypes

Added in API level 1

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
`Class[]<?>`	the exception types declared as being thrown by the constructor this object represents

getGenericExceptionTypes

Added in API level 1

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 type variable or a parameterized type, it is created. Otherwise, it is resolved.

Returns
`Type[]`	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
`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

getGenericParameterTypes

Added in API level 1

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
`Type[]`	an array of `Type`s 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
`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

getModifiers

Added in API level 1

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.

Returns
`int`

See also:

Modifier

getName

Added in API level 1

String getName ()

Returns the name of this constructor, as a string. This is the binary name of the constructor's declaring class.

Returns
`String`	the name of this method

getParameterAnnotations

Added in API level 1

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
`Annotation[][]`	an array of arrays that represent the annotations on the formal parameters, in declaration order, of the method represented by this Constructor object

getParameterTypes

Added in API level 1

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
`Class[]<?>`	the parameter types for the constructor this object represents

getTypeParameters

Added in API level 1

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.

Returns
`TypeVariable[]<Constructor<T>>`	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

hashCode

Added in API level 1

int hashCode ()

Returns a hashcode for this Constructor. The hashcode is the same as the hashcode for the underlying constructor's declaring class name.

Returns
`int`	a hash code value for this object.

isAnnotationPresent

Added in API level 1

boolean isAnnotationPresent (Class<? extends Annotation> annotationType)

Parameters
`annotationType`	`Class`

Returns
`boolean`

isSynthetic

Added in API level 1

boolean isSynthetic ()

Returns true if this constructor is a synthetic constructor; returns false otherwise.

Returns
`boolean`	true if and only if this constructor is a synthetic constructor as defined by The Java™ Language Specification.

isVarArgs

Added in API level 1

boolean isVarArgs ()

Returns true if this constructor was declared to take a variable number of arguments; returns false otherwise.

Returns
`boolean`	`true` if an only if this constructor was declared to take a variable number of arguments.

newInstance

Added in API level 1

T newInstance (Object... args)

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 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.

Parameters
`args`	`Object`: 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
`T`	a new object created by calling the constructor this object represents

Throws
`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.

toGenericString

Added in API level 1

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. 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.

Returns
`String`	a string describing this `Constructor`, include type parameters

toString

Added in API level 1

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.

Returns
`String`	a string representation of the object.

Protected methods

compareParameters

int compareParameters (Class[]<?> params)

Parameters
`params`	`Class`

Returns
`int`

equalMethodParameters

boolean equalMethodParameters (Class[]<?> params)

Parameters
`params`	`Class`

Returns
`boolean`