Base classes with Collection attributes

I have a question. Suppose I have a base class A, an abstract base class
to be exact, and subclasses B and C. Assume A has an attribute of
Collection type, let's call it collectionImpl. Now I would like subclasses
B and C to be able to have elements of different types along the lines of
what I've outlined below.
Strictly speaking, class A wouldn't have to be PC, since I primarily care
of B and C but I wanted to show the structure.
<class name="A" persistence-capable-superclass="A">
<field name="collectionImpl">
<collection element type="someType"/>
</field>
</class>
<class name="B" persistence-capable-superclass="A">
<field name="collectionImpl">
<collection element type="someOtherType"/>
</field>
</class>
So, how would one express this?
Scott

Understood. Now for bit more clarification. Given my earlier example, what
if classes A, B and C implement the java.util.Collection interface. Does
Kodo have in issue with that? I know Kodo has this ProxyCollection stuff
but I don't really want to do that, nor do I think I really need to given
what I'm trying to accomplish.
The issue I'm having now is that the Kodo Enhancer is complaining that no
element-type is declared when I have an attribute of class type B for
example (implementing java.util.Collection) even though an element type is
declared for the that actual Collection object held in the base class of B
(A).
<class name="A" requires-extent="false">
<field name="impl">
<collection element-type="SomeType"/>
<extension vendor-name="kodo" key="ordered" value="true"/>
</field>
</class>
<class name="B" persistence-capable-superclass="A"
requires-extent="false"/>
Class "A" extends java.util.AbstractSet, impl is an instance of
java.util.Collection.
All this was working quite well until I made some updates recently
although the basic implementation is the same. Logically I don't know what
I might have done to cause the new error message.
I'm using v2.5.2 BTW.
Scott
Stephen Kim wrote:
The one thing to note is that if you do not make A persistent capable,
you cannot persist fields -declared- in A or query starting from A.
Scott A. Leschke wrote:
Can I acheive the same effect by making A be non-PC and provide a abstract
protected method that will be used by a to access the collection
implemented in the sub-classes as you suggest (ie. Collection
getCollectionImpl())?
Steve Kim
[email protected]
SolarMetric Inc.
http://www.solarmetric.com

Similar Messages

Using base classes for common attributes

Can TopLink handle use of non-mapped abstract base classes? There are a number of fields that are common to each and every one of my domain objects which, following good OO design principals, are moved up to a common superclass. So I have:
public abstract class AbstractDomainObject
private Integer id;
private Date dateCreated;
private Integer creatorId;
private Date dateModified;
private Integer modifierId;
// ... appropriate attribute accessors
Then a concrete class which gets mappped in Workbench:
public class Address
extends AbstractDomainObject
... specific attributes
I tried mapping all the specific attributes explicitly defined in the Address class and then using "Map Inherited Fields > To SuperClass" in Workbench. However, when attempting to test my mappings in the SessionConsole, only the attributes explicitly defined on Address are present in the SELECT clause.
Can what I am trying be done? If so, how?

Steve,
What you are trying to do is very common and the process you described is exactly how map the class. I will summarize a couple of points for mapping this scenario.
1. You only need to import Address in and map it. If AbstractDomainObject is imported into the Mapping Workbench make sure that it is disabled. The abstract class is only required on the project's CLASSPATH.
2. You should not enable inheritance for the Address class. Inheritance is for situations where the abstract base class has its own independent table. I am assuming that your Address class has its own table that contains fields for all of the attributes it needs along with those of the abstract base class.
Assuming these conditions are met then TopLink will work fine with you Address class just as if it had all of the inherited attributes directly.
If you are still having trouble take a look through your generated project (XML or Java) to ensure that mappings exist in Address for All attributes. If the project looks good then I am at a loss. Customers have been using this pattern of use for over 5 years with TopLink and Java inheritance.
Cheers,
Doug

Automatic Generation of classes with required attribute names

Hi ,
I am new to XML technologies ...I am having a problem in deciding whether I
should use JAXB or Castor for data binding.
The problem is the attributes I am to use are named differently as that found in
the DTD.I have creted my own classes using the required attribute names and the
n mapped them using the Castor mapping with the attributes.
I was wondering how should I achieve --"automatic generation of classes" with th
e specified attribute names?
I understand that JAXB can be used to automatically generate classes ,but this
uses the same default names as that of the XML file ..is there a way of forcing
JAXB to generate classes that use my name attributes rather than that of the XM
L dtd
If I use Castor ..is there a way to do the same.Generate Classes with the specif
id attributes

Hi ,
I am new to XML technologies ...I am having a problem in deciding whether I
should use JAXB or Castor for data binding.
The problem is the attributes I am to use are named differently as that found in
the DTD.I have creted my own classes using the required attribute names and the
n mapped them using the Castor mapping with the attributes.
I was wondering how should I achieve --"automatic generation of classes" with th
e specified attribute names?
I understand that JAXB can be used to automatically generate classes ,but this
uses the same default names as that of the XML file ..is there a way of forcing
JAXB to generate classes that use my name attributes rather than that of the XM
L dtd
If I use Castor ..is there a way to do the same.Generate Classes with the specif
id attributes

Abstract Entity classes with Collections

I trying to figure out a way to have a generics collection in a parent collection that can hold various entity types of the same super-class.
One thing I've tried was the following:
@Entity
public class ParentEnt implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
    @Column
    private String parentName;
    @OneToMany(mappedBy="parentEnt")
    private Collection<ChildAbs> children;
    /* Methods removed */
@Entity
public abstract class ChildAbs implements java.io.Serializable {
    protected static final long serialVersionUID = 1L;
    @Id
    protected Long id;
    @ManyToOne
    protected ParentEnt parentEnt;
    /* Methods removed */
@Entity
public class ChildEnt extends ChildAbs implements Serializable {
    @Column
    protected String childName;
}but this is the error I get:
Exception [TOPLINK-30005] (Oracle TopLink Essentials - 2.0 (Build b58g-fcs (09/07/2007))): oracle.toplink.essentials.exceptions.PersistenceUnitLoadingException
Exception Description: An exception was thrown while searching for persistence archives with ClassLoader: sun.misc.Launcher$AppClassLoader@11b86e7
Internal Exception: javax.persistence.PersistenceException: Exception [TOPLINK-28018] (Oracle TopLink Essentials - 2.0 (Build b58g-fcs (09/07/2007))): oracle.toplink.essentials.exceptions.EntityManagerSetupException
Exception Description: predeploy for PersistenceUnit [testPU] failed.
Internal Exception: Exception [TOPLINK-7250] (Oracle TopLink Essentials - 2.0 (Build b58g-fcs (09/07/2007))): oracle.toplink.essentials.exceptions.ValidationException
Exception Description: [class test.ParentEnt] uses a non-entity [class test.ChildAbs] as target entity in the relationship attribute [private java.util.Collection test.ParentEnt.children].So, it looks like there is no way to have a generics collection for an abstract entity class. Is there another way to accomplish what I want using a generics collection?
Additionally, entity ChildEnt generates an error due to the abstract class' id property not carrying forward (see Abstract Entities: http://java.sun.com/javaee/5/docs/tutorial/doc/bnbqa.html#bnbqo)
Exception Description: Entity class [class testprintservices.ChildEnt] has no primary key specified. It should define either an @Id, @EmbeddedId or an @IdClass.Any input would be appreciated.

As far as my first question, I was trying to make my collection so it can hold various type of entity classes, but now that I think about it, it was a bad idea. For instance, being able to hold ChildEnt and ChildEnt2 in the same collection. If JPA did allow this, it might be possible to save the entities to the DB, but the reverse wouldn't be possible.
Ok, regarding my 2nd question: I don't understand why having it as @Entity wouldn't. The links (mine and yours) clearly shows that @Id is carried forward in the example they provide. Anyway, since I can't use the superclass in the collection, this is pointless. I'll use the suggested annotation.
Thanks.

To access a method frm a class derived frm a base class with the same name

Here' s an example:-
class TestA {
public void start() {
System.out.println("TestA");
class TestB extends TestA {
public void start() {
System.out.println("TestB");
}In main method I do this:-
TestA testA = new TestA();
TestB testB = new TestB();
((TestA)testB).start();Output :-
TestB.
Now when i define the method as static :-
class TestA {
public static void start() {
System.out.println("TestA");
class TestB extends TestA {
public static void start() {
System.out.println("TestB");
}Then output is :-
TestA.
Can anyone let me know that when i say ((TestA)testB).start(); i.e i am type casting TestB obect to it base call then TestA should be printed but it doesn't print but when i declare method as static is does print TestA.
Thanks,
Heena

>
>
Secondly, when i say ((TestA).testB).start(); output is TestB. But when i define start() method as static output is TestA. I need clarity for the same.In the static case, all that the compiler is interested in is the class of the expression before the ".". Because you've put in an explicit cast the type of expression is assumed to be TestA the compiler doesn't know what kind of object will actually be referenced at runtime. In the static case which method is called is determined at compile time.
In the instance method case what determines the method called is determined the class of the actual, run time, value of the expression, and despite your cast, the actual value is still a reference to a TestB instance, so the TestB method is called. In the instance case which method called is determined at run time.

Problems using different tables for base class and derived class

I have a class named SuperProject and another class Project derived from
it. If I let SchemaTool generate the tables without specifying a "table"
extension, I get a single TABLE with all the columns from both classes and
everything works fine. But if I specify a "table" for the derived class,
SchemaTool generates the derived class with just one column (corresponds
to the attribute in derived class). Also it causes problems in using the
Project class in collection attributes.
JDO file:
<jdo>
<package name="jdo">
<class name="Project" identity-type="application"
persistence-capable-superclass="SuperProject">
<extension vendor-name="kodo" key="table" value="PROJECT"/>
</class>
<class name="SuperProject" identity-type="application"
objectid-class="ProjectId">
<field name="id" primary-key="true"/>
</class>
</package>
</jdo>
java classes:
public class Project extends SuperProject
String projectSpecific
public class SuperProject
BigDecimal id;
String name;
tables generated by SchemaTool:
TABLE SUPERPROJECTSX (IDX, JDOCLASSX, JDOLOCKX, NAMEX);
TABLE PROJECT(PROJECTSPECIFICX)
Thanks,
Justine Thomas

Justine,
This will be resolved in 2.3.4, to be released later this evening.
-Patrick
In article <aofo2q$mih$[email protected]>, Justine Thomas wrote:
I have a class named SuperProject and another class Project derived from
it. If I let SchemaTool generate the tables without specifying a "table"
extension, I get a single TABLE with all the columns from both classes and
everything works fine. But if I specify a "table" for the derived class,
SchemaTool generates the derived class with just one column (corresponds
to the attribute in derived class). Also it causes problems in using the
Project class in collection attributes.
JDO file:
<jdo>
<package name="jdo">
<class name="Project" identity-type="application"
persistence-capable-superclass="SuperProject">
<extension vendor-name="kodo" key="table" value="PROJECT"/>
</class>
<class name="SuperProject" identity-type="application"
objectid-class="ProjectId">
<field name="id" primary-key="true"/>
</class>
</package>
</jdo>
java classes:
public class Project extends SuperProject
String projectSpecific
public class SuperProject
BigDecimal id;
String name;
tables generated by SchemaTool:
TABLE SUPERPROJECTSX (IDX, JDOCLASSX, JDOLOCKX, NAMEX);
TABLE PROJECT(PROJECTSPECIFICX)
Thanks,
Justine Thomas
Patrick Linskey [email protected]
SolarMetric Inc. http://www.solarmetric.com

Class override, how to create the child class and then the base class

I started to write a program for a smart DMM, the problem is every version of the DMM the company change the communication commend.
My idea is to write a child class for every DMM version and every SubVI of the child will override the base class SubVI.
My problem is, i want first to create one child class and after i will see every thing is work, start to create the base class. that way i will see if am thinking the right way.
My question is
How can i create a child class and then create the base class and configure the SubVi of the child class to be Override of the base class?
I tried to search in the property of the class but i didn't see nothing.
Thanks
Solved!
Go to Solution.

This can be done and I've done it on occasion.
You simply create the base class with the dynamic dispatch methods you require (connector panes need to be identical to thos of the child class).
Then set the inheritance of the class to inherit from this base class. If your method is defined as a dynamic dispatch method in the parent, you'll most likely now have some errors (unless your child method was already DD in which case you might just be OK already).
To change the inheritance of a class, right-click the properties of the class in your project and select properties. I believe the ineritance tree is at the lower end of the properties. Click on the "change inheritance" (or something similar) to choose the class from which you now wish to inherit.
Say hello to my little friend.
RFC 2323 FHE-Compliant

Base Class NI View Fails

Hi
I am currently trying to leverage of my existing codebase by creating a Base class View containing common functionality. My goal is to create the Base class in the form of a (MFC) CFormView with an associated dialog resource containing all my NI controls and underlying code. From there I intend to derive further View Classes based on the former. I have tried this and cannot seem to get the Base class to recognise its members,i.e the Ni controls, whilst the view displays fine and I can see all the Ni controls on form derived from the Base class I cannot execute any of the base class meber functions that need a reference to the Ni controls. If you could give me an example of a project that derives it view from a Base class with ActiveX contro
ls in it I would be very appreciative.....
Regards

I was going to investigate it a little before posting, but
I'm not sure I can go any further on my own.
I am using the Yahoo Astra Flash Components. When I add a
Tree component, and give it a dataProvider that does not use any
nested nodes, it gives me the error. If I use even 1 nested node,
then it works correctly.
I am assuming that the error is stemming from the Yahoo
Component somewhere, just need to run down what is causing it.

Flash Pro is ignoring changes to my base class when publishing / debugging

Hi,
I hope this will be in the correct section of the forum.
I've been working with Actionscript 3 since a while now although most of the time I've just done straightforward coding using Flash Develop.
This is the first time I'm building a more or less complex project in Flash Pro.
Here's a quick outline of how the project is structured.
There is a swf file which holds a large set of components. Things like Buttons, Sliders, complex List components, etc.
All of them are written from scratch not using any existing components (reason being project requirements).
As someone with a heavy programming background I've done as little as possible in the timeline / frames, most of my code lives in classes which are attached to the components I've created in Flash Pro.
These classes handle all the functionality. These classes then usually inherit from a base class where some basic functionality lies that I need across all components.
The components outlined above are all marked for export and lateron imported into other swf files where they are used.
So far so good, all that works like a charm.
Now here's the actual problem.
Today I needed to make changes to the base class to change some fundamental behaviour across all components that inherit from said base class.
The change in itself was fairly simple.
However, every time I now try to debug or publish it will completely ignore any change I've made and use the previous version of my base class?
I can go as far as completely emptying my base class and every time I debug or publish it will do so using the base class from before. I can see at runtime that it is the previous version because of the behaviour of the inherited components.
That's what I don't get. Where does it take that version from? I tried clearing the publish cash, to no avail.
I can pace tracers, nothing. If I add code to the base class and make an error it will complain so when I try to debug or publish but once fixed, it won't use any of it. It's still behaving as if it's using a previous version.
What makes all this even weirder is that if I take that new code and place it into another class and inherit my components from this one, then the build will use that new verison with the new code. If I switch back to the old base class with exactly the same code inside it will ignore it again and once more behave as if its an older version of it.
I've been looking around the net but simply can't find what this could be caused by.
Now, sure, I could simply use a new class and inherit all my components from a different base class but that's rather unpractical.
What I would like to know is, why does Flash Pro ignore any changes to this class? Is this an issue with how I inherit my component classes from a base class? I kind of doubt it because it has been working like a charm before.
Could this be a Flash Pro issue?
This is also not the first time I've come across this problem. The previous time however, after much tinkering, it went away. Today, it didn't. I would really like to get to the bottom of this.
FYI: I'm running Flash Pro CC. I design my components in Flash Pro and do all my coding in Flash Develop.
Any help would be greatly appreciated.

Hmm, my classes live in a subfolder of where my fla files live. (This sub folder again is divided into further folders to organise the code)
I haven't actually setup any class paths. (default class path is set to .)
If I set the default class path to the folder where my code lives I get a ton of errors telling my that my package names don't reflect the location of my files.
edit: That was a mistake on my side. I've set the class path to where my code lives and made sure the package names still match up.
Unfortunately it still ignores my base class (which lives in a sub folder of the defined class path)

Can Shuttles be based non-base table ViewObjects with transient attributes

Hello,
Users have to select records from a data collection and a Shuttle looks most appropriate/nice for this purpose. We can introduce technical intersection tables in order to generate the Shuttles with JHeadstart 10g R3 if necessary, but there is no “functional” need to update any data in the database and therefore it would be practical if the ‘right’ side from a Shuttle can be based non-base table ViewObjects with transient attributes only. So, our interested is to know which records have been selected, i.e. moved to the right side from the Shuttle.
Hope that my question is clear enough.
Greetings,
Michael

Michael,
This cannot be generated out-of-the-box.
It is easiest to add the shuttle post-generation to your page, and then create a custom template to generate your custom shuttle into the page. I suggest you take a look at an example of a generated shuttle in a page, and the JHeadstart IntersectionShuttleBean class. You will see that the value property of <af:selectManyShuttle> points to the selectedKeys method in the JHeadstart Shuttle bean. In your case, you can create your own managed bean and bind the value property to your own method which will provide you access to the selected rows. The value property of the selectItem within the af:selectManyShuttle determines the property that is used to identify the selected row (which is the row key in case of Jhs-generated shuttles).
Steven Davelaar,
JHeadstart Team.

How to deserialize xml with structure of abitrary nested layers of base class?

let say i want to represent arithmetic expression using xml:
<?xml version="1.0" encoding="utf-8" ?>
<expr>
<add>
<num>10</num>
<num>20</num>
</add>
</expr>
and here is my classes to represent this:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace Test
public abstract class Evaluable
public abstract int Eval();
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Xml.Serialization;
namespace Test
[Serializable]
[XmlRoot("expr")]
public class Expr
[XmlElement]
public Evaluable Evaluable { get; set; }
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Xml.Serialization;
namespace Test
[Serializable]
[XmlRoot("add")]
[XmlType("add")]
public class Add : Evaluable
[XmlElement]
public List<Evaluable> Elems { get; set; }
public override int Eval()
return Elems.Select(e => e.Eval()).Sum();
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Xml.Serialization;
namespace Test
[Serializable]
[XmlRoot("num")]
[XmlType("num")]
public class Num : Evaluable
[XmlText]
public int Val { get; set; }
public override int Eval()
return Val;
but it doesn't work, and it's reasonable, since Serializer doesn't know any thing about the subclass. but how to make it work?
here is my deserialization code:
var serializer = new XmlSerializer(typeof(Expr), new[] { typeof(Add), typeof(Num) });
Expr expr = null;
using (var file = new StreamReader("expr.xml"))
expr = serializer.Deserialize(file) as Expr;

I think what you want is to set the XmlElement attribute on the container (Elems).
It can be done if the deserializer can be made aware of all the potential subclasses of the base class. It's ok to put multiple XmlElement attributes on the container to let the deserializer know about the various subclasses it can deserialize.
I don't think there's a way to tell the XmlSerializer externally about new types. I could be wrong. [If someone shows me how to do that, I'd sure appreciate it!] [WORKAROUND: A potential workaround
is to create a class that contains all the potential children including the class itself and serialize that. Seems a little like cheating.]
Here is a complete example:
[Serializable]
public class Foo
[XmlAttribute( "name" )]
public string name;
[XmlElement( "Foo", Type = typeof( Foo ) )]
[XmlElement( "Bar", Type = typeof( Bar ) )]
public List<Foo> children = new List<Foo>();
public void Dump( int level )
ShowProperties( level );
foreach( var f in children ) {
f.Dump( level + 1 );
protected virtual void ShowProperties( int level )
Console.WriteLine( "{0}{1}", new string(' ', level * 4 ), name );
[Serializable]
public class Bar : Foo
public string stuff;
protected override void ShowProperties( int level )
base.ShowProperties( level );
Console.WriteLine( "{0}{1}", new string(' ', level * 4 ), stuff );
class Program
static void Main( string[] args )
// <Foo name="A">
// <Bar name="B">
// <Foo name="D" />
// <stuff>B's Stuff</stuff>
// </Bar>
// <Bar name="C">
// <stuff>C's Stuff</stuff>
// </Bar>
// </Foo>
// A
// B
// B's Stuff
// D
// C
// C's Stuff
Foo a = new Foo() { name = "A" };
Bar b = new Bar() { name = "B", stuff="B's Stuff" };
Bar c = new Bar() { name = "C", stuff="C's Stuff" };
Foo d = new Foo() { name = "D" };
a.children.Add( b );
a.children.Add( c );
b.children.Add( d );
XmlSerializer xs = new XmlSerializer( typeof( Foo ) );
// There:
XmlSerializerNamespaces ns = new XmlSerializerNamespaces( new[] { XmlQualifiedName.Empty } );
StringBuilder sb = new StringBuilder();
using( XmlWriter xw = XmlWriter.Create( sb, new XmlWriterSettings() {
OmitXmlDeclaration = true,
Indent = true
xs.Serialize( xw, a, ns );
Console.WriteLine( sb.ToString() );
// And Back Again:
using( StringReader sr = new StringReader( sb.ToString() ) )
Foo root = (Foo)xs.Deserialize( sr );
root.Dump( 0 );

In OBIEE, retrieving base members along with their attributes is very slow

I can use Attributes in the prompts and not in the actual report columns, then the report retrieval is very fast. But as soon as I add the Base Member, Attribute1, Measures1, Measure2 etc, the retrieval is slow. All the measures are dynamically calculated. Adding the attribute to the prompt - works fine. How do I design a aggregation with the attributes, I have enabled the enable query tracking. Any suggestions.

I really recommend reading the DBAG section I linked in your other recent question: Re: ASO Cube with attributes very slow in retrieval
For various classes of attribute queries, aggregations are not / can not be used - unfortunately this is just how ASO works. Personally, I have had to make what would logically be an attribute into a real, stored dimension because of this limitation.

Error with instance variable and constructor of base class

I am getting the error on the following statement "protected Point apoint" of by base class. What is causing this problem? See my code:
package Shapes;
public abstract class Shapes
     protected Point apoint; / ****error at this line****/
     public void move(double xdelta, double ydelta)
          apoint.x += xdelta;
          apoint.y += ydelta;
public abstract void distance();
public abstract void show();
public String toString()
return "\nThe starting point is at coordinates ("+x+","+y+")";
package Shapes;
public class Lines extends Shapes
protected Point start;
protected Point end;
     protected double x;
     protected double y;
     double delta;
     public Lines( final Point apoint, final Point bpoint)
start.x = apoint.x;
          start.y = apoint.y;
          end.x = bpoint.x;
          end.y = bpoint.y;
public Lines(double xstart, double ystart, double xend, double yend)
this.xstart = xstart;
          this.ystart = ystart;
          this.xend = xend;
          this.yend = yend;
     public Lines(double x, double y)
          this.x = x;
          this.y = y;
               public void distance(final Lines start, final Lines end)
                    delta = abs(Math.sqrt (super.x - start.x) * (super.x - end.x) +
                    (super.y - start.y) * (super.y - end.y));
               Lines move(Point start, double delta)
                    end.x += delta;
                    end.y += delta;
                    return new Point(end);
public Lines show()
g.drawLine( start.x, start.y, end.x, end.y);
public String toString()
return super.toString()+ "\n moved distance is("
               + start + ") : (" + end + ")"
               +" \n to position(" + start + " ) : (" + end + ")";
package Shapes;
public class Rectangle extends Lines
     double delta;
public Rectangle (Point top_lft_pt, Point bottom_rght_pt)
super(top_lft_pt, bottom_rght_pt);
public Rectangle(double x_top_lft, double y_top_lft, double x_bottom_rght, double y_bottom_rght)
super(x_top_lft, y_top_lft, x_bottom_rght, y_bottom_rght);
     public Rectantgle is_it_diagonal()
          if(top_lft.x > bottom_rght.x && bottom_rght.x < top_lft.x)
               System.out.println("Point are Not Diagonal");
               public void distance(double delta)
                    delta = abs(Math.sqrt (top_lft.x - bottom_rght.x) * (top_lft.x - botton_rght.x) +
                    (top_lft.y - bottom_rght.y) * (top_lft.y - bottom_rght.y));
               public Rectangle move(final Point top_lft_pt, double delta)
                    bottom_rght.x += delta;
                    bottom_rght.y += delta;
                    return new Point(bottom_rght_pt);
               public void get_top_rght_coords()
                    Point top_rght = new Point();
                    top_rght.x = bottom_rght.x;
                    top_rght.y = top_lft.y;
               public void get_bottom_left_coords()
                    Point bottom_lft = new Point();
                    bottom_lft.x = top_lft.x;
                    bottom_lft.y = bottom_rght.y;
     public Rectangle show()
                    g.drawLine(top_lft.x, top_lft.y, top_rght_x, top_rght_y);
                    g.drawLine(bottom_lft.x, bottom_lft.y, bottom_rght.x, bottom_rght.y);
                    g.drawLine(top_lft.x, top_lft.y, bottom_lft.x, bottom_lft.y);
                    g.drawLine(top_rght.x, top_rght.y, bottom_rght.x, bottom_rght.y);
package Shapes;
public class Circles extends Lines
protected double radius;
     public double delta;
     protected Point center;
public Circles(double x, double y, double radians)
super(x, y);
          radius = radians;
     public Circles(Point acenter)
          center.x = acenter.x;
          center.y = acenter.y;
public void distance()
delta = abs(Math.sqrt(super.x - x) * (super.x - x) + (super.y - y) * (super.y -y));
     public Circles move(final Point Circles, double delta)
          return new Point(Circles);
public void show()
g.drawOval(Circles.x, Circles.y, radius, radius);
package Shapes;
import java .math .*;
import java.util .Random ;
public class ShapesDriver
Shapes[] aShape = new Shapes[10];
static double range = 101.0;
static Random r1 = new Random();
public static void main(String [] args)
double[][] coords = new double[10][10];
double[] radians = new double [10];
Shapes anyShape = {
new Circles(radians),
new Lines(coords),
new Rectangle(coords)
Shapes aShape; /***error at this line***/
          for(int i = 1; i <= coords.length; i++)
for(int j = 1; j <= coords.length; j++)
                                                  coords[i][j] = r1.nextDouble () * range;
                                                  radians[j] = r1.nextDouble () * range;
aShape[i] = anyShape[r1.nextInt(aShape.length)];
System.exit(1);

Thanks for your help with this problem. Now I have another problem that I am having a hard time figuring out. My program is using inheritance and polymorphism. I trying to use only one version of methods in the superclass points which extends the shapes class which is the abstract superclass vs. repeating the implementation of the methods (move, show, etc.) in each of the subclasses. The error I am getting is this "declare the class abstract, or implement abstract member 'Point Shapes.move()'. As you see, move is declared abstract and of type point in the Shapes superclass and it's behavior is implemented in the subclass Points extending Shapes. The other subclasses, circle, rectangle and lines will invoke the move method from Points and return a new point object. Why I am I getting the error to declare or implement move when the implementation is in Point?
Below is code, please help?
import java .awt .Point ;
public class ShapesDriver
     public static void main(String args[])
          int count = 0;
          int choice;
          Point start = null;
          Point end = null;
          System.out .println(" 1 i am here");
          start = new Point((int)(Math.random()* 10.0), (int)(Math.random()* 10.0));
          end = new Point((int)(Math.random()* 10.0), (int)(Math.random()* 10.0));
     System.out .println(" 2 i am here");
     System.out.println (start);
     System.out.println(end);
     for(int i = 0; i <= count; i++)
          System.out .println(" 3 i am here");
          choice = (int)(4.0 * Math.random());
          System.out .println(" 4 i am here");
          System.out.println (choice);
     switch(choice)
          case 0: //Lines
          System.out .println(" 5 i am here");
          Lines apoint = new Lines((int)(Math.random()* 10.0), (int)(Math.random()* 10.0),
                              (int)(Math.random()* 10.0), (int)(Math.random()* 10.0));
          Point coords = new Point((int)(Math.random()* 10.0),
                         (int)(Math.random()* 10.0));
          new Point((int)(Math.random()* 10.0),
                         (int)(Math.random()* 10.0));
          break;
          case 1: //Circles
          System.out .println(" 6 i am here");
          Circles center = new Circles((double)(Math.random()* 10.0),
          (double)(Math.random()* 10.0), (double)(Math.random()* 10.0),
          (double)(Math.random()* 10.0),(double)(Math.random()* 10.0));
          Circles centerpt = new Circles((int)(Math.random()* 10.0),
          (int)(Math.random()* 10.0), (int)(Math.random()* 10.0),
          (int)(Math.random()* 10.0), (double)(Math.random()* 10.0));
     break;
          case 2: //Rectangles
     System.out .println(" 7 i am here");
          Rectangle top_lft_pt = new Rectangle ((double)(Math.random()* 10.0),
                         (double)(Math.random()* 10.0), (double)(Math.random()* 10.0),
                         (double)(Math.random()* 10.0), (double)(Math.random()* 10.0),
                         (double)(Math.random()* 10.0));
          Rectangle bottom_rgt_pt = new Rectangle ((double)(Math.random()* 10.0),
               (double)(Math.random()* 10.0), (int)(Math.random()* 10.0),
                         (int)(Math.random()* 10.0), (int)(Math.random()* 10.0),
                         (int)(Math.random()* 10.0));
     break;
     default:
     System.out .println(" 9 i am here");
     System.out.println("\nInvalid shape choice =" + choice);
     System.exit(0);
     break;
     try
               System.in.read();
               catch(java.io.IOException ioe)
import java .awt .Point ;
public abstract class Shapes
     private String shape;
     public Shapes(String ashape)
          shape = new String(ashape);
     public abstract Point move();
     public double distance()
          return 0.0;
     public abstract void show();
     public String toString()
          return "\nThis shape is a" + shape;
import java .awt .Point ;
public class Rectangle extends Points
     protected Point top_lft;
     protected Point top_rgt;
     protected Point bottom_lft;
     protected double top_lft_x;
     protected double top_lft_y;
     protected double bottom_rgt_x;
     protected double bottom_rgt_y;
     protected Point bottom_rgt;
     protected double delta = 0;
     protected String shape = "Rectangle";
     public Rectangle(double x, double y, double top_lft_x,
                         double top_lft_y, double bottom_rgt_x,
                         double bottom_rgt_y)
          super(x, y);
          top_lft_x = top_lft_x;
          top_lft_y = top_lft_y;
          bottom_rgt_x = bottom_rgt_x;
          bottom_rgt_y = bottom_rgt_y;
     public Rectangle( double x, double y, Point bottom_rgt, Point top_lft)
          super(x, y);
          bottom_rgt_x = bottom_rgt.x;
          bottom_rgt_y = bottom_rgt.y;
          top_lft_x = top_lft.x;
          top_lft_y = top_lft.y;
     public String toString()
          return super.toString() + " coordinates top left= " + top_lft_x + "," + top_lft_y + "and bottom right" +
               bottom_rgt_x + "," + bottom_rgt_y + ")";
     public void is_it_diagonal()
          if(top_lft_x < bottom_rgt_x && bottom_rgt_x > top_lft_x)
               System.out.println("Points are Not Diagonal");
          public double distance()
               distance ();
               return delta;
          public Point move(Point top_lft)
               move();
               bottom_rgt_x += delta;
               bottom_rgt_y += delta;
               return top_lft;
          public void get_other_coords()
               top_rgt.x = bottom_rgt.x;
          top_rgt.y = top_lft.y;
               bottom_lft.x = top_lft.x;
               bottom_lft.y = bottom_rgt.y;
          public void show()
               super.show();
               System.out.println("new coords are :");
               System.out .println ("(" + top_lft_x + "," + top_lft_y + ")");
               System.out .println ("top right(" + top_rgt + ")");
               System.out .println ("(" + bottom_rgt_x + "," + bottom_rgt_y + ")");
               System.out .println ("bottom right(" + bottom_rgt + ")");
import java .awt .Point ;
public class Points extends Shapes
     protected double delta = 0.0;
     protected double x;
     protected double y;
     protected String ashape = "Points";
     public Points( double x, double y)
          super("Points");
          x = x;
          y = y;
     public Points( Point start)
          super("Points");
          x = start.x;
          y = start.y;
     public String toString()
          return super.toString() + "References coordinates(" + x + y + ")";
     public double distance(double x1, double y1 )
          return delta =(Math.sqrt(x - x1) * (x - x1) + (y - y1) *
          (y - y1));
     public Point move(Point pts)
          pts.x += delta;
          pts.y += delta;
          return pts;
     public void show()
          System.out.println("This shape is a" + ashape + "(" +
                              "(" + x+ "," + y + ")");
import java .awt .Point ;
public class Lines extends Points
     double delta = 0;
     protected double x;
     protected double y;
     protected String ashape = "Lines";
     public Lines( double x1, double y1, double x, double y)
          super(x1,y1);
          x = x;
          y = y;
     public Lines(Point start, Point end)
          super(start);
          x = end.x;
          y = end.y;
     public String toString(Point end)
          return super.toString() + "line points = (" + x + "," + y +
               "(" + end + ")";
     public double distance()
          distance ();
          return delta;
     public Point move(Point lines)
          move ();
          return lines;
     public void show()
          System.out.println("This shape is a" + ashape + "(" +
                              "(" + x + "," + y + ")");
import java .awt .Point ;
public class Circles extends Points
protected double radius;
protected double xcenter;
protected double ycenter;
protected String ashape = "Circle";
     public Circles( double x, double y, double cx, double cy, double radians)
          super(x, y);
          xcenter = cx;
          ycenter = cy;
          radius = radians;
     public Circles( Point acenter, Point ref, double radians)
          super(ref);
          xcenter = acenter.x;
          ycenter = acenter.y;
          radius = radians;
     public String toString(Point ref)
          return super.toString() + " reference points (" +
               ref + ")" +
               "center coordinates (" + xcenter + "," + ycenter + ")";
          public double distance(Point ref)
               return (Math.sqrt(ref.x - xcenter) * (ref.x - xcenter)
                         + (ref.y - ycenter) *
          (ref.y - ycenter));
          public Point move(Point center)
               move();
               return center;
          public void show()
               System.out.println("This shape is a" + ashape + "(" +
                              "(" + xcenter + "," + ycenter + ")");

Reflection: attributes from the base class

Is there a way to get the attributes from the base class of a derived class via reflection? I only found methods to get the attributes from the derived class.
Example:
class A
int a = 4;
class B extends A
int b = 5;
Object unknown = new B();
Code/Idea to get all attributes from baseclass A using unknown (here: a=4)?

Thank you all for your hints. The mistake I make, was to use the baseclass, and not the derived class for getting the attributes. By using an extra parameter of type class I got all attributes in their context.
   private StringBuffer getDump(Object obj, Class cl)
         dmp.append(cl.getName() + " {\n");
         Field[] attribute = cl.getDeclaredFields();             <--- only the fields of the current class
         for (int j = 0; j < attribute.length; j++)
            attribute[j].setAccessible(true);
            try
               if (attribute[j].getType().isPrimitive() || attribute[j].getType() == String.class)
                  dmp.append(attribute[j].getName() + "=" + attribute[j].get(obj) + "\n");
               else
                  if (((attribute[j].getModifiers() & Modifier.STATIC) != Modifier.STATIC) &&
                      (attribute[j].getType().getName().startsWith("java.lang") == false) &&
                      ((attribute[j].getModifiers() & Modifier.FINAL) != Modifier.FINAL))
                     dmp.append(getDump(attribute[j].get(obj), attribute[j].get(obj).getClass())); <- recursive call
            catch (IllegalAccessException ex)
               ex.printStackTrace();
         dmp.append("}");
      return dmp;
   }

SW6U2 (C++) wrong code with empty base class

Consider this program:
#include <assert.h>
#include <new>
struct Base1
int i;
struct Base2
Base2()
struct Derived : public Base1, public Base2
int main( int, char** )
int buf[2] = { 0x7F7F7F7F, 0x7F7F7F7F };
assert( sizeof( Derived ) == 4 );
new (buf) Derived;
assert( buf[1] == 0x7F7F7F7F ); // <- failure
The second assert fails, because the second (empty) base class Base2 is placed at offset 4 of Derived. But when the custom Base2 constructor runs it makes implicit something like
memset( this, 0, sizeof( Base2) );
sizeof( empty class ) is 1 and the offset of Base2 is 4. Effect is that the constructor writes to memory that is not owned by the whole object.
This can produce some subtile memory errors.
Joerg
p.s. What is the right way to submit and view bugs for this C++ compiler?

The forum posting software eats some C++ code. To get all the code displayed, you must use "code" brackets, and leave a space after each "<" and before each ">".
I assume your two include statements are these:#include < assert.h >
#include < new > and that the rest of the code displayed correctly.
Under those assumptions, I cannot duplicate the bug using the initial release of C++ 5.3, nor with the latest patch. Please be sure the code you post actually shows the problem, and use the "preview" button to see that the code displays correctly.
If you still see the bug with the code you posted, please run this command
CC -V -c foobar.cc
and tell me what output you get. The file foobar.cc does not need to exist.

Base classes with Collection attributes

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