java.lang.reflect
class Constructor

java.lang.Object java.lang.reflect.AccessibleObject java.lang.reflect.Constructor

All Implemented Interfaces:

AnnotatedElement, GenericDeclaration, Member

public final class Constructor
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.

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

getAnnotation

public Annotation getAnnotation(Class annotationClass)

Overrides:

getAnnotation in class AccessibleObject

Parameters:

annotationClass

getDeclaredAnnotations

public Annotation[] getDeclaredAnnotations()

Overrides:

getDeclaredAnnotations in class AccessibleObject

getDeclaringClass

public Class getDeclaringClass()

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

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

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

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.

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.

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

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

getTypeParameters

public 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. Returns an array of length 0 if the underlying generic declaration declares no type variables.

Returns:

an array of TypeVariable objects that represent the type variables declared by this generic declaration

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

isSynthetic

public boolean isSynthetic()

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

Returns:

true if and only if this constructor is a synthetic constructor as defined by the Java Language Specification.

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.

newInstance

public Object 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 {@link java.lang.Float Float})

Returns:

a new object created by calling the constructor this object represents

Throws:

InstantiationException - if the class that declares the underlying constructor represents an abstract class.

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.

InvocationTargetException - if the underlying constructor throws an exception.

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

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