Overriding default constructor

I'm on Oracle 10gR2. I need to know how to override the default constructor for a user defined object. The docs say that this is possible. But it wont allow me to add a constructor with the same params as the default constructor. Does anyone know how?
CREATE OR REPLACE TYPE period AS OBJECT (
start_time DATE,
end_time DATE,
-- This fails
CONSTRUCTOR FUNCTION period(p_start DATE, p_end DATE)
RETURN SELF AS RESULT
...

Betsy
(a) You are getting the correct port, so your super(port) must be calling UnicastRemoteObject.UnicastRemoteObject(port). Yes? This is what the Java Language Spec says it should do and if it did anything else oceans of JDK code would break. The only inference possible is that this is not happening.
(b) You're also getting another listening port. I think this is the RMI DGC server being initiated by the export of this object. (Does your object have a socket factory?) Export a few more objects and see if you get 2N listening ports or N+1.
I'm also confused by you saying that all this happens at the client when the remote server is down. Is this a callback object?
Can you show us the constructor of your remote object?

Similar Messages

Overriding default constructor in extended class

I've got some code that extends UnicastRemoteObject. The UnicastRemoteObject's default constructor open a random tcp/ip port. I'd like to control what port is opened. The UnicastRemoteObject has another constructor which takes a port as input. I'd like to override the default constructor. I've read that if I specify a call to super(<int>) that the default constructor wouldn't be called but the constructor taking an int would be called. I tried this but got both the default constructor (random tcp/ip port opened) and the constructor I called (shown by the port I specified being opened). Am I doing something wrong? Is there another way to control the constructor initiated in the class that is extended ?

I'd like to
override the default constructor.Yes but why?
I've read that if I
specify a call to super(<int>) that the default
constructor wouldn't be called but the constructor
taking an int would be called.Correct.
I tried this but got
both the default constructor (random tcp/ip port
opened) and the constructor I called (shown by the
port I specified being opened).I doubt this very much. You need to review your evidence for this assertion. You should call super(port) if you have a specific port in mind, and in JDK 1.5 you should call it anyway with 0 if you don't want to have to generate stubs.
This question would be better off in the RMI forum.
EJP

Overriding default constructor in extended UnicastRemoteObject

I've got some code that extends UnicastRemoteObject. The UnicastRemoteObject's default constructor open a random tcp/ip port. I'd like to control what port is opened. The UnicastRemoteObject has another constructor which takes a port as input. I'd like to override the default constructor. I've read that if I specify a call to super(<int>) that the default constructor wouldn't be called but the constructor taking an int would be called. I tried this but got both the default constructor (random tcp/ip port opened) and the constructor I called (shown by the port I specified being opened). Am I doing something wrong? Is there another way to control the constructor initiated in the class that is extended ?

Betsy
(a) You are getting the correct port, so your super(port) must be calling UnicastRemoteObject.UnicastRemoteObject(port). Yes? This is what the Java Language Spec says it should do and if it did anything else oceans of JDK code would break. The only inference possible is that this is not happening.
(b) You're also getting another listening port. I think this is the RMI DGC server being initiated by the export of this object. (Does your object have a socket factory?) Export a few more objects and see if you get 2N listening ports or N+1.
I'm also confused by you saying that all this happens at the client when the remote server is down. Is this a callback object?
Can you show us the constructor of your remote object?

Failing with 'no-arg default constructor' on @XmlTransient

Hello,
I have a simple exception I want to serialize to xml like this:
public class Main {
@XmlRootElement
static public class SomeException extends RuntimeException {
private Integer someAdditionalInformation;
public SomeException() {
public SomeException(Integer someAdditionalInformation) {
this.someAdditionalInformation = someAdditionalInformation;
public Integer getSomeAdditionalInformation() {
return someAdditionalInformation;
public void setSomeAdditionalInformation(
Integer someAdditionalInformation) {
this.someAdditionalInformation = someAdditionalInformation;
@XmlTransient
@Override
public StackTraceElement[] getStackTrace() {
return super.getStackTrace();
public static void main(String[] args) {
try {
JAXBContext jaxbCtx = JAXBContext.newInstance(SomeException.class);
Marshaller m = jaxbCtx.createMarshaller();
m.marshal(new SomeException(5), System.out);
} catch (JAXBException ex) {
Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
But I get the following exception:
com.sun.xml.internal.bind.v2.runtime.IllegalAnnotationsException: 1 counts of IllegalAnnotationExceptions
java.lang.StackTraceElement does not have a no-arg default constructor.
this problem is related to the following location:
at java.lang.StackTraceElement
at public java.lang.StackTraceElement[] java.lang.Throwable.getStackTrace()
at java.lang.Throwable
at java.lang.Exception
at java.lang.RuntimeException
at jaxbtest.Main$SomeException
Does this seam like a JAXB bug ?
@XmlTransient should make JAXB just skip that property.
Is there ant way to workaround this ?
PS. Where did the JAXB team fly away ? jaxb.dev.java.net is blank

Looking at your log it is clear that, you are populating Xellerate Type=null. This is mandatory field and can't be null. However, when you create user using UI, the default value "End-Users" is being passed by default, because we have the corresponding field "Design Console" access check box at oim user profile.
Just map the constant value for trusted recon
Xellerate Type=End-Users
--nayan

Require default constructor

Although I doubt there is, I would like to know if there is a way to require subclasses to implement the default constructor. I am retrieving String class names from a data file and creating objects with the combination of Class.forName(...) and newInstance() (also from Class class). I just wanted to create them without having to deal with various combinations of constructors.

CharanZ wrote:
Java Creates a default constructor for every class you create, Unless you override it.Except that a) C'tors are not inherited and thus cannot be overridden, and b) If you explicitly define any c'tor, then the compiler no longer provides the default.
So no need to worry about it.Except that there's no way to do what the OP asks, except, as already pointed out, by documentation and trusting the subclass author to follow it.

De-serialization not calling default constructor ??

Hi,
I have a strange problem with serialization (de-serialization, actually):
I have a bunch of classes that represent the model for my application.
These classes are organized as a complex tree and come in three flavors:
public abstract class AbstractIOCLeaf implements IOCElement {
     private String name;
     private transient boolean changed = false;
     private transient LinkedList<ChangeListener> changeListeners;
     protected AbstractIOCLeaf() {
          super();
          name = null;
          changed = false;
          changeListeners = new LinkedList<ChangeListener>();
     } //needed for Serialzation
     protected AbstractIOCLeaf(String name) {
          this();
          this.name = name;
...this class is a leaf: it cannot contain other sub-elements.
public abstract class AbstractIOCList<T extends IOCElement> extends AbstractIOCNode implements ComboBoxModel {
     protected LinkedList<T> list = null;
     protected transient List<ListDataListener> listListeners;
     protected abstract T newElement(String name);
     protected AbstractIOCList() { super(); listListeners = new LinkedList<ListDataListener>(); }
     public AbstractIOCList(String name) {
          super(name);
          list = new LinkedList<T>();
          listListeners = new LinkedList<ListDataListener>();
... This class holds a list of elements that are all equal.
and finally:
public abstract class AbstractIOCNode extends AbstractIOCLeaf implements ChangeListener, ListDataListener {
     protected AbstractIOCNode() { super(); }
     protected AbstractIOCNode(String name) {
          super(name);
... This class holds elements that are all different.
The actual classes extends one of these following the pattern:
public class StateMachine extends AbstractIOCNode {
     private StateList states = null;;
     private EventQueue fEventQueue = null;
     private StateMachine() { super(); }
     private StateMachine(String name) {
          super(name);
          states = StateList.newInstance(this);
          changed = false;
     public static StateMachine newInstance(String name) {
          StateMachine sm = new StateMachine(name);
          sm.initialize();
          return sm;
public class StateList extends AbstractIOCList<State> {
     private StateMachine sm;
     private StateList() { super("StateList"); sm = null; }
     private StateList(StateMachine sm) {
          this();
          this.sm = sm;
     public static StateList newInstance(StateMachine sm) {
          StateList list = new StateList(sm);
          list.initialize();
          return list;
...etc. etc.
I do serialization calling ObjectOutputStream.writeObject on the root object and (obviously) deserialize using ObjectOutputStream.readObject.
The process works, but it seems that the default constructors in particular AbstractIOCLeaf() is never called while deserializing. First hint to something amiss was the fact that I always had the transient field changeListeners remaining in its default null state.
Further investigation involving debugging and breakpointing confirmed no default constructor is called in spite of the super(); calls.
What am I doing wrong??
Did I miss something about serialization (apparently so, but I cannot understand what!)?
Side issue:
I tried substituting ObjectOutputStream.writeObject with XMLEncoder.writeObject, but then I get the error: "Class sun.reflect.misc.Trampoline can not access a member of class com.softin.IOCbuilder.model.IOController with modifiers "private"".
Aren't those classes supposed to be equivalent?
Is there any (fast) way to desume the offending member?
Excuse me for the length of the post and
Thanks in Advance
Mauro

Oops, nevermind. Sorry.

Creating an instance of a class with no default constructor

Hello gurus,
I wrote my own serialization and RMI protocol for both C++ and Java that follows closely what the default Java version does. I'm trying to recreate an object on the Java side that was sent over the wire. The first step is to create an instance of the class. How do I create an instance of a class that has no constructor (i.e. the only instances are static, created by the class itself and returned by static methods) or one that has no default constructor (like Integer)? The Java serialization seems to support it but the reflection API doesn't seem to have any support for this (i.e. Class::newInstance() and Constructor::newInstance()). It seems that through the standard API you can only create an object via one of its constructors. There must be a "hidden" method somewhere that allows the Java serialization to create an object without calling a constructor - where is it?
Dominique

There must be a "hidden" method
somewhere that allows the Java serialization to create
an object without calling a constructor - where is
it?You are correct, the way in which the Serialization creates Objects is "hidden" deep within the runtime.
If it were not hidden, you would be able to find it, and use it to violate the integrity of the VM.

ORA-02315: incorrect number of arguments for default constructor

I was able to register the XML schema successfully by letting Oracle creating the XML Types. Then when I try to execute the create view command the ORA-02315: incorrect number of arguments for default constructor is always raised.
I tried using the XMLTYPE.createXML but it gives me the same error.
Command:
CREATE OR REPLACE VIEW samples_xml OF XMLTYPE
XMLSCHEMA "http://localhost/samplepeak4.xsd" ELEMENT "SAMPLE"
WITH OBJECT ID (ExtractValue(sys_nc_rowinfo$, '/SAMPLES/SAMPLE/SAMPLE_ID')) AS
SELECT sample_t(s.sample_id, s.patient_info, s.process_info, s.lims_sample_id,
cast (multiset(
SELECT peak_t(p.peak_id, p.mass_charge, p.intensity, p.retention_time,
p.cleavage_type, p.search_id, p.match_id, p.mass_observed,
p.mass_expected, p.delta, p.miss, p.rank, p.mass_calculated,
p.fraction)
FROM peak p
WHERE s.sample_id = p.sample_id) AS PEAK107_COLL))
FROM sample s;
Can someone help me.
Thanks
Carl

This example runs without any problems on 9.2.0.4.0. Which version are you running? And which statement causes the error message?

Selective member import/export using dllexport and default constructor

We can only export some methods in the class(https://msdn.microsoft.com/es-es/library/8d7d1303-b9e9-47ca-96cc-67bf444a08a9%28v=vs.100%29)
What if we export only some methods in the class and not exported the default constructor(Will it get generated by the compiler in external app which use this dll?).The class may have some private data member as well which are not exposed in the published
header file(Which we distribute with DLL).
How the memory gets allocated to those private data members which are not exposed as the default constructor is not exported?
Niranjan

We can only export some methods in the class(https://msdn.microsoft.com/es-es/library/8d7d1303-b9e9-47ca-96cc-67bf444a08a9%28v=vs.100%29)
What if we export only some methods in the class and not exported the default constructor(Will it get generated by the compiler in external app which use this dll?).The class may have some private data member as well which are not exposed in the published
header file(Which we distribute with DLL).
How the memory gets allocated to those private data members which are not exposed as the default constructor is not exported?
Niranjan

No appropriate default constructor c++

Hi, have been trying to read up on it but I need some help to understand it, here's my code. What should I do to make it work and how should I try to think about it in the future?
cheers
Law.h
#include <iostream>
#include <string>
using namespace std;
class Law
private:
int k;
int x;
int F;
int m;
const int g;
void init();
public:
void Introduce();
int getMass();
int getLenght();
Law.ccp
#include "Law.h"
int Law::getMass()
return m;
int Law::getLenght()
return x;
void Law::Introduce()
cout << "\nWelcome to a very simplified Hooke's Law Calculator" << endl;
cout << "\nplease type in your mass: ";
main.ccp
#include <iostream>
#include <string>
#include "Law.h"
using namespace std;
int main()
Law hLaw;
hLaw.Introduce();
system("pause");
return 0;

On 1/11/2015 8:50 AM, RonnerBBQ wrote:
class Law
private:
const int g;
Law hLaw;
The variable hLaw needs to be initialized - with a default constructor in this case. Class Law doesn't have any user-defined constructors. Normally, a compiler would implicitly define a default constructor, equivalent to Law::Law() {} . But in
this case, it can't - Law has a const data member, which must be initialized in constructor (it being const, there won't be any other chance), and the compiler doesn't know what value to initialize it to.
You can 1) explicitly define a default constructor, and initialize g there, or 2) drop "const" from g (or drop g entirely, seeing as you aren't using it), or 3) give g an initializer, as in "const int g = 42;"
Igor Tandetnik

Problem overriding default JSF conversion error messages

Hello !
I have a problem to override default JSF conversation error message. I have an inputText which is binded to BigDecimal attribute, so when I enter a character in that field I get this error message: "- Conversion failed."
I think I need to register the message bundle in my faces config, and put the key of this error message to my properties file.. am I right ?
Can somebody help me with this ? Which key I need to put into the properties file ?
Miljan

Get [Sun's Java EE tutorial |https://www.sun.com/offers/details/JavaEETutorial.xml?cid=20090723ZA_TACO_JVEE_0004] and read the relevant section so you don't have to guess what you need to do.

Super class default constructor

Hello,
I want to clear some confusion. I am studying for the exam. In this particular book an example shows that
Super class has 2 constructor
public abc() and public abc(int n)
Sub class has 2 constructor
public xyz() and public xyz(int n)
now when an instance is created for the subclass
xyz t = new xyz(1)
It will invoke the super class no argument constructor eventhough a default constructor exist in subclass?
Regards,
adil

Here are the rules for constructors--"ctors" because I'm lazy. Also, because I'm lazy, "super(...)" and "this(...)" mean any super or this call, regardless of how many args it takes, including those that take no args.
1) Every class has at least one ctor.
1.1) If you do not define an explicit constructor for your class, the compiler provides a implicit constructor that takes no args and simply calls super().
1.2) If you do define one or more explicit constructors, regardless of whether they take args, then the compiler no longer provides the implicit no-arg ctor. In this case, you must explicitly define a public MyClass() {...} if you want one.
1.3) Constructors are not inherited.
2) The first statement in the body of any ctor is either a call to a superclass ctor super(...) or a call to another ctor of this class this(...) 2.1) If you do not explicitly put a call to super(...) or this(...) as the first statement in a ctor that you define, then the compiler implicitly inserts a call to super's no-arg ctor super() as the first call. The implicitly called ctor is always super's no-arg ctor, regardless of whether the currently running ctor takes args.
2.2) There is always exactly one call to either super(...) or this(...) in each constructor, and it is always the first call. You can't put in more than one, and if you put one in, the compiler's implicitly provided one is removed.

What is the need for calling default constructor by JVM?

What is the need for calling default constructor by JVM? why the JVM should intiializes default values to the data
fields if the constructor is not there in our class?

mahar wrote:
What is the need for calling default constructor by JVM? Huh? The JVM does not need to call the default constructor. It needs to call a constructor.
You decide which one by the way you use "new".
why the JVM should initialize default values to the data fieldsHuh?
... if the constructor is not there in our class?Huh? The default constructor is always there. It may be private but it is still there.

Will 1.5 compiler tag default constructor as synthetic?

Hi,
This is a question about the synthetic attribute for the default constructor. This attribute has been added at the moment the inner classes have been introduced in the language. I think its purpose is to distinguish methods added by the compiler (like the access methods) to handle the inner classes.
Synthetic basically means something that has been added by the compiler and that has no corresponding source code.
Following this, the default constructor (added when the class has no constructor) should also be tagged with a synthetic attribute, shouldn't it?
Javac 1.4.2 doesn't add this attribute for the default constructor and I was wondering if the version 1.5 would do it.
Thanks,
Olivier

As far as I tested the jdk 1.5 compiler, I found that
it already tags default constructors with isSynthetic
attribute. Default constructors are compiler generated
and I am not sure how it affects the api, if they are
tagged isSynthetic.No, the 1.50 beta 31 compiler does not tag default constructors with Synthetic attributes.

Create POJO instance in fxml with no default constructor

My question is that how to create POJO instance in fxml that has no default constructor. I am creating pie chart data object in fxml like this
*<fx:define>*
*<PieChart.Data fx:id="data" >*
*<name>java</name>*
*<pieValue>20.2</pieValue>*
*</PieChart.Data>*
*</fx:define>*
since there is no default constructor how to create this object fxml?
Edited by: 988476 on Feb 16, 2013 6:21 AM

There must be a "hidden" method
somewhere that allows the Java serialization to create
an object without calling a constructor - where is
it?You are correct, the way in which the Serialization creates Objects is "hidden" deep within the runtime.
If it were not hidden, you would be able to find it, and use it to violate the integrity of the VM.

Overriding default constructor

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