Constructor (Java SE 10 & JDK 10 ) (original) (raw)
Method Detail
* #### setAccessible
public void setAccessible(boolean flag)
Set the `accessible` flag for this reflected object to the indicated boolean value. A value of `true` indicates that the reflected object should suppress checks for Java language access control when it is used. A value of `false` indicates that the reflected object should enforce checks for Java language access control when it is used, with the variation noted in the class description.
This method may be used by a caller in class `C` to enable access to a [member](../../../java/lang/reflect/Member.html "interface in java.lang.reflect") of [declaring class](../../../java/lang/reflect/Member.html#getDeclaringClass%28%29) `D` if any of the following hold:
* `C` and `D` are in the same module.
* The member is `public` and `D` is `public` in a package that the module containing `D` [exports](../../../java/lang/Module.html#isExported%28java.lang.String,java.lang.Module%29) to at least the module containing `C`.
* The member is `protected` `static`, `D` is`public` in a package that the module containing `D` exports to at least the module containing `C`, and `C` is a subclass of `D`.
* `D` is in a package that the module containing `D` [opens](../../../java/lang/Module.html#isOpen%28java.lang.String,java.lang.Module%29) to at least the module containing `C`. All packages in unnamed and open modules are open to all modules and so this method always succeeds when `D` is in an unnamed or open module.
This method cannot be used to enable access to private members, members with default (package) access, protected instance members, or protected constructors when the declaring class is in a different module to the caller and the package containing the declaring class is not open to the caller's module.
If there is a security manager, its`checkPermission` method is first called with a`ReflectPermission("suppressAccessChecks")` permission.
A `SecurityException` is also thrown if this object is a`Constructor` object for the class `Class` and `flag` is true.
Overrides:
`[setAccessible](../../../java/lang/reflect/AccessibleObject.html#setAccessible%28boolean%29)` in class `[AccessibleObject](../../../java/lang/reflect/AccessibleObject.html "class in java.lang.reflect")`
Parameters:
`flag` \- the new value for the `accessible` flag
Throws:
`[InaccessibleObjectException](../../../java/lang/reflect/InaccessibleObjectException.html "class in java.lang.reflect")` \- if access cannot be enabled
`[SecurityException](../../../java/lang/SecurityException.html "class in java.lang")` \- if the request is denied by the security manager or this is a constructor for `java.lang.Class`
See Also:
[AccessibleObject.trySetAccessible()](../../../java/lang/reflect/AccessibleObject.html#trySetAccessible%28%29), [MethodHandles.privateLookupIn(java.lang.Class<?>, java.lang.invoke.MethodHandles.Lookup)](../../../java/lang/invoke/MethodHandles.html#privateLookupIn%28java.lang.Class,java.lang.invoke.MethodHandles.Lookup%29)
* #### getDeclaringClass
public [Class](../../../java/lang/Class.html "class in java.lang")<[T](../../../java/lang/reflect/Constructor.html "type parameter in Constructor")> getDeclaringClass()
Returns the `Class` object representing the class that declares the constructor represented by this object.
Specified by:
`[getDeclaringClass](../../../java/lang/reflect/Member.html#getDeclaringClass%28%29)` in interface `[Member](../../../java/lang/reflect/Member.html "interface in java.lang.reflect")`
Specified by:
`[getDeclaringClass](../../../java/lang/reflect/Executable.html#getDeclaringClass%28%29)` in class `[Executable](../../../java/lang/reflect/Executable.html "class in java.lang.reflect")`
Returns:
an object representing the declaring class of the underlying member
* #### getName
public [String](../../../java/lang/String.html "class in java.lang") getName()
Returns the name of this constructor, as a string. This is the binary name of the constructor's declaring class.
Specified by:
`[getName](../../../java/lang/reflect/Member.html#getName%28%29)` in interface `[Member](../../../java/lang/reflect/Member.html "interface in java.lang.reflect")`
Specified by:
`[getName](../../../java/lang/reflect/Executable.html#getName%28%29)` in class `[Executable](../../../java/lang/reflect/Executable.html "class in java.lang.reflect")`
Returns:
the simple name of the underlying member
* #### getTypeParameters
public [TypeVariable](../../../java/lang/reflect/TypeVariable.html "interface in java.lang.reflect")<[Constructor](../../../java/lang/reflect/Constructor.html "class in java.lang.reflect")<[T](../../../java/lang/reflect/Constructor.html "type parameter in Constructor")>>[] 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](../../../java/lang/reflect/GenericDeclaration.html#getTypeParameters%28%29)` in interface `[GenericDeclaration](../../../java/lang/reflect/GenericDeclaration.html "interface in java.lang.reflect")`
Specified by:
`[getTypeParameters](../../../java/lang/reflect/Executable.html#getTypeParameters%28%29)` in class `[Executable](../../../java/lang/reflect/Executable.html "class in java.lang.reflect")`
Returns:
an array of `TypeVariable` objects that represent the type variables declared by this generic declaration
Throws:
`[GenericSignatureFormatError](../../../java/lang/reflect/GenericSignatureFormatError.html "class in java.lang.reflect")` \- if the generic signature of this generic declaration does not conform to the format specified inThe Java™ Virtual Machine Specification
Since:
1.5
* #### getParameterCount
public int getParameterCount()
Returns the number of formal parameters (whether explicitly declared or implicitly declared or neither) for the executable represented by this object.
Overrides:
`[getParameterCount](../../../java/lang/reflect/Executable.html#getParameterCount%28%29)` in class `[Executable](../../../java/lang/reflect/Executable.html "class in java.lang.reflect")`
Returns:
The number of formal parameters for the executable this object represents
Since:
1.8
* #### getGenericParameterTypes
public [Type](../../../java/lang/reflect/Type.html "interface in java.lang.reflect")[] getGenericParameterTypes()
Returns an array of `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.
Overrides:
`[getGenericParameterTypes](../../../java/lang/reflect/Executable.html#getGenericParameterTypes%28%29)` in class `[Executable](../../../java/lang/reflect/Executable.html "class in java.lang.reflect")`
Returns:
an array of `Type`s that represent the formal parameter types of the underlying executable, in declaration order
Throws:
`[GenericSignatureFormatError](../../../java/lang/reflect/GenericSignatureFormatError.html "class in java.lang.reflect")` \- if the generic method signature does not conform to the format specified inThe Java™ Virtual Machine Specification
`[TypeNotPresentException](../../../java/lang/TypeNotPresentException.html "class in java.lang")` \- if any of the parameter types of the underlying executable refers to a non-existent type declaration
`[MalformedParameterizedTypeException](../../../java/lang/reflect/MalformedParameterizedTypeException.html "class in java.lang.reflect")` \- if any of the underlying executable's parameter types refer to a parameterized type that cannot be instantiated for any reason
Since:
1.5
* #### getGenericExceptionTypes
public [Type](../../../java/lang/reflect/Type.html "interface in java.lang.reflect")[] getGenericExceptionTypes()
Returns an array of `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.
Overrides:
`[getGenericExceptionTypes](../../../java/lang/reflect/Executable.html#getGenericExceptionTypes%28%29)` in class `[Executable](../../../java/lang/reflect/Executable.html "class in java.lang.reflect")`
Returns:
an array of Types that represent the exception types thrown by the underlying executable
Throws:
`[GenericSignatureFormatError](../../../java/lang/reflect/GenericSignatureFormatError.html "class in java.lang.reflect")` \- if the generic method signature does not conform to the format specified inThe Java™ Virtual Machine Specification
`[TypeNotPresentException](../../../java/lang/TypeNotPresentException.html "class in java.lang")` \- if the underlying executable's`throws` clause refers to a non-existent type declaration
`[MalformedParameterizedTypeException](../../../java/lang/reflect/MalformedParameterizedTypeException.html "class in java.lang.reflect")` \- if the underlying executable's `throws` clause refers to a parameterized type that cannot be instantiated for any reason
Since:
1.5
* #### equals
public boolean equals([Object](../../../java/lang/Object.html "class in java.lang") 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](../../../java/lang/Object.html#equals%28java.lang.Object%29)` in class `[Object](../../../java/lang/Object.html "class in java.lang")`
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()](../../../java/lang/Object.html#hashCode%28%29), [HashMap](../../../java/util/HashMap.html "class in java.util")
* #### 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](../../../java/lang/Object.html#hashCode%28%29)` in class `[Object](../../../java/lang/Object.html "class in java.lang")`
Returns:
a hash code value for this object.
See Also:
[Object.equals(java.lang.Object)](../../../java/lang/Object.html#equals%28java.lang.Object%29), [System.identityHashCode(java.lang.Object)](../../../java/lang/System.html#identityHashCode%28java.lang.Object%29)
* #### toString
public [String](../../../java/lang/String.html "class in java.lang") 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)
```
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.
Overrides:
`[toString](../../../java/lang/Object.html#toString%28%29)` in class `[Object](../../../java/lang/Object.html "class in java.lang")`
Returns:
a string describing this `Constructor`
See The Java™ Language Specification:
8.8.3 Constructor Modifiers, 8.9.2 Enum Body Declarations
* #### toGenericString
public [String](../../../java/lang/String.html "class in java.lang") 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 class name. 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 generic 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.
Specified by:
`[toGenericString](../../../java/lang/reflect/Executable.html#toGenericString%28%29)` in class `[Executable](../../../java/lang/reflect/Executable.html "class in java.lang.reflect")`
Returns:
a string describing this `Constructor`, include type parameters
Since:
1.5
See The Java™ Language Specification:
8.8.3 Constructor Modifiers, 8.9.2 Enum Body Declarations
* #### newInstance
public [T](../../../java/lang/reflect/Constructor.html "type parameter in Constructor") newInstance([Object](../../../java/lang/Object.html "class in java.lang")... initargs)
throws [InstantiationException](../../../java/lang/InstantiationException.html "class in java.lang"),
[IllegalAccessException](../../../java/lang/IllegalAccessException.html "class in java.lang"),
[IllegalArgumentException](../../../java/lang/IllegalArgumentException.html "class in java.lang"),
[InvocationTargetException](../../../java/lang/reflect/InvocationTargetException.html "class in java.lang.reflect")
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 ofThe 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:
`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](../../../java/lang/Float.html "class in java.lang"))
Returns:
a new object created by calling the constructor this object represents
Throws:
`[IllegalAccessException](../../../java/lang/IllegalAccessException.html "class in java.lang")` \- if this `Constructor` object is enforcing Java language access control and the underlying constructor is inaccessible.
`[IllegalArgumentException](../../../java/lang/IllegalArgumentException.html "class in java.lang")` \- 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](../../../java/lang/InstantiationException.html "class in java.lang")` \- if the class that declares the underlying constructor represents an abstract class.
`[InvocationTargetException](../../../java/lang/reflect/InvocationTargetException.html "class in java.lang.reflect")` \- if the underlying constructor throws an exception.
`[ExceptionInInitializerError](../../../java/lang/ExceptionInInitializerError.html "class in java.lang")` \- if the initialization provoked by this method fails.
* #### isVarArgs
public boolean isVarArgs()
Returns `true` if this executable was declared to take a variable number of arguments; returns `false` otherwise.
Overrides:
`[isVarArgs](../../../java/lang/reflect/Executable.html#isVarArgs%28%29)` in class `[Executable](../../../java/lang/reflect/Executable.html "class in java.lang.reflect")`
Returns:
`true` if an only if this executable was declared to take a variable number of arguments.
Since:
1.5
* #### isSynthetic
public boolean isSynthetic()
Returns `true` if this executable is a synthetic construct; returns `false` otherwise.
Specified by:
`[isSynthetic](../../../java/lang/reflect/Member.html#isSynthetic%28%29)` in interface `[Member](../../../java/lang/reflect/Member.html "interface in java.lang.reflect")`
Overrides:
`[isSynthetic](../../../java/lang/reflect/Executable.html#isSynthetic%28%29)` in class `[Executable](../../../java/lang/reflect/Executable.html "class in java.lang.reflect")`
Returns:
true if and only if this executable is a synthetic construct as defined byThe Java™ Language Specification.
Since:
1.5
See The Java™ Language Specification:
13.1 The Form of a Binary
* #### getAnnotation
public <T extends [Annotation](../../../java/lang/annotation/Annotation.html "interface in java.lang.annotation")> T getAnnotation([Class](../../../java/lang/Class.html "class in java.lang")<T> annotationClass)
Returns this element's annotation for the specified type if such an annotation is _present_, else null.
Specified by:
`[getAnnotation](../../../java/lang/reflect/AnnotatedElement.html#getAnnotation%28java.lang.Class%29)` in interface `[AnnotatedElement](../../../java/lang/reflect/AnnotatedElement.html "interface in java.lang.reflect")`
Overrides:
`[getAnnotation](../../../java/lang/reflect/Executable.html#getAnnotation%28java.lang.Class%29)` in class `[Executable](../../../java/lang/reflect/Executable.html "class in java.lang.reflect")`
Type Parameters:
`T` \- the type of the annotation to query for and return if present
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](../../../java/lang/NullPointerException.html "class in java.lang")` \- if the given annotation class is null
Since:
1.5
* #### getDeclaredAnnotations
public [Annotation](../../../java/lang/annotation/Annotation.html "interface in java.lang.annotation")[] getDeclaredAnnotations()
Returns annotations that are _directly present_ on this element. This method ignores inherited annotations. If there are no annotations _directly present_ on this element, the return value is an array of length 0\. 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](../../../java/lang/reflect/AnnotatedElement.html#getDeclaredAnnotations%28%29)` in interface `[AnnotatedElement](../../../java/lang/reflect/AnnotatedElement.html "interface in java.lang.reflect")`
Overrides:
`[getDeclaredAnnotations](../../../java/lang/reflect/AccessibleObject.html#getDeclaredAnnotations%28%29)` in class `[AccessibleObject](../../../java/lang/reflect/AccessibleObject.html "class in java.lang.reflect")`
Returns:
annotations directly present on this element
Since:
1.5
* #### getParameterAnnotations
public [Annotation](../../../java/lang/annotation/Annotation.html "interface in java.lang.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. 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](../../../java/lang/reflect/Parameter.html "class in java.lang.reflect") for more information.
Specified by:
`[getParameterAnnotations](../../../java/lang/reflect/Executable.html#getParameterAnnotations%28%29)` in class `[Executable](../../../java/lang/reflect/Executable.html "class in java.lang.reflect")`
Returns:
an array of arrays that represent the annotations on the formal and implicit parameters, in declaration order, of the executable represented by this object
Since:
1.5
See Also:
[Parameter](../../../java/lang/reflect/Parameter.html "class in java.lang.reflect"), [AnnotatedElement.getAnnotations()](../../../java/lang/reflect/AnnotatedElement.html#getAnnotations%28%29)
* #### getAnnotatedReturnType
public [AnnotatedType](../../../java/lang/reflect/AnnotatedType.html "interface in java.lang.reflect") 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. 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.
Specified by:
`[getAnnotatedReturnType](../../../java/lang/reflect/Executable.html#getAnnotatedReturnType%28%29)` in class `[Executable](../../../java/lang/reflect/Executable.html "class in java.lang.reflect")`
Returns:
an object representing the return type of the method or constructor represented by this `Executable`
Since:
1.8
* #### getAnnotatedReceiverType
public [AnnotatedType](../../../java/lang/reflect/AnnotatedType.html "interface in java.lang.reflect") 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. 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 an instance method or represents a constructor of an inner member class_, and the method/constructor _either_ has no 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 or represents a constructor of a top level, static member, local, or anonymous class, then the return value is null.
Overrides:
`[getAnnotatedReceiverType](../../../java/lang/reflect/Executable.html#getAnnotatedReceiverType%28%29)` in class `[Executable](../../../java/lang/reflect/Executable.html "class in java.lang.reflect")`
Returns:
an object representing the receiver type of the method or constructor represented by this `Executable` or `null` if this `Executable` can not have a receiver parameter
Since:
1.8