java.lang.reflect
Class Constructorjava.lang.Object | +--java.lang.reflect.AccessibleObject | +--java.lang.reflect.Constructor
- All Implemented Interfaces:
- Member
- public final class Constructor
- extends AccessibleObject
- implements 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()
Field Summary
Fields inherited from interface java.lang.reflect.Member DECLARED, PUBLIC
Method Summary
boolean equals(Object obj)
Compares this Constructor against the specified object.Class 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 of exceptions declared to be thrown by the underlying constructor 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.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.int hashCode()
Returns a hashcode for this Constructor.Object 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 toString()
Returns a string describing this Constructor.
Methods inherited from class java.lang.reflect.AccessibleObject isAccessible, setAccessible, setAccessible
Methods inherited from class java.lang.Object clone, finalize, getClass, notify, notifyAll, wait, wait, wait
Method Detail
getDeclaringClass
public Class 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
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
getExceptionTypes
public Class[] getExceptionTypes()
- Returns an array of Class objects that represent the types of 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
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.
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 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.
- 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.